# Heil furnace inducer vibrating, capcitor handling question



## diggerdave (Feb 10, 2009)

We have a Heil natural gas furnace about 18 years old (Model #NUGK075DG07 - 867.769426). The exhauset inducer was replaced about 10 years ago. I had the natural gas shut off to the whole house Saturday while I replaced my water heater, re-routed it's gas line and added a gas shut-off valve. The furnace ran fine when I turned the gas back on. But Sunday morning I noticed the inducer was vibrating and rumbling through the duct work. 

I checked the exhaust vent line - no clogs, but I did wipe up some moisture/water build up at the inducer body exhaust port. It seems a little bit quieter today. I'm beginning to think a lot of condensation built up in the inducer while the furnace was shut down (I'm in Wisconsin). I'll open it up and clean it out to see if that helps. There are two brown wires leading from the inducer motor to an oval capacitor (picture).... I would think I need to discharge the capacitor before I handle it or open the inducer to clean it out?
Will disconnecting power at the breaker box discharge the capacitor and how long does it take?


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## yuri (Nov 29, 2008)

Put on some leather work gloves, loosen the screw on the capacitor clamp and slide it out and then put it in a thick ziploc bag with the wires attached temporary and you are safe. I would first run it for a few more days. Those ventors can safely sling some water out and it may clear up on its own. When you disturb/break the mounting gaskets/coupling you may end up with an even bigger problem and that unit is EXPENSIVE.


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## Yoyizit (Jul 11, 2008)

diggerdave said:


> the inducer was vibrating and rumbling through the duct work.


One of the impeller blade balancing clips has fallen off?

Grainger's capacitor discharge resistor is 15k, 2W. With a 100uF capacitor it would take ~2 seconds to lose 99% of its original voltage (it never goes totally to zero).


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## hvaclover (Oct 2, 2008)

Yoyizit said:


> *One of the impeller blade balancing clips has fallen off?*
> 
> Grainger's capacitor discharge resistor is 15k, 2W. With a 100uF capacitor it would take ~2 seconds to lose 99% of its original voltage (it never goes totally to zero).


Nailed that one Yowzit. Probably gonna need a new one.

But I discharge caps on my tongue, no kidding, but that is just me and i don't recommend it to any one else. 

Guess that accounts for my *electrifying* personality:whistling2::jester:


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## Yoyizit (Jul 11, 2008)

hvaclover said:


> .
> 
> Guess that accounts for my *electrifying* personality:whistling2::jester:


Yowsa, yowsa. . .:thumbsup:


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## diggerdave (Feb 10, 2009)

The inducer didn't get much better over the week, so I'd like to open it up and take a look at the impeller balancing clips. If I remove the housing body clips on the outside, will I be able to split this in half without cutting along the seam or doing a lot of prying, and possibly break the housing?


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## hvaclover (Oct 2, 2008)

nope.


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## yuri (Nov 29, 2008)

Even if you could look at the impeller you cannot put those clips on, so you need a new unit anyway. I have had to replace a few of those furnaces as some of them the burners are rotting away/flames coming out the sides and the burners are obsolete. May be a $$ pit in the future.


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## Yoyizit (Jul 11, 2008)

yuri said:


> Even if you could look at the impeller you cannot put those clips on, so you need a new unit anyway. I have had to replace a few of those furnaces as some of them the burners are rotting away/flames coming out the sides and the burners are obsolete. May be a $$ pit in the future.


Speakina' "money pits", you might want to Google your furnace along with 
"class action" or 
"recall" or 
"technical service bulletin" along with your part name.

Probably the price of a new balanced impeller is half the cost of a whole new unit. This pricing strategy may annoy you but it is designed to put you on the Repair/Replace Fence, and it usually works.

And, 
all I needed was a starter solenoid and I knew this to a high level of certainty.
A solenoid with starter motor was $70. 
I think they wanted $50 for just the solenoid.
I guess I wasn't so certain after all, so I paid the $70.
http://www.made-in-china.com/image/2f0j00KCktURPMaGoqM/Starter-Motor-Ford-.jpg
The solenoid is the little guy on top.

I'm sure MBAs have a name for this-it's not Slippery Slope. It doesn't seem to be supply and demand either. It might be the cost of inventorying smaller assemblies vs. larger assemblies that forces them to do this.

BTW, you might be able to repair the blower housing with fiberglass mesh and that gooey stuff that goes with it.


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## yuri (Nov 29, 2008)

The impeller is heat expanded/pressed formed device onto the motor shaft as a normal set screw would corrode/fall off. If you break the housing, moisture and fumes will leak out. It is glued together with high grade silicone plus those clips.


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## Yoyizit (Jul 11, 2008)

yuri said:


> The impeller is heat expanded/pressed formed device onto the motor shaft as a normal set screw would corrode/fall off. If you break the housing, moisture and fumes will leak out. It is glued together with high grade silicone plus those clips.


I'm losing hope, here. . .

OK, I'm forced to use my secret weapon.

If the blower costs 100 pieces of silver (or pesos, or yen, or Euros), and a service call costs 200 pieces of silver and the tech decides that a new blower (110 pieces of silver is your price, he had to fetch the part) will fix the problem, then you should do the DIY if the likelihood that it is only the blower is at least
100/(110+200) = ~32%.
From what I'm hearing, the likelihood is almost 100% and there is no root cause outside of the blower that caused the blower to fail. 

Looks like a DIY replacement is the rational decision of an informed HO.


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## yuri (Nov 29, 2008)

Disco was popular when I graduated high school and I had a shaggin wagon so don't ask me to resurrect my Maths courses. I haven't a clue what silver is worth. LOL:laughing:


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## hvaclover (Oct 2, 2008)

yuri said:


> Disco was popular when I graduated high school and I had a shaggin wagon so don't ask me to resurrect my Maths courses. I haven't a clue what silver is worth. LOL:laughing:


I bet my 1960s VW "Lonely Love Wagon " bus beat your shaggin wagon all to heck:thumbup:


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## yuri (Nov 29, 2008)

I wasn't "lonely" in my Chevy Van. :devil2:


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## hvaclover (Oct 2, 2008)

Neither was I. i was in the army in Germany and had that name scrawled on each side of the van.

Guys laughed at it. Chicks wanted to find out why this poor American soldier

was all alone.



GERMAN CHICKS ROCK!!:thumbup:


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## kenmac (Feb 26, 2009)

hvaclover said:


> But I discharge caps on my tongue,


 

I thought I was the only one... Been doing it for years:thumbup:


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## hvaclover (Oct 2, 2008)

Drives the ladies crazy.


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## diggerdave (Feb 10, 2009)

You guys crack me up!  I'm going to replace the inducer provided I don't have bigger problems with my burners cycling every 1:20. Being discussed in another thread....


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## hvaclover (Oct 2, 2008)

diggerdave said:


> You guys crack me up!  I'm going to replace the inducer provided I don't have bigger problems with my burners cycling every 1:20. Being discussed in another thread....


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## handyman78 (Dec 29, 2007)

Digger- I have that exact model - I installed the system in 1990 only mine has the Sears Kenmore brand- It is Heil_Quaker manufacture. I have replaced the exhaust blower since then- When the first one bombed I took it apart to see the impeller blade scraping the inside of the ABS case causing it to melt in places (it is a high speed fan) which off-balanced the fan and made quite a racket in vibration. That capacitor was easily discharged in a few minutes after killing the power and shorting with a screwdriver.


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## Yoyizit (Jul 11, 2008)

hvaclover said:


>


Nope; don't know her. . .
Mr. Lover, where are you goin' with this. . .??


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## hvaclover (Oct 2, 2008)

Call me Clover.

Let you mind take you where it may.


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## diggerdave (Feb 10, 2009)

handyman78 said:


> Digger- I have that exact model - I installed the system in 1990 only mine has the Sears Kenmore brand- It is Heil_Quaker manufacture. I have replaced the exhaust blower since then- When the first one bombed I took it apart to see the impeller blade scraping the inside of the ABS case causing it to melt in places (it is a high speed fan) which off-balanced the fan and made quite a racket in vibration. That capacitor was easily discharged in a few minutes after killing the power and shorting with a screwdriver.


Yeah that's what happened to my original unit. The metal blades rusted and scraped the sides of the housing. This one was the replacement to it (plastic blades) and something isn't right about it now... bearing or unbalanced blades i'm sure. It makes more of a muffled vibrating sound instead of a scraping sound. I can feel it when I hold on to it.

My other problem:
Can this cause my burners to short cycle... 1:20 on, 1:00 off, 1:20 on... consistantly over 20 minutes, all the while the blower is running and the stat says "system on". Also the supply temp is 140 on, 160 off, 140 on.... hitting the high limits all the time - but why? Make comments at the other thread http://www.diychatroom.com/f17/short-off-cycle-times-burner-inducer-38735/


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## kenmac (Feb 26, 2009)

A bad motor for exhaust can cause short cycling, Also, not enough air flow, cracked heat exchanger, over fired , etc, etc, If I remember correctly. This furnace is 18 yrs old ??? I would suggest you call a HVAC contractor to check it out


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## diggerdave (Feb 10, 2009)

kenmac said:


> A bad motor for exhaust can cause short cycling, Also, not enough air flow, cracked heat exchanger, over fired , etc, etc, If I remember correctly. This furnace is 18 yrs old ??? I would suggest you call a HVAC contractor to check it out


"If you remember correctly". Do you know or don't you? Don't get me started. 

What ever happened to following through on the basic troubleshooting steps before calling in the calvary. Sure I could call a contractor if I had the money. It's the easiest way out.

This motor is running very well except for the small vibration, I suspect the bearing is starting to go. It's not stalling, the blades aren't rubbing on the plastic shell and it's pulling exhaust out of the exchanger at normal speed. I'd like to understand how my blower symtoms can cause the short cycle. If it was worse I could see it. Again that's where I'm willing to learn something...

Before I replace the blower or call a tech I want to eliminate as many possibilities as I can. That's what this board is about. Yuri and beenthere had some good air flow suggetions to look into. I'll do that tomorrow. If it comes down to it I'll replace the vent blower myself - I can't afford the markup and labor right now. Nor can I afford to replace it without eliminating the other possibilities first - that I can check out. I don't want to replace the blower and find out it wasn't the problem, or that it was a simple solution that I could have done myself. I like to be diliget and take it a step at a time.


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## kenmac (Feb 26, 2009)

diggerdave said:


> "If you remember correctly". Do you know or don't you? Don't get me started.


 
Ok, I won't get you started.... I'am through:wink:


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## handyman78 (Dec 29, 2007)

Regarding the fan blade- mine is plastic as I think they all were due to the caustic nature of the exhaust condensate. Fast plastic spinning next to a plastic shell doesnt take long after a touch or 2 together to melt off some plastic- then you have the off-balanced wheel causing a rumble. Regarding the cycling, look towards the electronic fan speed/limit control. Mine went bad and I replaced it with an exact replacement however- I had to tweak it many rounds until I got it so the cycling was just right. It was hard to establish how well the small dials worked.


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## hvaclover (Oct 2, 2008)

diggerdave said:


> "*If you remember correctly". Do you know or don't you? Don't get me started. *
> 
> 
> 
> ...


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## Yoyizit (Jul 11, 2008)

hvaclover said:


> diggerdave said:
> 
> 
> > "*If you remember correctly". Do you know or don't you? Don't get me started. *
> ...


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## diggerdave (Feb 10, 2009)

hvaclover said:


> diggerdave said:
> 
> 
> > "*If you remember correctly". Do you know or don't you? Don't get me started. *
> ...


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## beenthere (Oct 11, 2008)

Depends how many parts you change that aren't bad.
As to weather or not, your saving any money by not having a tech come out.


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## Yoyizit (Jul 11, 2008)

diggerdave said:


> hvaclover said:
> 
> 
> > Absolutely, I agree with you 100%. It's the last thing I want to do and I can garuntee you I appreciate the pros help more than anyone else on this board. Really, I am greatful for everyone's help!!!!! Thank you again everyone!!!! :yes:
> ...


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## kenmac (Feb 26, 2009)

Yoyizit said:


> diggerdave said:
> 
> 
> > Some people do bite the newbies, and not just the newbies. That's a moderator's problem.
> ...


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## hvaclover (Oct 2, 2008)

kenmac said:


> Yoyizit said:
> 
> 
> > If that's an apology....accpted
> ...


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## kenmac (Feb 26, 2009)

What I need to do is stop posting on this black berry or, read b-4 I sumit. This new bb is hard to operate..or could b the operator. I have yet to figure out how to post one of the smilies


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## diggerdave (Feb 10, 2009)

Yoyizit said:


> Some people do bite the newbies, and not just the newbies. That's a moderator's problem.
> 
> For the people who reflexively say "Call somebody" I say "What is your purpose on this forum?





kenmac said:


> If that's an apology....accpted
> 
> I'll say this, sometimes you can have multiple problems that can be hard to figure out on a fourm.also, if you have a cracked heat exchanger. It can be fatal !! I'am sure no one here wants to hear of anyone getting hurt..I'll give another suggestion. Jump out your vaccum switch & see if the unit stays on.


Somehow I got taged with Yoyizit's quote there. Wierd, but anyway, I did apologize. Yeah I know it can be difficult to troubleshoot online rather than being in front of the problem. I do that a lot too. I am aware how dangerous a cracked heat exchanger can be. We have not had any sysmptoms, and I believe this cycling problem may have been going on longer than I was aware of. I have new CO2 detecters, a few months old, in the house as well. Not as accurate as the gas co, but they should let us konw if we reach unsafe levels.

Ok, I'm affaid to ask,,,,,  Just trying to lighten the mood... I have a "air proving switch" with a vacume line down to the combustion air blower. I'm sure that's what you're talking about, right? To "jump out", do you want me to disconnect the air proving switch electrical leads and jump them, or disconnect the the vacume line? Also do I jump before the furnace starts up? Picture below

Also I noticed the fan limit switch settings look like they're set to 95, 130, 175 degrees. (The max designed output on the sevice tag says 165) I was cycling at 130-140 and 150-158. Look fishy to you - like you said the swich can start to cycle at lower temps? Picture below
THANK YOU


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## diggerdave (Feb 10, 2009)

Would anyone object to moving the last post by kenmac and my reply to my other thread, http://www.diychatroom.com/f17/short-off-cycle-times-burner-inducer-38735/ ? There are more posts there dealing with the cycling isssue. Sorry I didn't think they were related when I started them....


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## hvaclover (Oct 2, 2008)

That limit looks awful yellow...Back draft or roll out?


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## kenmac (Feb 26, 2009)

hvaclover said:


> That limit looks awful yellow...Back draft or roll out?


 
I have seen some of the older ones that color


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## kenmac (Feb 26, 2009)

Diggerdave, when the unit is on & you are watching that limit. Does the limit rotate all the way around ( to the 195 or 200 mark) & turn the burners off while the blower & vent motor remain on ?? I had a ruud do this once.Replaced the limit. Same results. Air flow was fine. I had to adjust that limit a little off that 200 mark & all was fine after that .These things work with a coil type spring so, over time I,am sure thet get out of adjustment.. The vaccum switch is the silver part which you won't need to jump out if the above is happening


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## diggerdave (Feb 10, 2009)

kenmac said:


> Diggerdave, when the unit is on & you are watching that limit. Does the limit rotate all the way around ( to the 195 or 200 mark) & turn the burners off while the blower & vent motor remain on ?? I had a ruud do this once.Replaced the limit. Same results. Air flow was fine. I had to adjust that limit a little off that 200 mark & all was fine after that .These things work with a coil type spring so, over time I,am sure thet get out of adjustment.. The vaccum switch is the silver part which you won't need to jump out if the above is happening


No it actually gets to about 160 then jumps to 185 and shuts the burners and vent blower off. Main blower still running. Here is a short video up on youtube http://www.youtube.com/watch?v=-D969TvkjPw

Fan Limit Switch Dial Settings:
90 Everything off
90 Vent blower starts, valve opens, burners fire within 1-2 seconds, dial starts to turn CW
135-140 Main blower starts
<begin repeat - 6 or 7 times>
160 Dial jumps from 160 to 185, shuts burners AND vent blower off, main blower continues to run
As the exchanger cools the dial begins to turn CCW
145-150 Vent blower starts, valve opens, burners fire within 1-2 seconds, dial starts to turn CW
<end repeat>
95-100 Main blower shuts off

Do you want me to jump the vacuum switch then? Jump the wire leads together correct while the furnace is on?
Thanks


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## diggerdave (Feb 10, 2009)

hvaclover said:


> That limit looks awful yellow...Back draft or roll out?


Woops, I misspoke before when I said the flame flash was comming out of the burner tubes in front where you adjust the air fuel mix.... actually 1-2 seconds after the valve opens the burners startup and that's when I get a little bit of flame comming out of the exchanger under the burner cover/shield.I think it's a rollout at startup. Heres a video up on youtube - I'm not sure if this is ok http://www.youtube.com/watch?v=rWqGlRD2hWY

Thanks


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## hvaclover (Oct 2, 2008)

No. That furnace might have a hole in the exchanger.


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## yuri (Nov 29, 2008)

Remove the "Thanks" from the link and it will work. Looks dangerous to me. Should not be flashing back like that. The burner may be overfired and that is causing all the problems. Need to get a tech in with a manometer and some experience to check it. Try your local gas utility, maybe they will do a free pressure test. If it gets worse you may have a small explosion and burnt wiring etc. At this point in time I would not compromise your families safety by trying to DIY. Gas valves DO NOT go out of calibration/need adjusting for no reason. YOU have to live in that house and not some anonymous internet DIYers.


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## diggerdave (Feb 10, 2009)

Ok I'll have it checked.


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## kenmac (Feb 26, 2009)

hvaclover said:


> No. That furnace might have a hole in the exchanger.


 
I agree . It shouldn't be doing that.. Also could mean Burners and or cross-overs need cleaning...

I think your burners & draft motor are cycling on the limit... Providing the chamber isn"t cracked.... When the limit rolled around and made that jump. I think it was tripping the limit...Which could mean cracked chamber, not enough air flow, bad limit...


Good luck


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