# Is this old Furnace Able to be Serviced?



## biggles (Jan 1, 2008)

Nice unit..........:thumbsup: any chance getting that black cover off that round controller there that is your fan control and hi limit...picture...want to see the inside.maybe a new stat and we'll keep it simple will give you more consistant cyclying..so you don't have to talk to it.....it's 40F in NYC this morning and the model numbers off that black cover .there should be a adjustable slide bar within there set it up to 150F for now if its not there...just saw the first pix its at 95F go to 150F 2 wire stat is easy to change no service guy needed we'll help http://www.bestbuyheatingandaircond...2/merchant.mvc?Screen=CTGY&Category_Code=T-MV


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## Marty S. (Oct 31, 2009)

Old furnaces really need to be inspected and serviced every year. That scorch mark over the burners could be a really bad sign.

Way back in high school I had a car with a big V8 and 4 barrel carb. Driving nice it got 8 mpg and when you got on it the gas gauge would drop before your eyes. Didn't take too long to realize 60 gallons a week burnt up was a car payment on a nearly brand new car,gas was around $1 a gallon then. Bought a nice car, drove the same miles and had an extra $50 a month in my pocket even with the car payment. The same lesson applies to 50-60% AFUE furnaces and 6-8 SEER AC's out there. You're spending the payments on a brand new system in energy usage and getting nothing for it. 

PS... I'm a fix it tech, not a salesman. It's 100% up to you on how to spend YOUR money. Just be wise in making choices.


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## biggles (Jan 1, 2008)

tension on that supply fan belt(has to have one at that age) and a clean filter is a definite items to maintain metal fins on the fan squirrel cage or clean and no dirt build up...little oil in the motor if it takes it..leaking duct work even the return where it comes back if the filter is exposed slipping into that duct cover the opening if the basement isn't heated


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## yuri (Nov 29, 2008)

The black scorch marks indicate heat AND smoke which can contain CO Carbon monoxide ARE spilling into your house. INCREDIBLY dangerous for small children and adults. More so for kids as the concentration is higher in their bloodstream. I would replace the thermostat as those stick when they get old. At 120,000 BTU that is a monster of a unit and unless you have a 3-4000 sq ft house it is WAY oversized. I can heat a 1200 sq ft house in Winnipeg where it drops to -40 with that unit. A new furnace will DEFINITELY pay for itself and there may be rebates from your utility co and levels of government. Get 2 new CO detectors if you plan to keep it. One by your bedroom and the other in the basement.

In your climate and if you want air conditioning a air handler and heat pump may be a VERY efficient setup instead. Google "air to air heat pump" or heat pump for more info. We also have some heat pump guys here to help if you want more info.

http://oee.nrcan.gc.ca/publications/infosource/pub/home/heating-heat-pump/whatis.cfm

http://en.wikipedia.org/wiki/Heat_pump


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## vcheez (Jul 12, 2010)

biggles said:


> Nice unit..........:thumbsup: any chance getting that black cover off that round controller there that is your fan control and hi limit...picture...want to see the inside.maybe a new stat and we'll keep it simple will give you more consistant cyclying..so you don't have to talk to it.....it's 40F in NYC this morning and the model numbers off that black cover .there should be a adjustable slide bar within there set it up to 150F for now if its not there...just saw the first pix its at 95F go to 150F 2 wire stat is easy to change no service guy needed we'll help http://www.bestbuyheatingandaircond...2/merchant.mvc?Screen=CTGY&Category_Code=T-MV


I have attached a photo of inside of the controller. There is one set screw underneath that just needed to be loosened. See the attached photo. I didnt want to fool with that slider since I did not know what it was for. What will raising it to 150F do and what is that purpose of the slider. There was no model number on the controller but it did read type # L401A3X5. Thx, VC
*
Inside of Controller*









*Schematic*


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## vcheez (Jul 12, 2010)

yuri said:


> The black scorch marks indicate heat AND smoke which can contain CO Carbon monoxide ARE spilling into your house. INCREDIBLY dangerous for small children and adults. More so for kids as the concentration is higher in their bloodstream. I would replace the thermostat as those stick when they get old. At 120,000 BTU that is a monster of a unit and unless you have a 3-4000 sq ft house it is WAY oversized. I can heat a 1200 sq ft house in Winnipeg where it drops to -40 with that unit. A new furnace will DEFINITELY pay for itself and there may be rebates from your utility co and levels of government. Get 2 new CO detectors if you plan to keep it. One by your bedroom and the other in the basement.
> 
> In your climate and if you want air conditioning a air handler and heat pump may be a VERY efficient setup instead. Google "air to air heat pump" or heat pump for more info. We also have some heat pump guys here to help if you want more info.
> 
> ...


Thanks for the info. Does the black marks indicate that CO is spilling into the house for sure? I have CO monitors installed through out the house and have never had them go into alarm. Could the black marks also be the result of this heater being 50+ years old and its just the result of normal firing-up wear and tear?
My house is only 2000 sq ft. I knew this unit was big but I didn't know that it was WAY oversized. I just figured that it was from an era where all American products were built strong and stout. 
I'm planning on getting a new furnace but not now. I just got a new water heater and re-piped the house so I need to save my money for the next job. Also, please note that we only heat the house from November to February so most of the year the temperature is very mild.
The heat pump sounds interesting. I still don't understand it and I don't know if anyone around here has one but I would love to get an estimate. I gotta take a little more time and carefully read the links that you gave. I don't understand where the warm air comes from during the winter.



Marty S. said:


> Way back in high school I had a car with a big V8 and 4 barrel carb. Driving nice it got 8 mpg and when you got on it the gas gauge would drop before your eyes. Didn't take too long to realize 60 gallons a week burnt up was a car payment on a nearly brand new car,gas was around $1 a gallon then. Bought a nice car, drove the same miles and had an extra $50 a month in my pocket even with the car payment. The same lesson applies to 50-60% AFUE furnaces and 6-8 SEER AC's out there. You're spending the payments on a brand new system in energy usage and getting nothing for it.


 I understand the economics of my scenario but I can afford the monthly payment for now. What I cannot afford right now is the $5000 one time payment for installation of the new system. The only exception that I would make is if I was in any immediate danger of CO poisoning. Then I would go to Home Depot and get on the payment plan. I just need to make it until next summer and I should have the extra cash by July. I'm just starting my research early and I love the advice and conversation that arises at the DIY chatroom. You guys collectively really know your stuff. Here are a couple more photos for reference. 
When I get the new unit, I would want to re-use my existing ducts. They seem huge compared to the modern stuff. Based on the pictures below, do you think I can use the same ducts with a new heater. Also please let me know any good brand furnaces that are recommended. I also included a couple more pics of a few areas of the furnace.

*Side View*









*Pilot Light and Thermopile*









*Close Up of Burn Damage*









*The Bottom with the Cover Off*


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## yuri (Nov 29, 2008)

Consumer CO detectors cost $50. The Pro unit the gas co has costs $1000 and can pickup 1 ppm guaranteed 99% or more of the time and is calibrated yearly. My Pro unit is $200-500 and a bit less accurate. Cannot get that reliability and accuracy for $50. See where I am going? The consumer model is designed for catastrophic failures where chimneys collapse, get plugged or large amounts of CO spill. You could be breathing 10-50 ppm for weeks B4 some of them alarm. Some fire depts and agencies recommend you replace them every 5 yrs as they lose their sensitivity. Looks like an old GE unit we had here and I am sure I can find cracks in it. It is GROSSLY oversized. Your ducts are huge and fine and they will build sheetmetal adaptors to fit a new unit in.


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## biggles (Jan 1, 2008)

nice pix ...before i say push the fan temp up how HOT is the air coming out of the rgisters with a hand over them...i'll guess 87F:wink: and hw s the air coming out slightly... forceful...pick a word.you might want to bump that top dial up a bite like to 125F and if your short on air out of the register shut the furnace power OFF:yes:take an allen key sitting in frontor kneeling and reaching in to the sheave/pully on the motor loosen the outer plate and ONE full turn away from were your sitting follow the allen key screw...and end up right back from where you started.. you just sped up the RPMs on the motor....this will bring in the sheave... speed up the motor and give you more air.tighten it down on the flat part of the threaded piece there....if the belt was a little loose this will actually tighten the belt up without adjusting the motor mounts....this is just info but easy to do but get back with quetions if you leary of doing this...but definitly bump that dial up a bit...it will give you hotter air and might solve the fan being on all the time.....with the unit off run your index finger inside th squirrel on the fan fins to see if you have any dirt dropping off them dust is OK but any dirt will cut down on the air being thrown up the duct to heat....do you have a good percentage of wood floors or carpet..pets dogs cats...just wondering always used 1" pleeted filters there.if you want to scent the house up for the hilidays a solid air freshener in the fan section will scent the entire house...thats freeeee


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## biggles (Jan 1, 2008)

wanted to add this on the soot situation seperate from my last ramble....the cycle when the stat calls is the gas valve and the main burner comes up what we need for you to see is with the flames just as the fn comes on if your heat exchanger is tight no cracks :thumbsup: the flame shouldn't waver as if you were blowing on them...if they wave bigtime just as the fan comes on and contiue to wave and swirl...you need to shut it down and have somebody in to do a test on it....Southern Cal gas might have a program for changing out a furnace thru them and their contractors and paying it off thru a monthly blling so you won't take a hit...exhaust that option and ask around about heating contractors...watch yourself.....and if you go for a new furnace tell them you want a new digital stat for FREEEEEEEE


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## Marty S. (Oct 31, 2009)

Only a tech on site can check the safety of your furnace. Roll out like that often happens from a big crack in the heat exchanger or soot build up in the exchanger. Sooted up and roll out together is as dangerous as it gets. The pictures sure look like black soot on the center burners and the big tan spot along with burnt off paint is from flame roll out. Don't mess around, get it checked ASAP!


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## how (Feb 26, 2011)

To test for a possible exchanger crack and a possible safety concern for spillage being the reason the paint is falling off.

Turn up the thermostat, lay down on the floor and watch the flame from the burners, don't breath towards the burners or disturb the dust in the area. Wait until the blower comes on to see if the flames change with the
start up of the blower. Do this for 10 minutes because some cracks only open up after the exchanger fully heats up. Make sure that a heating outlet is not blowing directly towards the burner area which will mess up your results.

Do this test again but this time turn down the flames on the burners as low as you can without them going off. This is done with a carefull partial tuning down of the main gas cock to the right of your gas valve. This makes the flames very soft and more suseptable to the air disturbances that a cracked exchanger can cause. Once again you are watching for the flames to wave around when the fan starts.

Return the gas cock to the normally "on" position, close up all the windows and doors in your house, turn on your clothes dryer and use the smoke of an incense stick to make sure that the products of combustion are not coming out by the burners where the paint is now coming off. The smoke from the incense should be drawn into the furnace when the incense is brought in close between the inside and outside of the furnace just a 1/2 inch above the burners.

Let us know what you find.

Ps My other concern is that your present motor is dangerously ungrounded but it's easy to fix that by attaching a ground from the motor it to the furnace body.


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## vcheez (Jul 12, 2010)

yuri said:


> Consumer CO detectors cost $50. The Pro unit the gas co has costs $1000 and can pickup 1 ppm guaranteed 99% or more of the time and is calibrated yearly. My Pro unit is $200-500 and a bit less accurate. Cannot get that reliability and accuracy for $50. See where I am going? The consumer model is designed for catastrophic failures where chimneys collapse, get plugged or large amounts of CO spill. You could be breathing 10-50 ppm for weeks B4 some of them alarm. Some fire depts and agencies recommend you replace them every 5 yrs as they lose their sensitivity. Looks like an old GE unit we had here and I am sure I can find cracks in it. It is GROSSLY oversized. Your ducts are huge and fine and they will build sheetmetal adaptors to fit a new unit in.


Thanks Yuri. I actually work in the gas detection business so I think I will order a commercial monitor from one of my suppliers. I mainly work with highly toxics and flammables but I think I will get a personal sniffer and I'll verify it's calibration with 50ppm gas standard. I appreciate and respect the advice that I get from you guys. I have to admit that this furnace has always made me a little nervous but I have felt safe with all of the CO monitors all over the place. I also keep a window slightly cracked.


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## vcheez (Jul 12, 2010)

Marty S. said:


> Only a tech on site can check the safety of your furnace. Roll out like that often happens from a big crack in the heat exchanger or soot build up in the exchanger. Sooted up and roll out together is as dangerous as it gets. The pictures sure look like black soot on the center burners and the big tan spot along with burnt off paint is from flame roll out. Don't mess around, get it checked ASAP!


I gotta find an honest tech who can will show me if the exchanger is cracked. Please tell me what is dangerous about soot and roll out. If the exchanger is not cracked and soot and roll out are the problem, can the soot just be cleaned out? 
Where is the heat exchanger anyways? Is it visible from my photos? Thank in advance, VC


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## how (Feb 26, 2011)

It is understandable that joselling the thermostat wires near this thermostat could cause problems because this thermostat/gas valve system operates on just 1/2 a volt which needs excellent contacts to work properly. What I don't get is purpose of the double mercury bulbs in the fan controller. I am assuming that this contoller has a spiral bymetal contol within the exchanger that turns as it heats or cools. The schematics seem more suited to an old oil furnace than a gas furnace. I wonder if the fan controls have been adjusted to a 24/ 7 operation because they were working so badly.??????


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## vcheez (Jul 12, 2010)

how said:


> To test for a possible exchanger crack and a possible safety concern for spillage being the reason the paint is falling off.
> 
> Turn up the thermostat, lay down on the floor and watch the flame from the burners, don't breath towards the burners or disturb the dust in the area. Wait until the blower comes on to see if the flames change with the
> start up of the blower. Do this for 10 minutes because some cracks only open up after the exchanger fully heats up. Make sure that a heating outlet is not blowing directly towards the burner area which will mess up your results.
> ...


I tried your testing and did not notice a difference in the flame when I turned on and off the blower but I'm not qualified to determine if what I was observing means that the heat exchanger is cracked or not. I didn't try the low gas test but I may give that one a try tomorrow. I need some one to help me because by the time I adjust the thermostat and run to the basement, it already starts up. It's just me and the wife at home now that the kids are off at college so I don't have as much help around the house for things like this.
You are right about the motor not being grounded. I have replaced about half of the 2/3 of the knob and tube wiring in my house but the receptacle that feeds the furnace does not have a ground. The gas pipe however is bonded to my water pipes which are bonded to my electrical panel and an 8' copper ground rod.


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## vcheez (Jul 12, 2010)

biggles said:


> nice pix ...before i say push the fan temp up how HOT is the air coming out of the rgisters with a hand over them...i'll guess 87F:wink: and hw s the air coming out slightly... forceful...pick a word.you might want to bump that top dial up a bite like to 125F and if your short on air out of the register shut the furnace power OFF:yes:take an allen key sitting in frontor kneeling and reaching in to the sheave/pully on the motor loosen the outer plate and ONE full turn away from were your sitting follow the allen key screw...and end up right back from where you started.. you just sped up the RPMs on the motor....this will bring in the sheave... speed up the motor and give you more air.tighten it down on the flat part of the threaded piece there....if the belt was a little loose this will actually tighten the belt up without adjusting the motor mounts....this is just info but easy to do but get back with quetions if you leary of doing this...but definitly bump that dial up a bit...it will give you hotter air and might solve the fan being on all the time.....with the unit off run your index finger inside th squirrel on the fan fins to see if you have any dirt dropping off them dust is OK but any dirt will cut down on the air being thrown up the duct to heat....do you have a good percentage of wood floors or carpet..pets dogs cats...just wondering always used 1" pleeted filters there.if you want to scent the house up for the hilidays a solid air freshener in the fan section will scent the entire house...thats freeeee


The air is warm when it comes out of thr registers. It feels nice. The dog likes it too. Sometimes, when the heat comes on, he runs over and sits in front of the register. I guess it wont hurt to try cranking up that dial to see if anything changes. How does changing that dial make for a hotter flame? Please explain.


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## yuri (Nov 29, 2008)

Soot is a sign of incomplete and bad combustion. Nat gas needs a precise air to gas mixture and draft to burn a nice clean blue flame. Soot is caused by a lack of oxygen AND or not enough draft thru the exchanger because the passages are blocked by soot. Proper combustion of gas gives you CO2 and water vapor and a small amount of sulphur. Lack of oxygen deletes one O molecule so you get CO instead of CO2. It is almost impossible to completely or properly clean a heat exchanger w/o physically removing it and taking it to the car wash and using high pressure water. Google natural draft gas burner for more info on how to burn gas properly. Or borrow the Fundamentals of Gas Utilization from the library. Rollout means exactly what it says.


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## vcheez (Jul 12, 2010)

yuri said:


> Soot is a sign of incomplete and bad combustion. Nat gas needs a precise air to gas mixture and draft to burn a nice clean blue flame. Soot is caused by a lack of oxygen AND or not enough draft thru the exchanger because the passages are blocked by soot. Proper combustion of gas gives you CO2 and water vapor and a small amount of sulphur. Lack of oxygen deletes one O molecule so you get CO instead of CO2. It is almost impossible to completely or properly clean a heat exchanger w/o physically removing it and taking it to the car wash and using high pressure water. Google natural draft gas burner for more info on how to burn gas properly. Or borrow the Fundamentals of Gas Utilization from the library. Rollout means exactly what it says.


Thanks for the info. :thumbsup: I appreciate your concern and sound advice. I just ordered a commercial CO monitor and it should be delivered to my shop by Wednesday. I'll test measure the concentration of CO at all locations and post the results for any other forum members who maybe concerned or are in a similar situation. In addition, I also order a 50ppm balanced with air calibration gas mixture so I will not test my existing $50 Home Depot CO monitor vs. my new $500 electrochemical commercial monitor and see if they both respond upon exposure to 50PPM CO. 50PPM is the Permissible Exposure Limit (PEL) of CO and 1200PPM is the immediately dangerous to life and health (IDLH) concentration for CO. Hopefully, the concentration that I measure will be less than both.


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## yuri (Nov 29, 2008)

maximum permissible concentrations per hour of CO for humans and the cumulative effects.

http://www.carbon-monoxide-poisoning.com/article1-co-levels.html

http://www.epa.gov/iaq/co.html

http://www.osha.gov/SLTC/healthguidelines/carbonmonoxide/recognition.html


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## vcheez (Jul 12, 2010)

yuri said:


> maximum permissible concentrations per hour of CO for humans and the cumulative effects.
> 
> http://www.carbon-monoxide-poisoning.com/article1-co-levels.html
> 
> ...


Thanks for the additional information on carbon monoxide exposure limits and the cumulative effects. I usually use the OSHA PEL of 50 PPM as my alarm limit but if I'm even close to measuring that concentration in my home, then there is a serious problem that will need to be addressed immediately. I can hardly wait for my new monitor to arrive so that I can measure the concentrations with an accurately calibrated instrument.


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## yuri (Nov 29, 2008)

check it randomly near the furnace several times a week during one or two months( with it fired up obviously). You may lose the draft in your chimney or have a weaker draft on non windy days so checking it several times to get a good representative sample is required.


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## joepierson (Oct 26, 2011)

200 years from now they are going to think we were nuts installing these potentially deadly heating contraptions in our houses


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## biggles (Jan 1, 2008)

adjusting the discharge air temp...as you make it higher on the setting the mercury bulb is on a metal pigtail sticking into the furnace between the chambers...as it heats up the metal expands and you get a higher temp.if your happy with that at 87F range leave it....later models run 150F and the fan comes on...i was just seeing about that fan running all the time..that soot on the front is from the heat Exchanger maybe carbonized with soot... have somebody brush up into it...during a maint.visit.the heating cycle on a unit that old is STAT calls .."standing pilot" main burner comes on....heat exchanger heats up and that controller reacts to the heat turns the fan on.....place heats up...stat satisfies...main gas off...fan removes balance of heat into the space heate exchanger cools off and the controller reacts below setting and fan goes off till next cycle...


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## vcheez (Jul 12, 2010)

joepierson said:


> 200 years from now they are going to think we were nuts installing these potentially deadly heating contraptions in our houses


Yes for sure. It's like those old Victorian Homes that have gas wall lamps. Those things freak me out.


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## harleyrider (Feb 20, 2007)

i first off want to admit that i did not read every post post in this thread, but the simple answer to the posters question is yes of course any furnace can be repaired. In this case it is not advisable, due the the obvious signs of flame roll out in the burner area,this is a sure sign of a much more serious and potentially deadly condition that exist. Replace this unit, do not repair and also take it out of service right away.


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## vcheez (Jul 12, 2010)

biggles said:


> adjusting the discharge air temp...as you make it higher on the setting the mercury bulb is on a metal pigtail sticking into the furnace between the chambers...as it heats up the metal expands and you get a higher temp.if your happy with that at 87F range leave it....later models run 150F and the fan comes on...i was just seeing about that fan running all the time..that soot on the front is from the heat Exchanger maybe carbonized with soot... have somebody brush up into it...during a maint.visit.the heating cycle on a unit that old is STAT calls .."standing pilot" main burner comes on....heat exchanger heats up and that controller reacts to the heat turns the fan on.....place heats up...stat satisfies...main gas off...fan removes balance of heat into the space heate exchanger cools off and the controller reacts below setting and fan goes off till next cycle...


Thanks for the reply biggles but I'm new to furnace work and your slang and incomplete sentences is very difficult for me to follow. I do appreciate you taking the time to write me back and the info you presented sounds useful if I could decipher your "lingo". 
I just really want know why my fan runs 24 x 7 whether the not the burner is on or off. It sounds like it might have something to do with that dial. Are you saying that if I raise the setting from 87 to 150, my fan will have the ability to turn off sometimes? 
I'll probably wait for my CO monitor to arrive before making any adjustments but I'm still trying to understand why the fan is always running.
If anyone knows a good old timer HVAC man in the South SF Bay Area who can help me out, I'm all ears. Thx, VC


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## vcheez (Jul 12, 2010)

harleyrider said:


> i first off want to admit that i did not read every post post in this thread, but the simple answer to the posters question is yes of course any furnace can be repaired. In this case it is not advisable, due the the obvious signs of flame roll out in the burner area,this is a sure sign of a much more serious and potentially deadly condition that exist. Replace this unit, do not repair and also take it out of service right away.


Thanks for the advice. Since you have not read the threads, I will fill you in on what's going on. 
I have ordered a commercial grade CO monitor that is due for delivery tomorrow. The results of my tests and the measured CO concentration will determine whether or not I take this heater out of service or not. If I don't measure, CO flowing into my home, is there still any other reason to take this furnace out of service?
Everyone keeps mentioning flame roll out. I watch the unit when it starts up and when it burns and I don't see any flames rolling out. There might be a little flash when the flames ignite but its not like the fire is burning outside of the furnace. 
Does flame roll out mean that flame are burning outside of the chamber?

Thx, VC


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## yuri (Nov 29, 2008)

The fumes are spilling out the front of the furnace and you cannot see or smell them. At that age the heat ex can be partially plugged with normal rust and has some soot from bad combustion. You may also have a draft problem with your chimney and not enough draft thru the furnace caused by the plugging up heat exchanger. Visual signs like that are HUGE red flags and it depends on the homeowner whether he wants to see them or not. Natural gas natural draft furnaces like yours are not on/off logical devices where they can be considered safe or not. Experienced Pros have seen that those units and have done CO poisoning calls and know what units generate those calls.

A properly burning and drafting furnace can go 30-40 yrs where I am and have NO sign of spilling or charring.


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## Marty S. (Oct 31, 2009)

There's also a 200ppm limit of CO in the flue gas even if it's not dumping into the house. Soot in the exchanger results in CO levels many times that. Perhaps your new meter can test that too. It might ruin it in seconds though so read the directions.

The reason most have not got into the fan issue is we,as techs in the field, make sure the furnace is safe before moving on to any other issues. The same concern is carried over with our advice on this forum. Step one is ALWAYS peoples safety.


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## how (Feb 26, 2011)

Flame spillage can easily be tested out with a source of smoke just an inch above the burners on the line between the inside and the outside of the furnace. A cigarette will do it. When the burners initially light you will get an ignition that might push some excess fumes out of the burner opening area but only for a second or two. This will discolor the area outside of an older furnace above the burners over time. After that, the air in the room should reverse and be flowing into the burner chamber, through the furnace and up the chimney. If you hold a something that produces consistant smoke (cigarette or incense) right at the opening above the burners you will see if spillage (What you don't want) is pushing the smoke away from that opening or if the correct direction of air (smoke)is being pulled into the burner chamber. You can even hold a lit lighter just above the burners and beside the furnace body and if you have spillage, it will put out the lighter flame. Eventually just holding your hand along there will tell you if there is a problem or not. Spillage will produce moist hot air out of the burner chamber whereas a correct direction of air will not.

If it passes your test, do it all again with all the house windows & doors closed and the clothes dryer on. This will create a low pressure area within the house that will most likely produce spillage if your house has insufficient fresh air coming in to counter it.
If it passes this test then, then your unit is not spilling.

Let us know what the result is. This test only indicates spillage and not a cracked exchanger.


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## vcheez (Jul 12, 2010)

yuri said:


> Visual signs like that are HUGE red flags and it depends on the homeowner whether he wants to see them or not.


I will admit that I don't think that CO is spilling out of the furnace based on the fact that I have so many CO monitors all around my home and even in the last couple of days since talking with you guys I installed 2 more in the basement right on the furnace. See the new photos below for reference.
I bought 10 of these little detectors from a local fire alarm device distributor awhile back. I put seven in the house and had 3 left over so I just mounted these around the furnace and I have not even got a "blip" of CO detection. I do of course remember what you said a few days ago about these $50 dollar units not being too good at detecting low levels.

It doesn't take an expert to know that an old furnace like this could be very dangerous. It is probably the most potentially dangerous part of this old house that I live in.

I do however completely respect the opinions of the experts here at the forum that is why I've decided to buy the commercial unit and the 50PPM calibration gas that will be delivered tomorrow I hope. 
Besides colorless, odorless, toxic gases have no friends and if there is a serious problem, I'm not going to be the fool :jester: who ignored the advice of experts because I didn't want to see the red flags.



Marty S. said:


> There's also a 200ppm limit of CO in the flue gas even if it's not dumping into the house. Soot in the exchanger results in CO levels many times that. Perhaps your new meter can test that too. It might ruin it in seconds though so read the directions.
> 
> The reason most have not got into the fan issue is we,as techs in the field, make sure the furnace is safe before moving on to any other issues. The same concern is carried over with our advice on this forum. Step one is ALWAYS peoples safety.


Thanks Marty. The monitor that I've purchased has a range from 0-500PPM so It can handle a 200PPM hit with no problem. I could run into trouble if It was exposed to a super high concentration of something like 10,000PPM for a long period. If that were to happen, I could purchase a new cell for around $150 I think. I guess I'll have to climb up on the roof and measure the output of the stack. I hate climbing up on that tile roof because its hard to walk on and I don't want to break a tile with the rains coming this weekend. Thanks guys, VC

*CO Monitor Mounted Above the Furnace*









*Close Up of the CO Monitor*









*CO Monitor on the Side Between the Furnace and Exhaust Chimney*


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## danpik (Sep 11, 2011)

I have been following this thread for a bit now and noticed something today. The pilot light on this furnace is not controlled by the thermocouple. The thermocouple only controlls the main burner. Should the pilot light go out for any reason the gas valve will not turn of the flow of gas to it. 
As to can this unit be upgraded...Yes, provided that the heat exchanger is in good shape. A "modern" gas valve and fan control could be retrofitted to this unit very easily. I did one similar about two years ago for a guy who did not want to spend the money on a newer furnace. The fan staying on all the time is most likely due to the fan limit switch either being out of adjustment on the low side or the contacts stuck closed. I have only seen one fan relay like that ever and it was on a unit that we took out of a house so I do not know where the adjustment points are on it or even if the low limit is adjustable.
One other concern is the wrap/coating on the duct work. It is entirely posible that it is some form of asbestos. Before you disturb anything I would at least get a sample tested. In its current state It poses no harm, in fact, it looks like someone painted it which would lock in any loose fibres from escaping. I don't mean to panic you with this but to inform you so you are aware.


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## how (Feb 26, 2011)

I'm not sure I'd worry about the pilot gas leaking into the furnace after the thermocouple has shut down a furnace. Too small an amount of gas to accumulate and will just waft up the chimney. A pretty standard design for a furnace of this vintage. 
30 seconds of unignited main valve gas failure will destroy a furnace if it finds a sourse of ignition, but that's another story.
You are also right about the probable asbestas wrap. You can see pieces of it in the photo where the vent has been scraped to metal.
Also pretty common, as is the paint covering for this age of unit.


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## yuri (Nov 29, 2008)

It is an old millivolt system with a "standing pilot" not enough gas from the pilot to cause an explosion. Even a modern system with a thermocouple will still pass gas for up to 2 minutes until it cools down and drops out the gas valve. They engineer them so it can pass safely up the chimney with the natural draft and if it ever lights up will blow out the front harmlessly as long as NO combustibles are stored with 2 feet of the front. Causes some laundry stains in the ole shorts but is UL and AGA/CGA tested for a flameout scenario.

Some installers will refuse and have the right to refuse to work on units unless the asbestos is PERFECTLY sealed/encapsulated by paint or removed. Workplace Health and Safety rules etc. Can't say I blame them as once you start shaking the old furnace and banging the ductwork any unsealed fibers can start floating around. Not good for the homeowner either.


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## vcheez (Jul 12, 2010)

danpik said:


> One other concern is the wrap/coating on the duct work. It is entirely posible that it is some form of asbestos. Before you disturb anything I would at least get a sample tested. In its current state It poses no harm, in fact, it looks like someone painted it which would lock in any loose fibers from escaping. I don't mean to panic you with this but to inform you so you are aware.


As far as I know it is 100% asbestos. I had my wife paint it when we moved in to keep the fibers intact. She is a damn good painter. I told her that when I get the new heater, the workers may want to replace the ducts with new non-asbestos wrapped ducts and she said, "Why in the hell did you make me paint them then.":furious:
There are many things in this old house that are not safe by modern standards and I'm taking care of them one by one until they are all up to current codes and standards. The paint was added just to buy some time until we install a new furnace. If I can find a contractor who is careful and not afraid of little asbestos, then I will try to use the existing ducts and tell them to be careful cutting away some of the asbestos where the sheet metal will transition from the furnace.


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## vcheez (Jul 12, 2010)

how said:


> Flame spillage can easily be tested out with a source of smoke just an inch above the burners on the line between the inside and the outside of the furnace. A cigarette will do it. When the burners initially light you will get an ignition that might push some excess fumes out of the burner opening area but only for a second or two. This will discolor the area outside of an older furnace above the burners over time. After that, the air in the room should reverse and be flowing into the burner chamber, through the furnace and up the chimney. If you hold a something that produces consistant smoke (cigarette or incense) right at the opening above the burners you will see if spillage (What you don't want) is pushing the smoke away from that opening or if the correct direction of air (smoke)is being pulled into the burner chamber. You can even hold a lit lighter just above the burners and beside the furnace body and if you have spillage, it will put out the lighter flame. Eventually just holding your hand along there will tell you if there is a problem or not. Spillage will produce moist hot air out of the burner chamber whereas a correct direction of air will not.
> 
> If it passes your test, do it all again with all the house windows & doors closed and the clothes dryer on. This will create a low pressure area within the house that will most likely produce spillage if your house has insufficient fresh air coming in to counter it.
> If it passes this test then, then your unit is not spilling.
> ...


Thanks How. You described exactly what I think is happening. I noticed when the burner first starts, a flame comes out of the front for just a second or so. The main section that had fire coming out was that one burner tube that has the most black soot on it. (Second from the left) That was the only spot that for a second or so had an orange flame come out of the furnace for about 2-3". I guess that it why there is a main door that should kept on the front and your not supposed to install combustibles nearby. Shortly after that, when the burner fully ignites, there is no flame outside of the chamber and its mainly a blue flame on the inside. I think that over the 50 or so that years this furnace has been in service and all the times the burner has turned on has caused the damage. 

I tried the smoke test without the dryer off and then with the dryer on and in both cases, the smoke was drawn into the furnace. That test was simple and nice and I feel a little bit safer after observing the results.

My fancy CO monitor did not arrive today. I gotta wait one more day. I also ordered a flammable vapor detector. I just figured that it would be nice to measure CO and any non-burned natural gas too. 
Well, as per your request, I posted the results of the smoke test. Now what should do? Do you think I could just blow some compressed air up that tube with the soot on it? Maybe it just needs a little cleaning. Thanks in advance, VC

*Burner Tube With Most Soot is Where 1-2 Sec Flame Out Occurred*


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## how (Feb 26, 2011)

A picture directly facing the burners will tell me more but it doesn't look like you have much room to maneuver. Most furnaces of your vintage have more room at the burner opening to inspect and do some long brush work up into the exchanger to remove the soot. If one burner seems to be the problem then the gas/air opening at the front of that burner might have been set up too small. Open it right up to see if you have a dust/debris build up inside the mouth of that burner. Adjust the gas/ air shutter for a bit wider of an opening and fire up the furnace. See if the flames from the problem burner seem to float lower in the burner chamber than the other burner flames.

If they do float lower compared to the other burners then some exchanger cleaning is in order. If you do decide to blow compressed air up into the exchanger then that soot will blast out the opening in the back of this furnace where the chimney vent meets the furnace.
I have been told of people who seal off this opening for the exchanger blow out and send most of the soot up the chimney. There the soot just covers the roof around the chimney for all to see. A poor practice for many reasons.
Another way to gain access for exchanger cleaning is to remove the vent pipe at the back of the furnace to clean downwards with brushes, chains or compressed air and with a vaccum running on top of that burners to collect most of the soot. If you do have soot in the exchanger you are in for a messy job.


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## yuri (Nov 29, 2008)

If you decide to try clean that unit it should be a COMPLETE proper cleaning procedure or none at all. Once you start blasting air in there the soot and rust will mostly fall back down and onto the burners. You can hire a duct cleaner with a huge vacuum and then spray compressed air in with a flexible hose. When I do a job like that I remove the burners and draft diverter/hood that the vent pioe attaches too. Then the baffles inside the exchanger need to be removed if possible. At that age they could break and crumble from rusting. Damage them and you won't get proper draft thru the exchanger and bad combustion. Once again if you mess with it and cause rust to fall inside the exchanger it may make matters worse and mess up the draft which changes the gas/air mixture and combustion. Gas burning 101.


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## how (Feb 26, 2011)

See if you can arrange a mirror and light to inspect the exchanger area above that burner. Its proximety to the pilot means that you may be only needing to deal with light fluffy white precipitate that is sticking to the upper sides of that part of the heat exchanger. It's whiteness makes it easy to see in there whereas sooting makes it almost impossible. A precipiate build up is enough to cause the burner flame to float. Long bent soft brushes will dislodge that and a running vaccum hose inside that burner will suck up what you dislodge. Another 4" brush into the top end of the exchanger from the vent hood area is the next step if your lower brushing doesn't stop the floating flames.


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## vcheez (Jul 12, 2010)

Thanks guys for the tips on cleaning. That sounds like a really nasty dirty job and I don't think that will be my "cup of tea". I think I would like to hire an experienced person to take care of the cleaning if it involves more than blowing air, vacuuming or brushing.

I do have good news. My commercial monitors arrived today and all is good everywhere I measured for CO and combustible vapors. :thumbup:
I have measured every register in the house, and all areas around the furnace and detected absolutely no CO. I witnessed a factory calibration of the unit today so I know its reading accurately. This furnace might be old and inefficient but is not leaking CO into my home or basement. I checked an 8 hour TWA (time weighted average) of CO exposure at my bedroom register and max CO reading and the values were 0 PPM.

Now that I have established that I am not in immediate danger from CO poisoning, can some one perhaps shed some light on why my furnace fan runs 24 x7 or at least explain how that dial controller works. In the summer, its kind of nice having the fan run all the time because it acts as a poor man's AC as it brings up cool air from the basement. In the winter, it appears to make the heater work more than it needs to because right after the heater warms the house it starts bringing in cool air which drops the temp faster than it would if there was no fan on. 
As suggested by one of the other helpful members of the forum, I just spun the controller dial up to 150 and my fan tuned off for the first time. I ran upstairs, raised my thermostat to 72 and then ran back to basement and heard the burner turn on. It ran for about two minutes then the fan started-up. I then ran upstairs dropped the thermostat to 68 and then the burner turned off but the fan continued running for about 3 minutes and then it finally turned off again. It seems that raising the dial up to 150 is making the furnace run properly. Are there any problems with raising the set-point up to 150?

*Controller With Temp Raised Setting Raised to 150*








If anyone knows how old this this furnace is, I would love to know. I think its from 1942 based on the serial number and the logo, "The Clipper Seaplane" was in service during the 1940's.
I'm beginning to do my research on replacing this furnace, but since I know its not dumping CO into my home, the urgency to replace it has decreased a bit. Thanks in advance, VC


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## how (Feb 26, 2011)

When you move the arm on top of the combination fan control towards the left, does the top glass mercury switch also tilt to the left?
I am wondering if the mercury switch tilts below the horizon to the left, if the fan will shut off?
Be gentle with it!


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## vcheez (Jul 12, 2010)

how said:


> When you move the arm on top of the combination fan control towards the left, does the top glass mercury switch also tilt to the left?
> I am wondering if the mercury switch tilts below the horizon to the left, if the fan will shut off?
> Be gentle with it!


The switch was already on the left all of the time and when it was in that position, the fan would not turn off. It makes me a little nervous to mess with these controls especially since I have no instruction manual stating what are the normal settings.


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## how (Feb 26, 2011)

OK, a few choices to check out a theory. First we need to confirm that the top glass tube can turn the fan off.
Yes playing with an old control may break it but as this control is made to turn the fan on & off, and it doesn't..you don't have much to lose. I am assuming that you've never seen the top glass tilting below the horizen to the left.

Have you tryed moving the lever on top of the control over towards the right hand side to see if that top glass mercury tube will tilt to the left?

If moving the arm above the control doesn't do it, you can either try to manually tilt it over to the left to see if the fan blower stops..or..
you can turn off the furnace power/ unscrew one of the lines connected to the top glass tube where they are screw connected, isolate that loosened end (tape it or bend it away from conductive metal) and then turn the power back on to see if the fan has stopped.

This is just for testing purposes. The power will need to be turn off again and the wire re attached as it was for the furnace fan to heat the house.

Let us know the results.


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## vcheez (Jul 12, 2010)

how said:


> OK, a few choices to check out a theory.
> Yes playing with an old control may break it but as this control is made to turn the fan on & off, and it doesn't..you don't have much to lose.
> 
> Have you tryed moving the lever on top of the control over towards the right hand side to see if that top glass mercury tube will tilt to the left?
> ...


Ok. I'm gonna give it a try tomorrow morning. It's getting late and I'm tired but please note that by moving the lever to 150, the fan is turning on and off now. It turns on about 2 minutes after the burner starts up and it turns off about 2-3 minutes after the burner turns off. I had the cover on when I was changing the lever position so I don't what the mercury was doing since I could not see it. 
I'm not worried about damaging the controller when I move the lever, I'm more concerned about overheating the furnace and causing a dangerous situation since I don't know why there would be a need for the various settings at the furnace. It seems like the variation in temperature should be made from the thermostat. Thx, VC


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## how (Feb 26, 2011)

I hope that the top glass tube turns off the blower fan at the temperture you could once select. This will be confirmed when you watch it's operation with the cover off. It was probably set for 90F when it was new but it now needs to be turned up to 150F to do the same thing because of aging wear. Two minutes is not bad a time delay for the fan to come on but it was probably originally four minutes. The same for when the gas turns off..about a four minute delay. A hand temp test at the registers after the gas valve turns itself off will tell you if the blower is on long enough. If its still hot when the fan shuts off, its costing you in lost heat.

I guess I could of saved me some writing if I asked you why you were not happy with the fan running all the time. You will never have it as efficient, or as evenly distributing the heat as when the fan is running all the time!


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## yuri (Nov 29, 2008)

You can safely set it at 150 deg. I replaced hundreds of those back in the 70s and 80s and would set them at 150. The heat exchanger is literally so thick and heavy that nothing short of a bomb could hurt it. Do the random sampling of CO on different days (cooler, hotter and windy and non-windy) so you get a good representative sample and then you can feel safer.


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## vcheez (Jul 12, 2010)

how said:


> Two minutes is not bad a time delay for the fan to come on but it was probably originally four minutes. The same for when the gas turns off..about a four minute delay. A hand temp test at the registers after the gas valve turns itself off will tell you if the blower is on long enough. If its still hot when the fan shuts off, its costing you in lost heat.
> 
> I guess I could of saved me some writing if I asked you why you were not happy with the fan running all the time. You will never have it as efficient, or as evenly distributing the heat as when the fan is running all the time!


The duration for the time delay that I mentioned last night were guestimates. Today, I put a stop watch on it and noticed that it took 2 minutes 45 secs to start the fan after burner ignition and 5 min 30 sec for the fan to stop after the burner turned off. I gotta get some one to help me see if its still blowing hot at the time when the fan turns off.

I don't under stand how running the fan all the time makes it more efficient, when the fan is running and the burner is off, it is blowing cool air in from the basement. I understand how having the fan run all the time keeps the temperature even but bringing in cold air just after I warmed the house up seeps to very in efficient. Also, on the furnaces I remember from other houses I lived in, I never remember the fan running all the time and besides, it seems like it was just burn out the motor faster by having it run all the time. Who knows...maybe cycling the power to the motor multiple times a day will end up killing it faster.

I may try your suggested experiment with the cover off a little be later this after a Home Depot run while this stuff is still fresh in my head to gain a better understanding of the how this thing works but for now, I'm satisfied with its operation. I think?



yuri said:


> You can safely set it at 150 deg. I replaced hundreds of those back in the 70s and 80s and would set them at 150. The heat exchanger is literally so thick and heavy that nothing short of a bomb could hurt it. Do the random sampling of CO on different days (cooler, hotter and windy and non-windy) so you get a good representative sample and then you can feel safer.


Yuri, what did you replace them with and do you have a suggestion that I could use to replace that old controller? If the exchanger is so thick, do you think its made of cast iron? Once the water patterns change, I will measure the CO again. Yesterday during my test it was cold, wet with little wind. Today its cold cloudy with no wind.


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## yuri (Nov 29, 2008)

L4064 control depending on the insertion length. Some are 5", 8" or 11". It is steel as cast iron is only used in boilers. Too brittle for furnaces. Americanhvacparts.com seems to have a lot of goodies.

http://customer.honeywell.com/Business/Cultures/en-US/Default.htm

Go to homes category then residential combustion then relays and controls then limit controls and then find it. Linking n/w/p today on their site

http://www.americanhvacparts.com/fanandlimit_search.htm

You have to be VERY careful with the new control as it has a jumper between the fan side and the limit side which must be broken off/removed. If not then 120 volts will get shot into ole Betsy's millivolt side and blow her to bits. Once you start fooling around with that old millivolt wiring you may end up with NO heat as it is corroded and difficult to get working in a new control. Need 100% clean bare and TIGHT connections. The new control has push in tabs which are NOT easy to make a millivolt system work with. Is designed mostly for 24volt and 110 volt usage.


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## how (Feb 26, 2011)

There are many facters for or against continuous fan over intermitant fan use but mostly the possible effiency gain is with getting to utilize heat that you are paying for that would otherwize be going up your chimney. Simply put,the delays in how long it takes for the fan to turn on is the time that usable heat is going largely un used up your chimney. The same thing occurs with the useable stored heat in your heat exchanger after the fan goes off.
The current time delays for your fan on & off times (at the 150F setting) sound normal for your type of furnace. So you can leave it as it is to get your intermitant use, return the lever to the left for continuous use but although a new combination control will be available at any Hvac supply house, maybe this is a place to leave sleeping dogs alone.


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## vcheez (Jul 12, 2010)

how said:


> There are many facters for or against continuous fan over intermitant fan use but mostly the possible effiency gain is with getting to utilize heat that you are paying for that would otherwize be going up your chimney. Simply put,the delays in how long it takes for the fan to turn on is the time that usable heat is going largely un used up your chimney. The same thing occurs with the useable stored heat in your heat exchanger after the fan goes off.
> The current time delays for your fan on & off times (at the 150F setting) sound normal for your type of furnace. So you can leave it as it is to get your intermitant use, return the lever to the left for continuous use but although a new combination control will be available at any Hvac supply house, maybe this is a place to leave sleeping dogs alone.


Interesting comments on efficiency of heaters with fan continuous vs intermittent. These are things I never really though of until a week ago. Last month my gas bill was $39 so its not really hurting the pocketbook too much but I don't want to throw money away either. I'll have to experiment with the different scenarios to see what works better. On the 150 setting, does this mean that the air coming from the registers is hotter?



yuri said:


> You have to be VERY careful with the new control as it has a jumper between the fan side and the limit side which must be broken off/removed. If not then 120 volts will get shot into ole Betsy's millivolt side and blow her to bits. Once you start fooling around with that old millivolt wiring you may end up with NO heat as it is corroded and difficult to get working in a new control. Need 100% clean bare and TIGHT connections. The new control has push in tabs which are NOT easy to make a millivolt system work with. Is designed mostly for 24volt and 110 volt usage.


I wish I knew a guy like you in my area to perform the upgrade. I think I will just live with things the way they are. I will kick myself if I end up breaking something that seems to be working fine. Winter is just starting and mama is not gonna be happy if I destroy the furnace tinkering around. At least I have this info for reference.
You guys have been very helpful, taught me a few things and helped me to ensure the safety of my family.

Thanks, VC


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## vcheez (Jul 12, 2010)

biggles said:


> Nice unit..........:thumbsup: any chance getting that black cover off that round controller there that is your fan control and hi limit...picture...want to see the inside.maybe a new stat and we'll keep it simple will give you more consistant cyclying..so you don't have to talk to it.....it's 40F in NYC this morning and the model numbers off that black cover .there should be a adjustable slide bar within there set it up to 150F for now if its not there...just saw the first pix its at 95F go to 150F 2 wire stat is easy to change no service guy needed we'll help http://www.bestbuyheatingandaircond...2/merchant.mvc?Screen=CTGY&Category_Code=T-MV


Hey biggles,

I was checking out thermostats from the link that you posted. They are more expensive than I thought they would be. Do you have a suggestion for a nice programmable unit that will work on my system? Please let me know. Thx, Vc


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## biggles (Jan 1, 2008)

the limit on using a programable stat is most run off 24Vs or what is called a feed back from the heating signal...yada yada.:wink:..on that just explaining it..why yours is different being a millivolt type.you could use a 24V digital stat with a LED screen on yours,but the addition of a 24V/115V transformer and a 24V relay to isolate that millivolt signal generated from the pilot flame... has to happen with the stat install..check www.Grainger for this stat ...#4YZ38.. and prices i don't see many millivolt programables.....not having a 24V system... batteries will power the stat for millivolt controls limiting your selections...how did you do setting the dial temp control up is the fan cycling off after it heats the place?catch you latter...NOTE if you do purchase a stat anyplace it has to say "for use with a millivolt system" on the box.the type you want is one that has sleep/wake/leave/return #3DG27 settings both with temp and times for those California winters!might consider adding that TR and relay easy ... we can talk you thru it and don't worry you won't blow your place up...consider it..


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## vcheez (Jul 12, 2010)

biggles said:


> the limit on using a programable stat is most run off 24Vs or what is called a feed back from the heating signal...yada yada.:wink:..on that just explaining it..why yours is different being a millivolt type.you could use a 24V digital stat with a LED screen on yours,but the addition of a 24V/115V transformer and a 24V relay to isolate that millivolt signal generated from the pilot flame... has to happen with the stat install..check www.Grainger for this stat ...#4YZ38.. and prices i don't see many millivolt programables.....not having a 24V system... batteries will power the stat for millivolt controls limiting your selections...how did you do setting the dial temp control up is the fan cycling off after it heats the place?catch you latter...NOTE if you do purchase a stat anyplace it has to say "for use with a millivolt system" on the box.the type you want is one that has sleep/wake/leave/return #3DG27 settings both with temp and times for those California winters!might consider adding that TR and relay easy ... we can talk you thru it and don't worry you won't blow your place up...consider it..


Thanks for the tip. I'll look into Grainger tomorrow for a programmable millivolt controller. 
When I raised the controller temp to 150, my furnace responded well by cycling the fan on and off as the burner turned on. 
It was all good for a day or so but i think the axles on the fan or the squirrel cage need a little TLC. I woke this morning to the nasty sound of motor trying to start that could not. I put on my robe, ran down to the basement, removed the cover of the furnace and gave the motor an ever so slight clockwise twist and it began spinning normally. I then changed the thermostat back to its normal setting of continuous fan until I get a chance to clean up the fan and grease the axles. I had a feeling this old fan was not going to like starting and stopping. I think I can handle cleaning the fan, removing the dust and making sure things spin smoothly. I'm just glad Iwas home when this occurred because the motor could have overheated and caused all sorts of bad problems. Thanks again for your assistance and if you know what else I should do to keep my fan running smoothly, please let me know. Thx, VC


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## biggles (Jan 1, 2008)

the motor is the only thing that might take oil...need a new capacitor for the supply fan availible at Granger....cheap fix.have a old toothbrush with the furnace switch off..brush the motor openings front and back of dust....might have to slide that fan section out to clean the squirrel fins if there just dusty no big deal...here's is what a capacitor looks like http://www.bestbuyheatingandaircond...?Screen=CTGY&Category_Code=c-370vorc ..values stamped on it when you replace it...Mfd=microfarads rating, 2 wires off 2 wires on and mount it..so the constant fan was the lower setting on the fan limits thats good ...:wink: work that setting anywhere just below 150F its just making hotter air to satisfy the stat setting...quicker. when the main burner comes on that flame is one constant temp to be used according to the supply fan reaction.


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## how (Feb 26, 2011)

Biggies advice is good ( especially for the DIY inclined) but be aware that 90 % of the time you are just putting off a motor change until Christmas or New Years eve.. I never asked you if your two speed motor was direct drive or if you have belts and pulleys.


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## how (Feb 26, 2011)

Whoops, Missed a photo and part of my mind. Take the belt off and see if the squrrell cage rotates easily. If it doesn't then blower bearings need to be looked at. 
A lot of old motors that have not been serviced regularly will choose to die after being lubricated ( If they have not been oiled in years) or when they get switched from intermitant to continuous use.


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## biggles (Jan 1, 2008)

no problemm there..also the motors as most furnaces are are on the return air side so they usually run some what cool with that return air being pulled in.sure remove the belt and spin the motor sheave/pully then spin the pully for the squirrel cage hear anything???:huh: rumbling and quick sops especially on that motr...then after a normal cycle of heat shut the furnace switch pop the fan cover section.....and put your hnd right on the motor body slightly warm but if you can't keep your hand on it your looking at a motor change out....and if your handy we'll talk you thru that one....:thumbsup:


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## vcheez (Jul 12, 2010)

biggles said:


> the motor is the only thing that might take oil...need a new capacitor for the supply fan availible at Granger....cheap fix.have a old toothbrush with the furnace switch off..brush the motor openings front and back of dust....might have to slide that fan section out to clean the squirrel fins if there just dusty no big deal...here's is what a capacitor looks like http://www.bestbuyheatingandairconditioning.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=c-370vorc ..values stamped on it when you replace it...Mfd=microfarads rating, 2 wires off 2 wires on and mount it..so the constant fan was the lower setting on the fan limits thats good ...:wink: work that setting anywhere just below 150F its just making hotter air to satisfy the stat setting...quicker. when the main burner comes on that flame is one constant temp to be used according to the supply fan reaction.


Hey biggles,

I did not see a capacitor. Where is it located. I clicked the link that you posted but it led to a page that was blank. If you could recheck that link, that would be great. If I can see what the capacitor looks like, I might be able to spot it once I slid the motor and fan assembly forward.

Thx, VC


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## yuri (Nov 29, 2008)

It has no capacitor. Belt drive motors don't. Direct drive do. I would buy a good quality Honeywell Focus Pro tstat at HDepot. A set of batteries can go 2-3 yrs on the better quality tstats. I don't run mine off 24 volts. Not hard to change batteries every 2-3 yrs and the newer ones have a LO BAT indicator. There is no specific millivolt programmable thermostat. The old mercury ones had no heat anticipator for millivolt use vs a heat anticipator for 24v use. You can use the one I told you. When you get a new furnace or heat pump they can run some more wires to the tstat and use it from 24 volts from the furnace but for now I would just use batteries. DO NOT ever use rechargeables as the voltage drops and damages them. Good Energizers is all you need.


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## biggles (Jan 1, 2008)

like noted maybe there isn't one...thought i saw them actually mounted on the motor body as shipped...:huh: with a cover...try that link again http://www.bestbuyheatingandairconditioning.com/capacitors.htm


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## vcheez (Jul 12, 2010)

biggles said:


> the motor is the only thing that might take oil...need a new capacitor for the supply fan availible at Granger....cheap fix.have a old toothbrush with the furnace switch off..brush the motor openings front and back of dust....might have to slide that fan section out to clean the squirrel fins if there just dusty no big deal...here's is what a capacitor looks like http://www.bestbuyheatingandairconditioning.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=c-370vorc ..values stamped on it when you replace it...Mfd=microfarads rating, 2 wires off 2 wires on and mount it..so the constant fan was the lower setting on the fan limits thats good ...:wink: work that setting anywhere just below 150F its just making hotter air to satisfy the stat setting...quicker. when the main burner comes on that flame is one constant temp to be used according to the supply fan reaction.


I cleaned up the fan and most of the dust tonight. I oiled the motor and blower axles. The fan still seems to have difficulty starting after a stop. I cycled the power a few time and it was not consistent on starting up so I left in the continuous mode. I'm not as concerned about running the fan 24 x 7 because I just closed this little make up air inlet that is in the basement. I think that will prevent the cool air from coming back up into the house and making my heater work more than it needs too. Of course, it might also reduce the amount of fresh air that comes into the house. The fan belt is severely cracked so this weekend when I have a little more time to play around, I'll go out and grab a couple of belts. I hope HDepot sells them. I also would not mind purchasing a new motor. Where would I go to find a motor like this? This baby is old and like one of the forum members posted last week, its not grounded. The motor is plugged into one of my remaining knob and tube receptacles. I think, I will run a new circuit that has a ground terminal. I'm hoping a new motor would be made for 3 wire connection.
Motor Specs:
Model 5KH45AB1738BX
HP = 1/4
Type = KH
RPM = 1725
Current = 3.5A
Voltage = 115VAC 60Hz Single Phase
Time Rating = Cont
Temp Rise = 40C
GEI = 435



yuri said:


> I would buy a good quality Honeywell Focus Pro tstat at HDepot. A set of batteries can go 2-3 yrs on the better quality tstats. I don't run mine off 24 volts. Not hard to change batteries every 2-3 yrs and the newer ones have a LO BAT indicator. There is no specific millivolt programmable thermostat. The old mercury ones had no heat anticipator for millivolt use vs a heat anticipator for 24v use. You can use the one I told you. When you get a new furnace or heat pump they can run some more wires to the tstat and use it from 24 volts from the furnace but for now I would just use batteries. DO NOT ever use rechargeables as the voltage drops and damages them. Good Energizers is all you need.


Would this Honeywell Focus Pro tstat from HDepot be a direct replacment for my old outdated unit? I just have two wires than run down from my tstat to the furnace. I cant figure out exactly how its wired into the furnace controls. I'll have to take a few photos tomorrow and post them for you guys. There are couple of wire-nuts that connect the tstat wires to some of the furnace control wires and I can't tell where they are connected because the cables run into some flexible conduit. If the unit that you have suggested, is a direct replacement, I won't worry about it but I would like to figure out what's going on with the wiring mess.

*Old Motor*








*
Basement Make up Air Inlet for Furnace*


----------



## yuri (Nov 29, 2008)

1) Motor - HDepot may have them if not then Acklands/Graingers. Get a new pulley too. 3.5" x .5 inch shaft. Belt size may change due to diameter of new motor. Make sure the fan turns in the proper direction when done and buy a reversible motor.

You ABSOLUTELY need a grounded circuit for your new furnace so it is time to do it. Will not work properly w/o a dedicated ground as the circuit board checks for that.

2) Tstat is fine with your wires. Hook up to R and W and it max no difference which wire goes to what terminal.


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## vcheez (Jul 12, 2010)

yuri said:


> 1) Motor - HDepot may have them if not then Acklands/Graingers. Get a new pulley too. 3.5" x .5 inch shaft. Belt size may change due to diameter of new motor. Make sure the fan turns in the proper direction when done and buy a reversible motor.
> 
> You ABSOLUTELY need a grounded circuit for your new furnace so it is time to do it. Will not work properly w/o a dedicated ground as the circuit board checks for that.
> 
> 2) Tstat is fine with your wires. Hook up to R and W and it max no difference which wire goes to what terminal.


Here is a link from amazon. Do you think this one will work?
It's kinda big for my preference but its not too expensive.
http://www.amazon.com/Honeywell-TH6110D1021-FocusPro-Programmable-Thermostat/dp/B000UQ7T58


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## yuri (Nov 29, 2008)

perfect. I sold lots of them. very easy to follow install info and programming, unlike others.


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## pete0403 (Dec 22, 2010)

VC,

Great thread...a very interesting read. Thanks for posting all the pictures and info. 

I may have missed it but did you ever compare your $50 CO monitor to the commercial grade one with calibration gas? I'd be interested to see how accurate the cheapie is.


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## biggles (Jan 1, 2008)

idea on that motor prices...check the tag for that FRAME size 48Y on this one,but the mounting bracket with the clips is the frame not the plate with the bolts in it...amps are going to be higher and BX fitting into the electrical :wink: on the stat make sure it can run millivolts system 1 or 2 amps over the older one isn't going to call for major wiring update either...:thumbsup: http://www.bestbuyheatingandaircond...Category_Code=m-115vbdm&Product_Code=MOT6002D that fan section slides out might want to take it outside and hose it down with a dry pre spray of cleaner fantastic or something and it will look brand new..


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## vcheez (Jul 12, 2010)

yuri said:


> perfect. I sold lots of them. very easy to follow install info and programming, unlike others.


Hey yuri,

I bought this one instead. It's a Honeywell RTH6350. HDepot did not have the Focus line available so I bought the RTH6350 which is suppose to be a newer version. Besides, if it doesn't work, at least I can return it for a full refund. Anyways, I have attached a photo from the manual. I tried to take a photo of the actual terminal strips but I could not get my camera to focus. There are many terminals. There is currently a jumper between R and Rc. Should I disconnect the jumper when I connect my current pair conductors to W & R? Please let me know what you think.

I'm gonna hook it up tomorrow. Thx, VC
*
Page from Manual for RTH6350*









*New Thermostat*


----------



## vcheez (Jul 12, 2010)

pete0403 said:


> VC,
> 
> Great thread...a very interesting read. Thanks for posting all the pictures and info.
> 
> I may have missed it but did you ever compare your $50 CO monitor to the commercial grade one with calibration gas? I'd be interested to see how accurate the cheapie is.


Thanks. I had a great time posting and hearing the feedback from the forum members. I learned a lot and also feel a lot more safer about my furnace for the winter.

I have not yet compared the 50PPM Co vs. is my new monitor and the lower priced unit. I gave my new bottle of CO to one of my technicians and I can't find it in his service van. Thanks for reminding me. I got so excited about not detecting any CO with my new monitor that I forgot to complete my testing. I will grab the CO cylinder from work on Monday and try my experiment that I evening. I'll make sure to post the results to let you know if the low cost unit responds similarly to the commercial unit.



biggles said:


> idea on that motor prices...check the tag for that FRAME size 48Y on this one,but the mounting bracket with the clips is the frame not the plate with the bolts in it...amps are going to be higher and BX fitting into the electrical :wink: on the stat make sure it can run millivolts system 1 or 2 amps over the older one isn't going to call for major wiring update either...:thumbsup: http://www.bestbuyheatingandaircond...Category_Code=m-115vbdm&Product_Code=MOT6002D that fan section slides out might want to take it outside and hose it down with a dry pre spray of cleaner fantastic or something and it will look brand new..


Thanks for the tip on the motor. It looks like you did the research for me. I have my electrical engineer buddy stopping by tomorrow morning to come help me find a substute but the motor shown in the link looks like it will work. I just wanna make sure that it will work. $186 + $34 is a lot of money for me to spend online where its hard to return items. I don't know of a local store that I can purchase a blower motor like this so I will have to make sure that to order an equivalent motor that will drop right into place.

Thx, VC

Thx, VC


----------



## yuri (Nov 29, 2008)

- leave the jumper in place and connect to R and W

- I am in Canada but hear that Grainger(s) is a big outfit in the US to buy motors and parts from and sells to the public?


----------



## bob22 (May 28, 2008)

Why not try a local electric motor shop; I googled and got 
http://www.easa.com/node/912
as an example.
My local motor place sold me new blower motor much cheaper than others I saw.


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## biggles (Jan 1, 2008)

ask your engineer friend about maybe boosting the HP on the new one 1/2 hp maybe or 1/3rd little more umffff:wink: nice simple stat unit won't know itself...definitly close off that return on the basement floor so you pull the true heated space.....by the time were're done here you going to know more then we do :thumbsup:


----------



## how (Feb 26, 2011)

If you decided that you only want a temp controlled fan operation in your furnace, a single speed motor would be cheaper.


----------



## vcheez (Jul 12, 2010)

biggles said:


> ask your engineer friend about maybe boosting the HP on the new one 1/2 hp maybe or 1/3rd little more umffff:wink: nice simple stat unit won't know itself...definitly close off that return on the basement floor so you pull the true heated space.....by the time were're done here you going to know more then we do :thumbsup:


My buddy was a no call no show so I didn't get too far with motor replacement today. I saw this one at the following ling that might be nice:
http://www.johnstonesupply.com/stor.../split-phase/open-dripproof//prods88-630.html

What would be the advantage of having greater horsepower? Please explain.



bob22s said:


> Why not try a local electric motor shop; I googled and got
> http://www.easa.com/node/912
> as an example.
> My local motor place sold me new blower motor much cheaper than others I saw.


Thanks for the tip on finding a local motor house. I didn't even think of that. There are several in my town. I'm gonna try Johnstone Supply. I hope they are opened on Saturday's but I doubt it. The store that you suggested looks good and will probably have better pricing but it is really far away from my town. I think its about a 2 hour drive to Merced from Santa Clara.



how said:


> If you decided that you only want a temp controlled fan operation in your furnace, a single speed motor would be cheaper.


I just want the new motor to operate like it does now without me having to help the motor start by spinning the axle if it needs to be restarted. I can't think of a reason for more than one speed since I currently only run the fan at one speed.


----------



## how (Feb 26, 2011)

Sorry..got tripped up with your starting posting of the motor running 24/7 which sounded like a 2 speed. Just go with a single speed.
You can't expect much of a lifespan out of the exchanger of a furnace of this age so I'd just stick to the hsp it came with. Ground that new motor for sure. Remember to set up the belt tension loosely (at least 2" or more of bounce on the belt) because you are only pushing air and you might as well try to keep the lateral belt pressure low for those old fan bearings. If the pulley/ motor position doesn't seem to line up with the main blower pulley then remember that the base of your new motor is offset and can be removed & turned around to provide an alternative motor position.
oh and don't oil the shaft on this furnace as it's meant as a dry slide whereas oil can mix with dust and create a binding internal mess over time that is hard on bearings, shaft & motor.
Cheers


----------



## vcheez (Jul 12, 2010)

pete0403 said:


> VC,
> 
> Great thread...a very interesting read. Thanks for posting all the pictures and info.
> 
> I may have missed it but did you ever compare your $50 CO monitor to the commercial grade one with calibration gas? I'd be interested to see how accurate the cheapie is.


Hi Pete,

I finally ran my test with my 50ppm CO calibration gas with my commercial grade monitor vs. my $50 dollar unit and like yuri mentioned at the beginning of this thread, the $50 dollar unit must be made for catostrophic releases of CO because it did not alarm at all after about 1 minute of exposure with a flow rate of 1 liter/minute of 50PPM CO. The commercial unit responded within 3 to 5 seconds. Too bad the comercial unit is not priced so it could be affordable to the general public. The one I purchased was around $350. The cost of putting these in every room would be quite staggering for most folks including me. Since I'm in the gas detection business I got a discounted price and knew where to find a good affordable unit. Luckily its jut me and mama living in this big house and I'm running my little unit all night long in front of the register in my bedroom. So far I have not measured any levels on all nights except for the one night that it was raining heavily. I observed a peak of 6 ppm that occurred at some point during the night. That reading is fairly low and was not high enough to activate the audible alarm but I will look to see if it was real if I see that kind of reading again during the next strong rain. It's been a pretty dry fall so far. We usually get most rain during the winter and spring.


----------



## vcheez (Jul 12, 2010)

how said:


> Sorry..got tripped up with your starting posting of the motor running 24/7 which sounded like a 2 speed. Just go with a single speed.
> You can't expect much of a lifespan out of the exchanger of a furnace of this age so I'd just stick to the hsp it came with. Ground that new motor for sure. Remember to set up the belt tension loosely (at least 2" or more of bounce on the belt) because you are only pushing air and you might as well try to keep the lateral belt pressure low for those old fan bearings. If the pulley/ motor position doesn't seem to line up with the main blower pulley then remember that the base of your new motor is offset and can be removed & turned around to provide an alternative motor position.
> oh and don't oil the shaft on this furnace as it's meant as a dry slide whereas oil can mix with dust and create a binding internal mess over time that is hard on bearings, shaft & motor.
> Cheers


I went out and bought a 1/2 HP unit at Grainger yesterday. At first I picked up a 1/4 HP unit but it was so tiny in comparison to the 1/2 HP unit that I exchanged it for the 1/2 HP unit that is just about the same size as my existing 1/4HP motor. 
This weekend, I plan to install the new fan and rewire the controller and motor. I need to draw a little wiring diagram to try understand what I'm rewiring because the way that it is currently wired is not cool and there are 115V splices with electrical tape, ungrounded not in a j-box. I ain't no electrician and even though it has been this way for probably longer than I have been alive, I know it's not right nor up to code. Anyways, in the first photo below, can some one please tell me what is the device on the left and what is its purpose. I think it maybe a solenoid that is activated by the thermopile voltage but i have a wiring diagram that makes me think its a burner motor whatever that is. I'm trying to figure out what the wiring is doing. 
Also please let me know if the higher current load of the 1/2HP motor could be too much for controller mercury switches. The wire is 12 gauge so I know it is appropriately sized for the current at 115V of 7.2A but I just wanna make sure since the existing 1/4HP motor only draws 3.5A.

Thanks in advance, VC

*Controller with Cover Off and Other Stuff*









*Controller Schematic*









*New Motor*








*
Motor Specs*









*Wiring Mess*









The 120Volt is on the left with the electrical tape on it.


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## beenthere (Oct 11, 2008)

Take that 1/2 HP back, and get a 1/4 HP. A new 1/4 HP will be plenty, of motor for your old furnace. Its not like your trying to increase your air flow so you can blow air into your neighbors house. Are you?

The 1/2 HP motor won't move anymore air then a 1/4 HP at the same RPM. You would have to turn the motor pulley in to increase blower wheel speed.


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## how (Feb 26, 2011)

Go with a 1/4 hsp if that's what you had in there (as beenthere says). 
Your just pushing air. 
That channel lock on your 1/2 hsp shaft is also just another complexity over what you had.


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## yuri (Nov 29, 2008)

if I wuz U I would leave that old fan control and limit with the mercury switches TOTALLY alone. as soon as you monkey with it you will have NO heat as looking at old millivolt wiring is enough to break it or cause a poor connection. trust me you don`t want to go there. get a .25 hp motor and hook it up with some better wiring and call it a day. the .5 will be heavier and cause vibration etc. motors are half the weight now then back when that unit came across the pond with Columbus. the hp is the same and that is all that matters.


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## vcheez (Jul 12, 2010)

yuri said:


> if I wuz U I would leave that old fan control and limit with the mercury switches TOTALLY alone. as soon as you monkey with it you will have NO heat as looking at old millivolt wiring is enough to break it or cause a poor connection. trust me you don`t want to go there. get a .25 hp motor and hook it up with some better wiring and call it a day. the .5 will be heavier and cause vibration etc. motors are half the weight now then back when that unit came across the pond with Columbus. the hp is the same and that is all that matters.


Ok guys. I will take back that 1/2 HP motor. I've been following your advice so far and things have been working fine so I'm not gonna change now. I thought I would get your opinions before pulling the trigger. 
I'm not gonna mess with the millivolt wiring but the power to the blower fan runs through the mercury switch on the controller and I will need to run a ground wire for the new fan. I was going to try to feed the new ground wire through the existing flexible conduit. Maybe I should just try to run an independent ground wire to the new fan.
It's starting to get cold here and everyone is gonna be mad a daddy If I got spend the Christmas money on a new heater.

PS can someone tell me what that piece of equipment on the left is. I'm talking about the unit with the four wires connected to it. I think it could be a solenoid.

Thx, VC


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## beenthere (Oct 11, 2008)

Gas valve. The device to the right is the regulator.


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## yuri (Nov 29, 2008)

run an independent ground wire is the best way.:thumbsup:


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## vcheez (Jul 12, 2010)

yuri said:


> run an independent ground wire is the best way.:thumbsup:


Thanks for the advice. I tied into the existing wiring and avoided messing with the existing wires and ran the independent ground wire as you suggested. I also cleaned up the 120VAC splice point and put it in a j-box. I'm still not too thrilled about using the existing wires because I fear that the insulation will come off and cause a short but at least since I have the ground wire the short will go to ground and pop the circuit breaker.

This new motor was humming and is actually vibrating a little more and is a little bit louder but it does not need a kick start to get going. I think it is rotating much faster because its blowing out a lot more air in the house.

I'm really glad you guys talked me out of putting in the 1/2HP motor. That would have been way over kill.
I think I'm done with this project for now so I don't think you'll be hearing from me on this one anymore unless that old funky controller fails. Thanks for all the good advice and direction. I can sleep a little better this winter.:thumbup:

*New Motor With Independent Ground Wire*








*
Close Up of Motor*









*New j-box*


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## biggles (Jan 1, 2008)

max'd 1725 RPMs on that new one if it is little noisey and the belt is flush up to the top of those sheaves on the motor:wink: 1/4 to 1/2 turn to drop the belt a little down into the sheave won't kill to much air and quiet it up try it to test the difference...nice job save a ton of $$$.any chance of getting an amprobe on the wires see wh the amps are with the panels up see how close you are to the tagged amps....tip...wire tie the wires and green ground off the motor base from vibration....have a good holiday


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## how (Feb 26, 2011)

That picture looks like you have an aluminum split pulley on that motor. If so, swapping it out for a steel split pulley will also drop the vibration and sound level.


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## vcheez (Jul 12, 2010)

how said:


> That picture looks like you have an aluminum split pulley on that motor. If so, swapping it out for a steel split pulley will also drop the vibration and sound level.


 The guys at Grainger only brought out the aluminum one. The pulley on my old motor looks like steel. That motor was so old that i think it was built before aluminum was invented. ;-) I tried to pull it off of the shaft and it didn't budge. I didn't give it too much effort but I'll try again to tonight and then see if I can clean it up and reuse it. Why will a steel pulley be quieter?


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## how (Feb 26, 2011)

Side by side tests of new aluminum and steel split pulleys always come out in favour of the steel when it comes to lower voice and vibration. I have just assumed it was because the steel castings are truer than the aluminum. They do cost twice as much but I think an extra 10 bucks is worth the quality of life improvement.


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## biggles (Jan 1, 2008)

old pully...WD40 it on the top and back shaft...take a adjustable wrench and slide it between the motor mouting bracket and the pully and burp it off or he largest screw driver around and do the same between the pully and the motor brearing hamer it down and it will move it out onto the shaft


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## vcheez (Jul 12, 2010)

biggles said:


> max'd 1725 RPMs on that new one if it is little noisey and the belt is flush up to the top of those sheaves on the motor:wink: 1/4 to 1/2 turn to drop the belt a little down into the sheave won't kill to much air and quiet it up try it to test the difference...nice job save a ton of $$$.any chance of getting an amprobe on the wires see wh the amps are with the panels up see how close you are to the tagged amps....tip...wire tie the wires and green ground off the motor base from vibration....have a good holiday


Hey biggles,

I borrowed my buddies amp clamp and it was pretty close to the listed current. The baseline that I measured with the clamp was around 0.17A so the reading of 5.097A was pretty close to the listed value of 4.8A. My buddy told me that the way that the amp clamp works with the fluke meter is that you have to set it on the ac mv setting.

I don't understand how spreading out the pulley and lowering the belt will make it spin slower and quieter. It seems like this would make it spin faster. I will try playing with the pulley this weekend and I will also take your advice and tie wrap the ground wire and the power cord off of the motor platform.

*AmpClamp Reading*


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## beenthere (Oct 11, 2008)

By opening up the pulley. The belt spins at a slower RPM, which in turn spins the blower will slower.

A 2" motor pulley turning an 8" blower wheel is a 4:1 ratio. So a 1725 motor on that set up would only be turning the blower at 431RPMs.
A 3 " motor pulley would be 646 RPM.


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## vcheez (Jul 12, 2010)

biggles said:


> max'd 1725 RPMs on that new one if it is little noisey and the belt is flush up to the top of those sheaves on the motor:wink: 1/4 to 1/2 turn to drop the belt a little down into the sheave won't kill to much air and quiet it up try it to test the difference...nice job save a ton of $$$.any chance of getting an amprobe on the wires see wh the amps are with the panels up see how close you are to the tagged amps....tip...wire tie the wires and green ground off the motor base from vibration....have a good holiday


Thanks for the tip. I opened up the pulley a bit and just like you said, the RPMs dropped a bit and so did the noise. The current dropped a bit too. I also, tied up the wires to get them off of the base. I'm not sure what the difference is since they are still vibrating because they are mounted to the motor but since you have the experience, I just do what is suggested. 

*Motor with Wires Tied Up*









*Current Measurement*


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## beenthere (Oct 11, 2008)

You can probably open that pulley another full turn, and get the amp draw down to around 3 or 3.5, and then check temp rise.


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## how (Feb 26, 2011)

Biggies suggested turning that split pulley one 1/4 or 1/2 turn out.

My questimate looking at your your picture says that this split pulley has been slowed down a lot more than that. 
You will get a quieter sound but the operating temp of your furnace will be probably be 10 -12 degrees hotter than it was. That means a loss of efficiency and a harder wear factor on old parts and the exchanger.
Depends on what your priorities are.
I would still try a steel split pulley so you'd get some quiet at the same temp that this unit has been running with for 45+ years.


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## vcheez (Jul 12, 2010)

how said:


> Biggies suggested turning that split pulley one 1/4 or 1/2 turn out.
> 
> My questimate looking at your your picture says that this split pulley has been slowed down a lot more than that.
> You will get a quieter sound but the operating temp of your furnace will be probably be 10 -12 degrees hotter than it was. That means a loss of efficiency and a harder wear factor on old parts and the exchanger.
> ...


I wasn't exactly paying attention to what I read from biggies and I was thinking that he meant 1/4" to 1/2" instead of 1/4 to 1/2 turn. Nevertheless, this what is what it looked like before. I remember the belt was riding low in the pulley and I didn't realize that there was a reason for that. I think were the pulley is now is similar to what I had before. I will check it out to see if tweaking it changes things much. I was happy to reduce the current draw of the motor because I did not replace the old wire in the controller and I am a little concerned about the ancient insulation melting if the current is too high. My next weekend project will might be to salvage my old steel pulley and to clean it up. 

VC


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## biggles (Jan 1, 2008)

Sorry didn't read this till tonight..i took it the belt was up on the pully flash with the tops of the sheaves and you had vibration i ment a 1/4 turn to 1/2 turn from the loosening the allen key flat whats the amp tag on the motor.tightening the wires up was to get them off the frame base....sure they will vibrate from the motor run but not on the base....your never going to actually change a motors speed as in hi/med/lo with a sheave adjustment it's only to take slight rpms and amps off.where was the belt in the sheave before the adjustment..main part of the belt is the V part where you want the sheave to make a good grab..flush up is always a good place to start then drop it down is flush up the actual speed selected for the unit is somebody else to kick in with on that one..Question whats with the AC millivolt reading


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## vcheez (Jul 12, 2010)

biggles said:


> Sorry didn't read this till tonight..i took it the belt was up on the pully flash with the tops of the sheaves and you had vibration i ment a 1/4 turn to 1/2 turn from the loosening the allen key flat whats the amp tag on the motor.tightening the wires up was to get them off the frame base....sure they will vibrate from the motor run but not on the base....your never going to actually change a motors speed as in hi/med/lo with a sheave adjustment it's only to take slight rpms and amps off.where was the belt in the sheave before the adjustment..main part of the belt is the V part where you want the sheave to make a good grab..flush up is always a good place to start then drop it down is flush up the actual speed selected for the unit is somebody else to kick in with on that one..Question whats with the AC millivolt reading


I think its adjusted to a nice speed now. It's a bit quieter and drawing a little less current. The AC milivolt reading is actually equivalent to the same reading in amps. My buddy loaned me his amp clamp to connect to my fluke meter. The instructions said to put the fluke on the milivolt range and the reading that is read on the display is actually the current in amps. I'm not sure how it works but my bud is an electrical engineer and I just take his word for it.


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## biggles (Jan 1, 2008)

do you get the same numbers in the milli amp setting never saw that meter used like that reading amps....just wondering:wink: what was the amp rating on that new motor


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## vcheez (Jul 12, 2010)

biggles said:


> do you get the same numbers in the milli amp setting never saw that meter used like that reading amps....just wondering:wink: what was the amp rating on that new motor


If you put it on the milliamp setting, the Fluke meter gives an error. The amp clamp that we were using converts voltage to current based on the inductance measured on the hot line. I could measure it in series on the amp setting to get a more accurate reading.


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## biggles (Jan 1, 2008)

30 yrs in the industry never saw that did milliamps on thermocouples testing..but line amps..:huh:..always used clamp type amp probes....see how much i don't know.....:wink: work looks :thumbsup: mint


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## how (Feb 26, 2011)

Hey Biggles
What circumstances had you milli amp testing a thermocouple instead of dcmv?


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## vcheez (Jul 12, 2010)

Hi Guys,

Another year has gone by and my beast of a furnace is still churning away. I had my HVAC mechanic buddy inspect it and he said that he was amazed at what great shape it is in. He came over to try to sell me a new one but said that he will gladly help me service this one. 
I've noticed that the gas valve sticks when the cold season first starts. Even last year, towards the end of the cold season here in the SF Bay Area, I noticed that the heat would not come on sometimes. I would then go down to the basement and tap on the gas valve in the position that I have shown here. 








A couple of quick taps and the gas valve opens. My mechanic said that he would replace the gas valve for me but I need to find it or specify it and he would install it. He is only about 40 years old and like most union trained youngsters, only works on modern equipment. I was wondering if any of the oldtimers or experts here have a suggestion of gas valve that will replace mine. 

Last year when I first posted photos of my furnace, I had to explain that this furnace was not pumping carbon monoxide into my house. I have a commercial grade CO monitor that gets calibrated on a regular basis and I'm certain that it is not pumping carbon monoxide into my house. I realize that those who were concerned with me being exposed to CO were just trying to let me know the dangers but I have determined that the a CO leak is not occurring at this time and to make sure, I have the commercial grade CO monitor running 24 x 7. 

Any help or advice about a replacement gas valve would be appreciated. Thanks in advance, VC


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## beenthere (Oct 11, 2008)

http://www.pexsupply.com/Weil-McLain-510-811-641-Thermopile-Gas-Valve-for-PFG-Boilers-PFG-6-7

The above valve will work. You can search for Thermopile gas valves and come up with a fair number of links.

How big is your house again. thats a huge furnace for an area that I thought had a some what warm climate.


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## how (Feb 26, 2011)

OK, I'm pleading laziness for not going through 7 Pages of postings again.

Beenthere.. What made you think the gas valve was thermopile driven? 
Just asking because of the amount of 6 & 12 volt transformers that I've seen attached to dinosaurs, not to mention the look of the extra limit load through that gas valve.


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## vcheez (Jul 12, 2010)

beenthere said:


> http://www.pexsupply.com/Weil-McLain-510-811-641-Thermopile-Gas-Valve-for-PFG-Boilers-PFG-6-7
> 
> The above valve will work. You can search for Thermopile gas valves and come up with a fair number of links.
> 
> How big is your house again. thats a huge furnace for an area that I thought had a some what warm climate.


Thanks for the tip. I didn't realize that thermopile can generate 24VDC. Are you sure the suggested valve will work with thermopile supplied voltage? $300 is a lot to spend to know for sure.

My house is around 2000 sq ft. This heater brings the house from cold to warm in about 2- 3 minutes. Not efficient, but damn comfortable.

Thank in advance, VC


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## vcheez (Jul 12, 2010)

how said:


> OK, I'm pleading laziness for not going through 7 Pages of postings again.
> 
> Beenthere.. What made you think the gas valve was thermopile driven?
> Just asking because of the amount of 6 & 12 volt transformers that I've seen attached to dinosaurs, not to mention the look of the extra limit load through that gas valve.


I can see a thermopile down in the pilot light but it could be a thermocouple. I can't tell the difference. There are no tranformers on this dinosaur that I can see. Where should I put my voltmeter to measure the thermopile output and what is the expected voltage for a thermopile?

Thanks in advance, VC


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## beenthere (Oct 11, 2008)

Looking at it closer. It does look like a thermocouple system. A thermopile will have 2 wires coming from it.


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## how (Feb 26, 2011)

A thermopile will generate about 1/2 volt DC. A Thermopile will be a 1/2 " in diameter whereas a thermocouple will be less than a 1/4"
Thermopiles are usually connected by two wires that are sometimes covered by a spiral wrap that can make them look like one wire. They can have ends that are seperate or ends that screw into gas valves that are identical to thermocouples. I think I saw a spiral wrapped line on the page three photo but it didn't look connected to anything?
Put your meter leads on the black wires connections on the gas valve. Start with a setting above 24V AC. If you don't get 24V,12V or 6V then switch to checking for around 1/2 DCMV.


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## vcheez (Jul 12, 2010)

how said:


> A thermopile will generate about 1/2 volt DC. A Thermopile will be a 1/2 " in diameter whereas a thermocouple will be less than a 1/4"
> Thermopiles are usually connected by two wires that are sometimes covered by a spiral wrap that can make them look like one wire. They can have ends that are seperate or ends that screw into gas valves that are identical to thermocouples. I think I saw a spiral wrapped line on the page three photo but it didn't look connected to anything?
> Put your meter leads on the black wires connections on the gas valve. Start with a setting above 24V AC. If you don't get 24V,12V or 6V then switch to checking for around 1/2 DCMV.


Thanks for your replies. We only had a couple of days of cold so far. It warmed back up so I have been paying much attention to the heater. I think I'll wait until Xmas Eve and all of the relatives are over.

I measured 174mv between the wires shown in the photo below.










When I turn on my thermostat, I have to put a magnet towards the right side of the gas valve. I hear a click and then the burner ignites. Isn't 174mv kinda low for a thermopile?


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## how (Feb 26, 2011)

If you want to measure the powerpile output, just do it with the wires from the powerpile. It looks like your measuring points are including the thermostat and gas valve electromagnet. Most furnace powerpile gas valves require at least 250 DCMV and above from a powerpile. Make sure your pilot assy flame is enveloping the powerpile for the maximum possible output and that all your related connections (thermostat, mercury & limit controls) are completely tight.


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## vcheez (Jul 12, 2010)

how said:


> If you want to measure the powerpile output, just do it with the wires from the powerpile. It looks like your measuring points are including the thermostat and gas valve electromagnet. Most furnace powerpile gas valves require at least 250 DCMV and above from a powerpile. Make sure your pilot assy flame is enveloping the powerpile for the maximum possible output and that all your related connections (thermostat, mercury & limit controls) are completely tight.


It's been awhile since I've addressed this issue here at the forum. 
Winter is coming again and this old furnace is still working but I need to go down to the basement and tap on the gas valve with a magnet to fire it up. I'm still trying to determine if I need a new thermocouple or if the gas valve requires more voltage than the thermocouple can provide because it is old and is sticking. I'm hoping it's the thermocouple because I think I can replace that easily & safely for a low price. 
I measured 175mv at the thermocouple when its not connected to anything else. Is this enough? When I turn on the thermostat, I measured 130mv at the arrows shown in my last photo. Remember, turning on the thermostat does not open the gas valve. I have to manually assist its opening as I mentioned above. When the thermostat is off, I measured 175mv at the point of the arrows so I know there is not a voltage drop due to poor wiring. Once the gas valve opens and gas is flowing to the burner, I only measure 90mv at the arrow points. I'm wondering if the thermocouple is not producing enough voltage to activate the electromagnets in the valve. I'm suppose I could go buy a larger output thermocouple but I don't want to introduce too much voltage to the electromagnet in the gas valve and damage it. I also have no idea if I need a thermocouple or thermopile and what voltage is needed to open the valve. Thanks in advance, vc


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## danpik (Sep 11, 2011)

thermocouple



thermopile


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## beenthere (Oct 11, 2008)

Your thermopile readings are too low.


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## vcheez (Jul 12, 2010)

Ok. What should the thermopile voltage be? Is the voltage drop normal when the valve is opened. Thanks, VC


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## beenthere (Oct 11, 2008)

You generally don't want to see them less the 500mV. And under load they do drop a lot.


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## biggles (Jan 1, 2008)

you have a thermopile (wires) generator,and a thermocouple (copper capillary tube) to proof the main gas that a flame is present..check all the connection on the generator wiring even the stat a loose connection will pull..but removing the wires and reading are the true generator test..make sure he pilot flame is covering the probe element


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## vcheez (Jul 12, 2010)

Thanks for the advice. One of the problems that I have is that I can't actually see the part of the thermopile that is in the flame. I look directly at the flame and actually cannot see how far into the that the thermopile is inserted. If I replace it, I was planning to just disconnect the existing device at the wire nuts, leave it in place and then connect the new device to the wire nuts and somehow clamp it in away that it sits in the flame. Does anyone have a weblink where I can order 500mv thermopile? A brand and model number would be helpful too. Thanks in advance, VC


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## vcheez (Jul 12, 2010)

I stopped by the local heating whole sale supplier and picked up the thermopile shown below. It says it will put out 750mv. They guy at the store mentioned that there is a smaller 250mv model that some of the older furnaces used. Mine is an older furnace. I'm just a concerned that that if the coil on the gas valve needs 250mv to open and I energize it with 750mv it could be damaged? What do you guys think? Also, how do I install this thermopile, I cannot figure out where it needs to be installed. Any help will be appreciated. Thanks in advance, VC

[URL=http://s225.photobucket.com/user/videocheez/media/plumbing%20repairs/old%20furnace/IMG_7646_zpsdad48ce3.jpg.html]

[/URL]http://s225.photobucket.com/user/vi...<br /> furnace/IMG_6845_zps40e978f6.jpg.html


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## beenthere (Oct 11, 2008)

Follow the cable of the existing one. You'll see where and how its installed. Your gas valve will be marked most likely. A 750mV powerpile doesn't generate 750 mV under load. Not ure I have ever seen a furnace that used a 250mV, maybe a stove.


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## vcheez (Jul 12, 2010)

beenthere said:


> Follow the cable of the existing one. You'll see where and how its installed. Your gas valve will be marked most likely. A 750mV powerpile doesn't generate 750 mV under load. Not ure I have ever seen a furnace that used a 250mV, maybe a stove.


Yes. I took a look and think I can figure out how to make it happen. I suppose that I should turn off all gas to the furnace while making the swap. Do you think it would be fine to just close the pilot light valve?

Thanks in advance, VC


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## beenthere (Oct 11, 2008)

Yeah, just need to shut that one off.


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## vcheez (Jul 12, 2010)

beenthere said:


> Yeah, just need to shut that one off.


Thanks for the advice. The replacement thermopile did the trick for now. I did however have to retro-fit the re-installation. The new thermopile that I purchased looked nothing at all like the older unit. I bet the older thermopile is the original. It's probably 50 years old. I've posted some photos below just in case somebody else encounters a similar situation.

Thx, VC

*Old Thermopile After I Removed it*



*Old Thermopile (view where pilot light gas comes from)*

*
Pilot Light Nozzle*




*New Thermopile with Old Pilot Light Nozzle*


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