# Indoor Boiler Question



## AndrewF (Dec 29, 2008)

I picked up a 114,000 btu oil boiler tonight.

It did not come with an expansion tank, and I know it needs one.

I've been reading online about sizing and other requirements of a boiler system and decided to start a thread here about it.

The plan is to install a 19" x 20" heat exchanger in my return plenum and create a single loop to the boiler.

The boiler holds 13 gallons and has a circulator pump (i have to confirm the GPM on it). The boiler has a 1 1/2" in/out pipe size from the old setup it has.

Any boiler expert here willing to chime in with any wisdom?

Note: The plan is to use the boiler as the primary heat source when the temperature is below ~20 degrees, as my 5T heat pump cant keep up and the 20kw electric resistance heat kicks in. My thermostat has an outdoor probe and can be configured to select whichever heat source I choose.

This past month, my electric bill is around $400, and we've burned about 1 cord of wood too.


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## beenthere (Oct 11, 2008)

The air handlers blower motor is not designed to take heat.
And you would have to shut off teh heat pump when the boiler is heating the house.
So you wouldn't be saving as much as you could if the heat pump was running with the boiler as aux heat.

How about putting a hydro coil in each supply trunk line. Then you can run both the heat pump and boiler at th same time.

Have a fair amount of systems out with a hydro coil as the aux heat. people like the savings of both running at the same time.


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## AndrewF (Dec 29, 2008)

I could purchase two heat exchangers and put them in the supply side, I'd have to redesign my plumbing plan as I was wanting to use only one circulation pump and would only have to plumb about 5' of line.

A couple of the heat exchangers I looked at, didnt have a huge drop of water temp at 1500 CFM, so I guess I could just loop them together....making the hot water go to the side that has the most vents first, and then catch the second side second.

Yes, I was planning on shutting the HP down whenever the boiler was running, as it would be pointless to use the hotter return air to heat up the A coil from the heat pump...and transfer "heat" back outside.

Hmmh, I am not seeing heat exchangers in the 10" x 24" size....

So if I did put it in the return side, the hot air would shorten the life of the blower motor...but by how much? I can get a replacement motor at wholesale cost...whenever it goes bad.


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## beenthere (Oct 11, 2008)

Depends on the current motors temp rating. Some are only rated for 104°F(40°C) ambient temp. 
Might want to keep 1 or 2 instock.

Doesn't have to be piped in series. Can be piped parallel and still only use one circ.


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## AndrewF (Dec 29, 2008)

Thank you, I'll check its rating and see what the cost would be for two heat exchangers.

I still need to do the pressure checks since I put the turning vanes in...maybe this weekend.

I got such a good deal on this boiler, I couldnt pass it up.


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## beenthere (Oct 11, 2008)

Check into the cost of the cost of the tank, and oil in your area.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Check into the cost of the cost of the tank, and oil in your area.


The pressure tank is around $30.
Oil is around $2.05/gallon.

I already have an underground fuel oil tank and supply lines from it to the basement that went to the old fuel oil furnace I took out.

I still have the chimney too.

If my math is correct, the boiler will be cheaper.

I have 20kw backup heat. 
I pay .105 per kilowatt hour. 
20kw of electric heat generates about 60k btu/hr.
1 gallon of diesel generates 140k btu/hr. If my boiler is 80% efficient, I'll get around 112k btu/hr.

So, for the same amount of heat, it will be about 50% cheaper with the boiler.


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## beenthere (Oct 11, 2008)

Not bad.

Got it installed yet? :laughing:

Did you get those static pressure checks done yet?


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## meboatermike (Oct 29, 2009)

Wow, here in Southern Maine the cash price is currently 2.549 and it goes up from there, way up as you head north.

Has your underground oil tank been tested to make sure it is in good shape? Around here undergrounds are supposed to be registered etc. with the state  lots of leakage problems across the state over the years.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Not bad.
> 
> Got it installed yet? :laughing:
> 
> Did you get those static pressure checks done yet?


I am trying, working late doesnt help me get things done.

It is supposed to get down in the single digits tomorrow night....unfortunately, it wont be installed by then. 

BTW, a buddy of mine works for AOSmith. He checked the motor of my air/handler, said it is rated at 131 degrees, which is at constant duty rating. Its LRC is rated much higher.

He suggested I run the boiler water temp around 150...which depending on the heat exchanger I buy, might result in an ambient air temperature around 130.


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## beenthere (Oct 11, 2008)

then you won't be able to use the heat pump when the boiler is running. And will 150° water be enough to heat your house.

Depends on air flow, as far as what temp the air will be from the hydro coils.

Much cheaper heating if the heat pump and boiler are both running.


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## AndrewF (Dec 29, 2008)

meboatermike said:


> Wow, here in Southern Maine the cash price is currently 2.549 and it goes up from there, way up as you head north.
> 
> Has your underground oil tank been tested to make sure it is in good shape? Around here undergrounds are supposed to be registered etc. with the state  lots of leakage problems across the state over the years.


Road DIesel is around $2.75/gallon here. Offroad is usually 60-70 less a gallon.

I havent checked it sine I moved in. I was going to tear it out this summer, but I may not not. I may still use the backhoe to dig near it and inspect and see if it has any rusting or leakage.


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## AndrewF (Dec 29, 2008)

beenthere said:


> then you won't be able to use the heat pump when the boiler is running. And will 150° water be enough to heat your house.
> 
> Depends on air flow, as far as what temp the air will be from the hydro coils.
> 
> Much cheaper heating if the heat pump and boiler are both running.


Yes, I understand.

The hottest I have ever seen my A coil get, is around 118. So, if I my boiler heat exchanger is running at 150+, it will be hotter than my A coil ever has been.

My plan was to only run the boiler at a specific outdoor temperature that is the tipping point of lack of efficiency of the HP. My HP and A/H pull around 20 amps when running....which is about 63 cents an hour.


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## beenthere (Oct 11, 2008)

If your heat pump and air handler combined are drawing 20 amps.
Then at 240 volts. that 4800 watts. At a COP of 2.2(15 to 19° outdoor temp), that gives you 112,000 BTUs for $1.957

With oil at $2.05 a gallon, and 80% efficiency. Plus 1KW for the air handlers blower. You get 112,000 BTUs for $2.155

While in the example, the savings of the heat pump is small. Your strips are coming on before 20° outdoor temp. So the heat pumps COP will be higher. And will give you even more heat for even less money.

The hydro coils in the return will cost you more in fuel every year. then what little work, and cost the 2 coils in the supply will be.

Save a dollar now, spend 20 later.


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## AndrewF (Dec 29, 2008)

but can I find a heat exchanger to fit in a 10x24 trunk?

So far, not without having a custom one built. 

Assuming oil and electric stayed at the current rates (we know they wont), based on those numbers, it'll take 2500 hrs of run time to make up the cost of one heat exchanger, which is I think about 6 years.

I like your idea, and if I can make it work, I'll go that route. I am going to stop at the local supply house tomorrow and see what heat exchangers they have available locally.

Online, there are a number of vendors, but none that sell any that will fit in a 10x24 trunk. My drop down box is 20x25, so I have plenty of room there. My crossover box under the unit, is 16x30...so ample room there too.


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## beenthere (Oct 11, 2008)

Why must it fit in a 10X24 duct?


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## AndrewF (Dec 29, 2008)

What if I put the heat exchanger between the AH and the supply trunk? There isnt much room there, but would that be an ok spot?

I still have my turning vanes above it....it would put it within about 2" of the resistant heat coil packs.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Why must it fit in a 10X24 duct?


Because you indicated it should be after the HP A coil in the air handler....

The A coil is on the bottom of the unit and the fan above it, and above the fan, the 20kw electric heat.

As you can see in the above photo, my supply trunk which goes left and right, is 10" x 24"

THis is an upflow setup. Air comes in from the bottom and exits out the top.


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## beenthere (Oct 11, 2008)

You get the coil made to fit your duct work.
The coil can be bigger then the duct, was my point.
because the ends of the coil would restrict air flow if inside the duct.


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## AndrewF (Dec 29, 2008)

I understand.

THank you.


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## beenthere (Oct 11, 2008)

Almost forget.
York makes a hydro coil that sits on top of the air handler. Just don't know if you have enough room.


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## AndrewF (Dec 29, 2008)

Any idea how close the heat exchanger coil could be to my 20kw e-heat?

http://www.houseneeds.com/shop/Heat...exchangers/airhandlers/heatingcoilerstech.asp

The E-heat will basically be "disconnected" because the boiler is taking its place. I might even take it out and put it back in the box to help with my static pressure....but if I didnt, I'd wire it to W3 on my t-stat and configure the t-stat to never use it unless I manually energize it.


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## beenthere (Oct 11, 2008)

20 KW of strip is 68,260 BTUs.

As you see, hydro coils are very restrictive to air flow.

Take the 18X18C3.5 coil. At 1500 CFM, it has a .24”wc PD.
If you were to use that coil with only 1000CFM of air flow going through it. Its PD would only be .105"wc.

Hydro coils need to be selected for both the BTU you need, and the PD your system can overcome.

And often. A large BTU coil is preferable to use at a lower PD. Then a smaller higher rated PD one rated for the lower BTU you need.


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## AndrewF (Dec 29, 2008)

You lost me there.

If I was willing to live with putting a larger hydro coil in front of the A Coil in the 20x25 drop down box, that would be better to my airflow and WC then a smaller 12x12 on the supply side, right?

Also, the air output on the AH is about a 12x12 opening....because of the way it was made with the heat coil slot...you can see one off the panel that limit the width to 12" instead of the full width of the AH (23")

I could put a 12x20 coil in the blue area of the first photo pretty easily.


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## beenthere (Oct 11, 2008)

I was refering to using 2 coils on the supply side. One for each supply trunk.

For a single coil. You would need the 22X25X3.5, rated at 2700 CFM and a PD of .32"wc.
Because when the air flow is only 2000CFM through it. Its PD would only be .18"wc.

If your air flow is less then 2000CFM through it. Its PD will be even lower.
But. As the air flow drops, the air temp coing from it will increase. And your back to harming your blower motor.

Next. What about refrigerant migration. With the coil heating up the air that is being blown over the coil. You will cause liquid refrigerant migration. And could cause oil problems with your heat pump.

Putting a hydro coil before the indoor coil is a real bad idea. Could cost you more in repairs then you save on your heating bill.

Put the larger coil on top of your air handler. And slant the transition as much as you can.

Or use 2 coils as I suggested earlier. And you'll get better air flow.

Before the coil can be put in. You still need to get your Static pressure down lower. Or you'll end up not being able to use the heat pump for heating or cooling no matter what the outdoor temp is.


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## AndrewF (Dec 29, 2008)

Would frigerant migration be less of a concern if my HP has a crankcase heater?

The manufacture PDF says : 
Crankcase heater (where indicated)​

Why dont I hear concern with oil migration on a standard A/C system that is after say a fuel oil or LP furnace? Does it have anything to do with the reversing valve?


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## AndrewF (Dec 29, 2008)

I did find a manufacture that sells 12" x 24" unit and is rated at 124,000 BTU.

Wouldnt that restrict my airflow on each side of the supply trunk at an angle too much?


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## beenthere (Oct 11, 2008)

Because an A/C doesn't run in the winter.
It gets restarted in the spring on a warm day. A heat pump will be required to run again on a cold day.
Crack case heater will help keep oil and refrigerant from being mixed in the crank case. But not in the outdoor coil.

Whats the PD of the 12X24 coil you found.

2 large coils one in/at each supply trunk will have less then 1 big coil with all the air going through it.

The 18X18's i posted about. Would only add.105" PD.

Will the 12X24 you found add less?


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## Marty S. (Oct 31, 2009)

Adding boiler coils is out of my league but why not increase the supply duct size to fit the larger coils then back down to trunk size instead of dinking around with slanting it?


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## beenthere (Oct 11, 2008)

He doesn't have a lot of room between his air handler and the trunk line.
Already has an air flow problem. 

The hydro coil will compound his air flow problem.


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## tk03 (Sep 30, 2008)

I am not much of a duct guy so I may be wrong but I thought it was best to pull through a coil. I thought when you pushed a coil most of the air goes through the center portion of the coil and when you pulled through you pull air through the entire surface. Is that not why air handlers started pulling through the coil as opposed to pushing the air through as they used to many years ago.


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## beenthere (Oct 11, 2008)

No.
Air handlers. Were pretty much always pull through.

Electric furnaces were, and still are push through(yeah, thats were it gets dumb, an air handler is often an electric furnace, but still configured as an air handler).
Electric furnaces came out before air handlers. Since A/C wasn't a common thing in houses 40 years go. And had no provisions for a coil to be placed in it.

You can take a modular coil. that can be used with either a modular blower/air handler, or a furnace.
And its capacity will increase with one furnace and decrease with another, and remain the same with yet another furnace.

So its position in the air stream doesn't really change its capacity.
Since in all configurations, it has coil bypass(obviously not all the air going through the coil touches the fins or tubes).

The distance between coil and blower, weather push or pull through. Will have more effect on the air flow pattern through the coil.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Whats the PD of the 12X24 coil you found.
> 
> Will the 12X24 you found add less?


They didnt list the info online, I'll call them tomorrow and find out what the specs on it are.



beenthere said:


> He doesn't have a lot of room between his air handler and the trunk line.
> Already has an air flow problem.
> 
> The hydro coil will compound his air flow problem.


Correct, I don't have the room and I already upgraded all my trunks from 8x24 to 10x24. If I was to make the trunk any bigger, I'd have to redo my return dropdown box and the box the AH sits on....I am not about to spend the money to do that again.


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## beenthere (Oct 11, 2008)

So what is the current static pressure at what CFM???


Oh. And incase I forgot to ask earlier.


What is the current static pressure at what CFM???


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## AndrewF (Dec 29, 2008)

I stopped at Home Depot to price out the plumbing supplies I needed, $210. *gulp*

I'll check a real supply house tomorrow.

Can I use PEX instead of copper?

---------

PEX tubing can be used up to 200° Fahrenheit for heating applications. For plumbing, PEX is limited to 180° F. Temperature limitations are always noted on the print line of the PEX tubing. Recommended 140 max for safety and conservation.


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## beenthere (Oct 11, 2008)

Hpex is fine. 
With that boiler, you MUST use Hpex. If you use a pex without an oxygen barrier. You will have a internally rusted up boiler. that clogs your water lines.


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## AndrewF (Dec 29, 2008)

If the numbers on the 12x24 exchangers are acceptable, could I make an A with them and stick them like this? (The brown in this image)

Then I wouldnt need turning vanes up there anymore, right?

The downside is that I need more airflow to the left than the right....the line to the left has more supply takeoffs than the one to the right.

My plan with the turning vanes was to shift them as I needed to force more airflow one direction or the other.


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## Marty S. (Oct 31, 2009)

I meant put an increaser on each side of the trunk, then coils, then decrease back to the 10x24. Only would require removing one section of supply duct on each side of the air handler and not change the return or platform at all.


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## beenthere (Oct 11, 2008)

Afraid installing them in an A like that. Will decrease air flow.

The air would be directed at a 45° angle toward the top of the trunk line.

Marty has the right idea.


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## AndrewF (Dec 29, 2008)

beenthere said:


> So what is the current static pressure at what CFM???


I haven't forgotten to check. Its on my todo list tonight.

I did an audit of all the return vents in the house and finished adding one to the "guest" room, which had zero.

2nd floor, approx 1400 sq ft, 9 supply ducts via 6" round pipe.

Returns:
Bedroom #1: 14" x 5.5" - interior 2x4 wall
Bedroom #2: 14" x 5.5" - interior 2x4 wall
Bedroom #3: 14" x 5.5" - interior 2x4 wall


1st floor, approx 1,800 sq ft, 14 supply ducts via 6" round pipe

Returns:
Family: 21" x 6" - interior 2x6 wall
Dinning: 30" x 6" - interior 2x4 wall
Toy: 14" x 5.5" - interior 2x4 wall
Guest: 6" x 6" - interior 2x6 wall (cavity is 6" wide)
Hall: 14" x 5.5" - interior 2x4 wall, across from tstat
Office: None, on slab, no way to add
Kitchen: none, will be adding one to a 2x6 wall cavity.

Basement: 1500 sq ft (unfinished)
4 supplies via 6" pipe each from supply trunk, no return.

I dont think I have adequate return vents which is attributing to my high static pressure on the return side.

The basement really needs to be heated because most of the 1st floor is either tile or wood flooring, and its cold to walk on. The basement is current 55 degrees.


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## AndrewF (Dec 29, 2008)

Marty S. said:


> I meant put an increaser on each side of the trunk, then coils, then decrease back to the 10x24. Only would require removing one section of supply duct on each side of the air handler and not change the return or platform at all.


My current duct is 10x24. So would I be going to something like 10x36, or 12x24 or even 14" x 24"?


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## beenthere (Oct 11, 2008)

Don't add a return to the kitchen. Unless it will be more then 10' from the range hood.

You don't have enough return either.

You might want to install a central return on the first floor somewhere near a hallway.
Plus add a return to the basement.


Just have a transition(2 of them) made to put the coils in.

If you give the coil submitals to a sheet metal shop. They can make them for you.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Don't add a return to the kitchen. Unless it will be more then 10' from the range hood.
> 
> You don't have enough return either.
> 
> ...


It is an open kitchen design. The return would be approximately 18' from the stove/oven and at the entrance to the hallway.

So is it safe to assume the original dutwork in the house was sized incorrectly then? As you may recall, I upsized the trunks from 8x24...and am now trying to find a creative way to add additional returns.


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## Marty S. (Oct 31, 2009)

Yep get the coils first then have the tinners make the transitions. Might want them to make a pair of flex connectors also to make assembly easy. Beenthere suggested 18x18 coils for each side earlier to keep the PD minimal.


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## Marty S. (Oct 31, 2009)

Just by count you have plenty of suppies for a 5 ton system but are lacking on returns. Add your one in the kitchen hall and two 6x30's in the basement.


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## beenthere (Oct 11, 2008)

Its a pretty safe bet. your whole duct system was sized incorrectly. And was under sized.
Including your supply branches.


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## beenthere (Oct 11, 2008)

Marty S. said:


> Just by count you have plenty of suppies for a 5 ton system but are lacking on returns. Add your one in the kitchen hall and two 6x30's in the basement.


Other then about 540CFM to the second floor. And 4 unknown size supplies to the basement.

What makes you think he has enough supply.


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## AndrewF (Dec 29, 2008)

Here is the thread from last year on the topic.

http://www.diychatroom.com/f17/hvac-airflow-issue-34616/index2/#post209164


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## AndrewF (Dec 29, 2008)

Hmmh, I cant seem to get the online forumulas to work for me.

All E-heat engergized, I pull 88.5 amps per 240 leg.
VAC: 238
1KW = 3413 BTUs

Convert Amps to Watts: 88.5 amps * 238 volts = 21,063 Watts
Convert Watts to Kw: 21063/1000 =21.06 KW
Convert KW to BTUs: 21.06KW * 3413 = 71,888 BTUs.

Is that right?

As for my WC test.

If I take out the 20x25x4" filter, There is about a pencil mark difference in the water level on my homemande manometer.

If I leave the filter in, I have approximately 1/8 - 1/4" per side, so 1/4 to 1/2" WC.

As for temperature rise (to calcuate CFM)

Input: 66
Output: 105
Temp Rise: 39
Corrected: 42.12

My CFM is around: 1706 with no air filter
and is around 1584 with the filter.

I still have 2 more turning vanes to install on the supply side, and 5 on the return.


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## beenthere (Oct 11, 2008)

Static on the supply side should be read also.
Your math is correct on BTU.

1706 CFM is still too low for a 5 ton heat pump. Weather in heat or cool mode.

Adding the hydro coil to the return would lower your air flow even more.
2 over sized coils on the supply, won't lower the air flow as much. And if you have a sheet metal shop make the fitting as a radius Tee. It will help improve/increase air flow.


From your other thread, you have 27-6" supplies. At 1706CFM total from the air handler, that would make them have an average of 63CFM.


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## AndrewF (Dec 29, 2008)

I put the remaining turning vanes in tonight and opened up another return.

71,888 BTU
Temp rise corrected: 37.8

CFM = 1901 

This is with no filter.

I dont think I can get it much better than that based on what I have to work with.

The WC measurements coming up next.


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## AndrewF (Dec 29, 2008)

I get less than 1/16" of an inch of WC change on my supply side.

On the return, I get 1/16" of an inch with no filter installed (one sie of manometer)

I get a little over 1/8 (so likely 3/16") with my 20x25x4 filter.

Return no filter 1/8" WC .125
Return with filter 1/4" WC .25

These are based on the fan speed of high.

If there is a decent tool online that will give me digital readings on this, I'll buy one if being that accurate is critical.


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## beenthere (Oct 11, 2008)

Digiatal manometers
A303 static probe kit for manometers

The last link also sells manometers. But, I don't think you'll like the price of them.

The static probes, make it easier to get a accurate reading.


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## AndrewF (Dec 29, 2008)

SO which is more accurate for a CFM reading. The temperature rise method or the WC numbers based on the manufacture chart?

If temperature rise, won't it be off some based on the fact that depending which direction of my supply plenum, results in different temperature readings? Also, if I am say, 5' from the turn, is that less accurate than being at say, 1'?


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## beenthere (Oct 11, 2008)

AndrewF said:


> I get less than 1/16" of an inch of WC change on my supply side.
> 
> On the return, I get 1/16" of an inch with no filter installed (one side of manometer)
> 
> ...


If thats 1/8 on one side, and 1/4 on one side.
Then your total static is .75" with air filter.


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## beenthere (Oct 11, 2008)

AndrewF said:


> SO which is more accurate for a CFM reading. The temperature rise method or the WC numbers based on the manufacture chart?
> 
> If temperature rise, won't it be off some based on the fact that depending which direction of my supply plenum, results in different temperature readings? Also, if I am say, 5' from the turn, is that less accurate than being at say, 1'?


If you use static probes and a digital, or inclined manometer. The wc.

What blower speed is it set for with those readings.

Since amp readings can vary with how you hold the amp probe.

But, you see that you CFM is not on the chart, with your Static pressure.

Temp reading should be 1 to 3 foot from plenum to be uneffected by radiant heat.


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## AndrewF (Dec 29, 2008)

If supply is less than 1/16th of an inch per side of manometer, and we assume it is 1/16 total, that would be .0625.

Add the .25 for the return side with filter, and then subtract the manufacture specs for the 20kw heat tape.

.0625 + .25 -.02 = .2925

I could be wrong here...hence why I might scour ebay for a cheap digital manometer.


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## beenthere (Oct 11, 2008)

See post 53 for links.

Never assume with a water tube.

If your going to get a digital manometer, and the static probes I posted links to. You be able to get much more accurate readings.

Was your return 1/4 one side. Or both sides added together.


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## AndrewF (Dec 29, 2008)

At this point, I am not sure what else I can change to tweak the system anymore than I have...so I dont think spending $70-80 is worth it.

What I might do is wait until Spring and have the system refrigerant levels checked and at the same time have them do the test.

I suspect my system might be overcharged a little.


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## beenthere (Oct 11, 2008)

You may have a hard time finding a company that knows how to check static pressure.


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## AndrewF (Dec 29, 2008)

beenthere said:


> You may have a hard time finding a company that knows how to check static pressure.


Hmmph! You mean every HVAC guy doesnt know how? 

Oh yeah, that is what got me into this HVAC DIY project in the first place....


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## AndrewF (Dec 29, 2008)

This should work too, right?

http://cgi.ebay.com/Gas-LPG-Manifol...emQQptZLH_DefaultDomain_0?hash=item5ad63e602b


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## Marty S. (Oct 31, 2009)

If your heart isn't set on digital then a magnahelix might be cheaper. Mine was $80 or so.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Hpex is fine.
> With that boiler, you MUST use Hpex. If you use a pex without an oxygen barrier. You will have a internally rusted up boiler. that clogs your water lines.


Why must I use pex with an oxygen barrier?


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## beenthere (Oct 11, 2008)

To prevent rust. Which will clog up everything.


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## AndrewF (Dec 29, 2008)

beenthere said:


> To prevent rust. Which will clog up everything.


So oxygen barrier PEX pipe keeps O2 from soaking into the water? 

I thought one just mixed in glycol or something to keep that from happening, no?


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## beenthere (Oct 11, 2008)

No. Glycol prevents freezing or pipe bursting. And also decreases heat transfer rate. In other words, raises heating or cooling bill, depending on system type.
But nothing to prevent oxygen from being drawn into the water through non oxygen barrier pex.

Water likes to absorb oxygen.


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## AndrewF (Dec 29, 2008)

THis product should work, right? 

http://www.h-a-s.com/literature/Hydro-PEX_Press_Fittings/Hydro-Flex%20PEX-AL-PEX%20Specification.pdf


Engineering Specification:
Tubing shall be a 5-layer barrier PEX tubing approved for radiant heating and potable water applications. 

*Hydro-Flex PEX-AL-PEX Multi-Layered Composite Pipe 1" x 100'*consists of an overlapped welded aluminum core with an inner of and outer layer cross linked polyethylene. The inner welded layer of aluminum makes Hydro-Flex PEX-AL-PEX 100% oxygen tight, providing longer life for heating system components.


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## beenthere (Oct 11, 2008)

Yep. that will work.


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## AndrewF (Dec 29, 2008)

So I've talked to a number of vendors who sell heat exchangers, they recommend using the 12x18 HE and blocking off the 6" that the HE wont cover.

Since I have 12 - 6" supply take offs on the right side, I think that is fine.

I am more concerned for trunk that goes left of my AH, it has 15 - 6" supply takeoffs.

Although based on this chart (see pdf), an 18x12 trunk is rated for 1100 CFM.

So maybe it is ok if I get 12x18 HE and stick in each supply trunk, they would be within 6" of the AH blower....thoughts?

Or I could get the 12x24 unit and stick it on top of the AH before it connects to my 10x24 trunks.


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## beenthere (Oct 11, 2008)

How much PD will that coil have at the air flow you need in each trunk.


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## AndrewF (Dec 29, 2008)

beenthere said:


> How much PD will that coil have at the air flow you need in each trunk.


I dont know yet, I asked the vendor for the manufacture specs on their unit that size.


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## beenthere (Oct 11, 2008)

The main idea of using those larger coils earlier was to minimize PD and get/keep your air flow up.
Next, using those 2 larger coils. You also decrease the temp your boiler water needs to be. Saves a little money on oil.


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## AndrewF (Dec 29, 2008)

The 12x24 has the same as a 16x18.

.257 at 1500 CFM and;
.274 at 1693 CFM.

My AH runs around 1700 CFM from the last heat rise test I did.

As for the 12x18, i dont have an answer on its specs yet.

A 12x12 at 1016 CFM has .195
A 12x12 at 900 CFM has .185

So the .274 single unit has a lower WC than two 12x12s do...so why not save on plumbing and HE costs and just install the 12x24 at the takeoff and remove the 20KW heat coils (iirc, they add .2 WC)


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## beenthere (Oct 11, 2008)

The 12X24 at 1693 would only have a .1"wc PD
And at 900CFM it would only have a .08"wc PD.

If you use the 16X18 and have transitions made(no dead heading/blocking open duct space, creates turbulence that increases PD).
Then you make you blower work easier.

You can remove your strip heaters either way, and make your blower work easier.
But keep them handy. In another 2 years or so. Oil will be 4 bucks plus a gallon again.

If you want to use only 1 coil, thats fine. But, mounted at the air handler, it generally takes a coil designed for that mount to keep the PD down. Custom coils are seldom made with the turbulence between the coil and air handler in mind.


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## AndrewF (Dec 29, 2008)

Thank you sir.

I am plumbing up the boiler now. I just gave it a good cleaning...no wonder the previous owner wasnt getting optimal heat output from it...the jackets were at least 80% clogged of crap.

Is there any reason the fuel oil lines cant cross the top of the exhaust pipe? I plan on moving the valve junction to the right so that a potential leak of the valve would never drip on the exhaust.

The reason I'd like to go across, is so that I can follow the beam post down to the burner and never have to worry about someome tripping on them, etc. There would be about 5" clearence from the top of the pipe to the lines.

Also, how could I figure out which line was original supply and which one was return from the buried oil tank?


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## beenthere (Oct 11, 2008)

Looks like it was pretty bad.
Code will require 18" clearance to your oil pipes. You don't want oil being heated to or above 140’F.
At 140, it produces enough vapor to maintain a flame if it was ignited. So it needs to be shielded from heat from your flue pipe.
Also. Needs to have an anti siphon valve if you run it over head and the oil level at anytime can be above the burner(lots have been installed with out one, and some have regretted it later. After a $10,000.00 plus clean up.).

You should use firematic oil valves. 

Burner housing looks slightly damaged by excess heat.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Looks like it was pretty bad.
> Code will require 18" clearance to your oil pipes. You don't want oil being heated to or above 140’F.
> At 140, it produces enough vapor to maintain a flame if it was ignited. So it needs to be shielded from heat from your flue pipe.
> Also. Needs to have an anti siphon valve if you run it over head and the oil level at anytime can be above the burner(lots have been installed with out one, and some have regretted it later. After a $10,000.00 plus clean up.).
> ...


I can re-route the lines then, I was just trying to go the better/easier route.

Is it still 18" if I use double wall (insulated) pipe?

Yes, I believe the burner did "overheat" due to being pretty much plugged up...there wasnt really any place for the exhaust to go....and since it wasnt heating up the water jacket and tank quickly, the internal thermostat kept calling for heat.

The previous owners claim they spent $4k to heat a 1400 sq ft house last winter, I brushed it off due to the house being an older house...but now I think it was due to improper maintenance of the boiler....hopefully the damage isnt severe to where the tank will rupture on me at some point.....at least the basement drain is about 2' from the boiler.

I will order anti-siphon valves, they werent here before, but I like the added protection they bring.


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## sarlaud (Jan 24, 2010)

*Expansion Tank*

As far as the expansion tank, get a diaphram type tank extrol 30 or equal. Make sure it is for heating use. The model 30 equates to a 2 1/2 gal unit. You can buy at home depot off the shelf.:thumbsup:


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## beenthere (Oct 11, 2008)

Not sure on the clearance for a double wall pipe off the top of my head(probably 12"). But, it would cost more then one of the hydro coils.

If its listed for use with type L vent. Then 9" for type L vent.


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## AndrewF (Dec 29, 2008)

sarlaud said:


> As far as the expansion tank, get a diaphram type tank extrol 30 or equal. Make sure it is for heating use. The model 30 equates to a 2 1/2 gal unit. You can buy at home depot off the shelf.:thumbsup:


Thanks, I have the one that was originally installed with this unit. The previous owners found it and provided it at no charge.


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## beenthere (Oct 11, 2008)

Check air charge before installing it.


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## sarlaud (Jan 24, 2010)

*Fuel Oil Lines*

In my state the fuel oil line needs to be the orange coated line! Its worth it to get this type line or sleeve your line with flexible plastic electrical conduit...1/2" or larger! This will keep line from kinking when you need to bend( more so with the electrical conduit! Also in the picture with your burner.... you need a new nozzle and your oil line is kinked at your flare nut... need to replace that piece. Do not use compression fittings!!! They are not to code! They must be Flared fittings!


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## sarlaud (Jan 24, 2010)

*Valves*

All your valves in the system need to be firomatic! No gate or ball valves! Those valves you show have compression fittings also.


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## AndrewF (Dec 29, 2008)

sarlaud said:


> Also in the picture with your burner.... you need a new nozzle and your oil line is kinked at your flare nut... need to replace that piece.


Yes, that is the old line...I flattened them when I unhooked them a couple of years ago.


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## AndrewF (Dec 29, 2008)

I picked the tank up, it was installed in 2006 and was used for three heating seasons.

Looks to be a nice tank as it has the auto fill valve.

http://www.plumbersurplus.com/Prod/...Expansion-Tank-4-4-Gallon-(110-1)/7938/Cat/20


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## AndrewF (Dec 29, 2008)

AndrewF said:


> Why must I use pex with an oxygen barrier?





beenthere said:


> To prevent rust. Which will clog up everything.


If my system has an auto air purging valve, and water has Oxygen in it, why is it as important to have O2 barrier PEX instead of regular pex? The valve is going to purge the 02 anyways, right?

So if the valve is going to release any air in the system, doesnt that resolve the O2 absorption issue?


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## beenthere (Oct 11, 2008)

Nope.

The air is constantly absorbed through the non oxygen barrier pex. And all your water will have a high amount of oxygen in it. You end up with micro bubbles that your air vent won't get rid of.

With oxygen barrier. Your system will "eventually" get rid of the air"micro" bubbles, if they are not constantly re-added to the water.

I know it sounds strange to you. It has too many. And those that decided it would hurt if it was not oxygen barrier. Well, they end up regretting that decision.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Nope.
> 
> The air is constantly absorbed through the non oxygen barrier pex. And all your water will have a high amount of oxygen in it. You end up with micro bubbles that your air vent won't get rid of.
> 
> ...


I did order O2 barrier PEX, but still had to ask the question again 

Thanks for the recommendation on the fireomatic valve too, I have one of those coming.


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## AndrewF (Dec 29, 2008)

The boiler is hooked up and working.

I have some tweaking to do this weekend, but am relieved to have it all working.

Its not the prettiest of installs, but it is working.

The water temp is currently around 160 degrees.
The return temp is 66 degrees
The supply to the left is 116 and the supply to the right is 107.

This is without the HP running as it is currently 12 out and I was curious what temperature rise I would see.

I need to do a new heat rise test this weekend and see what my new CFM and WD is....I imagine CFM is between 1500-1600, but that is a wild guess.


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## AndrewF (Dec 29, 2008)

The boiler cant get the water temp above 159 with the circulator running and my AH.

So I guess I am taking out more heat than the boiler can produce....if I turn the AH off, after a few minutes, the boiler catches up and finally shuts off.

I need to learn how to adjust the airflow for the pump as well. With it wide open, it seems to get hotter faster....but then it also wont start (ignite). Sometimes it ignites and there is a lot of smoke...which I think is beause it is spraying fuel in, but it is not getting ignited right away, then "pools" up, then ignites.

I have to have it about 1/2 the way closed before it will ignite....maybe I have the electrodes adjusted wrong.

I also hooked my Heat exchanger up wrong...I saw a recommendation to have the return come out the side closest to the fan....so that the air picks up the heat from the cooler water before finally picking up more heat as it leaves the coils....but I forgot to do that...I'll fix it later.


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## beenthere (Oct 11, 2008)

Setting a oil boiler up by eye ball. Doesn't get it close.

You might want to get some one in with a combustion analyzer to set it up right. So it doesn't soot or coke up.

Too much air often causes a delayed ignition. Air fuel mixture is a relatively narrow band.


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## beenthere (Oct 11, 2008)

AndrewF said:


> I also hooked my Heat exchanger up wrong...I saw a recommendation to have the return come out the side closest to the fan....so that the air picks up the heat from the cooler water before finally picking up more heat as it leaves the coils....but I forgot to do that...I'll fix it later.


That is a flip of the quarter.
Best heat exchange happens at greatest temp difference. So having the hottest water at the coldest air first gives better transfer that way also.

I would leave it that way.


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## beenthere (Oct 11, 2008)

Originally said that backwards.

If your getting a 94° temp rise through the boiler. Your not moving enough water.

Post pics of piping.


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## AndrewF (Dec 29, 2008)

beenthere said:


> That is a flip of the quarter.
> Best heat exchange happens at greatest temp difference. So having the hottest water at the coldest air first gives better transfer that way also.
> 
> I would leave it that way.


Ok, I'll leave it plumbed as I have it.



beenthere said:


> Originally said that backwards.
> 
> If your getting a 94° temp rise through the boiler. Your not moving enough water.
> 
> Post pics of piping.


The picture of the HE is one before I tee'd in a valve so I could bleed the system.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Originally said that backwards.
> 
> If your getting a 94° temp rise through the boiler. Your not moving enough water.
> 
> Post pics of piping.


I am not moving enough water or air?


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## AndrewF (Dec 29, 2008)

beenthere said:


> Setting a oil boiler up by eye ball. Doesn't get it close.
> 
> You might want to get some one in with a combustion analyzer to set it up right. So it doesn't soot or coke up.
> 
> Too much air often causes a delayed ignition. Air fuel mixture is a relatively narrow band.


I will do that once I am done tweaking the system. I haven't put the damper in the exhaust pipe yet, that is tonight's project, along with adding temperature probes and a burner monitoring relay to my home monitoring system.

I did put a new fuel filter in, but I didnt put a new nozzle on. I do have a new one. It has an 80 degree .85 GPH nozzle now. The combustion chamber is about 10" diameter, which when cross referenced with Delavan, looks correct.


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## AndrewF (Dec 29, 2008)

I should add that for now, I only bought one Heat Exchanger and installed it on top of the furnace before the supply trunk.

So I imagine my WC is out of range...


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## beenthere (Oct 11, 2008)

That old nozzle may not be letting moving enough oil.
Without a barometric damper lots of your heat is going up the chimney instead of in the water.

Single coil is probably too restrictive for that circ.

Vanes are too close together near the hydro coil.

If the boiler was working the way its suppose to. Then by temp rise calc your flow rate through the hydro coil would only be 2.5 GPM.


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## AndrewF (Dec 29, 2008)

beenthere said:


> That old nozzle may not be letting moving enough oil.
> Without a barometric damper lots of your heat is going up the chimney instead of in the water.
> 
> Single coil is probably too restrictive for that circ.
> ...


What do you mean by Single coil?

How else should I move the vanes? The total width to work with is 12" and total height is 10".

There are two in the center up top, you can barely see them in the photo.

I havent taken the heat pack out yet either.


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## beenthere (Oct 11, 2008)

1 Hydro coil.

Need 1 to 2 inches between vanes.


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## beenthere (Oct 11, 2008)

Somewhat like this.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Somewhat like this.


At least I have enough material for two more vanes. I'll add two more then.

I thought the spacing was supposed to be the same as the width of the vane...IIRC, mine are 6".


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## beenthere (Oct 11, 2008)

Doesn't work well on small duct systems.

Also why they come in smaller sizes.

I have used 6" in 8 and 10" high ducts. Just spaced 2" apart. Works fine.


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## AndrewF (Dec 29, 2008)

by the way, when I put the heat exchanger in...the air moving thru the ductwork became MUCH quieter than it was before.

I imagine it is because there is much less turbulence...and maybe less air flow.

If I can, I'll do the heat rise test tonight and re-calculate my AirFlow to c onfirm this theory.


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## beenthere (Oct 11, 2008)

AndrewF said:


> by the way, when I put the heat exchanger in...the air moving thru the ductwork became MUCH quieter than it was before.
> 
> I imagine it is because there is much less turbulence...and maybe less air flow.



Yep. Air flow has been reduced. So turbulence in your ducts is reduced.


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## AndrewF (Dec 29, 2008)

So what do you think the heat rise should be on just HE only? These numbers are with the HP on and the boiler.

HVAC Return 
68°

HVAC Supply - North 
121°

HVAC Supply - South 
130°

HVAC Suction 
96°

HVAC Liquid Line 
79°

HVAC Condenser 
9°

Outside 
15°


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## beenthere (Oct 11, 2008)

What it should be, or what it is at its current operating parameters?

Your probably getting around 40°.

You should be getting around 65° -5 +8 if the circ was moving 10 to 12 GPM and the blower is moving 1600CFM.


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## AndrewF (Dec 29, 2008)

Looks like I have some more work to do then. 

HVAC Return 
69°

HVAC Supply - North 
127°

HVAC Supply - South 
135°

HVAC Suction 
103°

HVAC Liquid Line 
81°

HVAC Condenser 
11°

Outside 
17°


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## AndrewF (Dec 29, 2008)

Based on this data from the manufacture for a similar coil that is of the same surface area, based on the way I have it installed now...as I suspected, I am about 50% of efficiency, right?

Or was this HE a badly designed one?


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## beenthere (Oct 11, 2008)

About 50%, if your moving 1600 CFM through that coil.


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## AndrewF (Dec 29, 2008)

So if I replaced the supply trunk immediately above my AH with a 5'x14x24 piece of supply, would that be a good idea? Then manufacture transitions from my existing 10x24 to the new 14x24 piece to improve supply air flow?

Then at the transition points, I go from the 12x21 HE I bought, one for each side of the supply....would that help with airflow?


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## beenthere (Oct 11, 2008)

Yes it will.

And your blower will appreciate it a lot.


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## AndrewF (Dec 29, 2008)

Ok, and then buy and install a balancing valve for the supply to the 2 HEs to ensure there is balanced flow to each, right?


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## beenthere (Oct 11, 2008)

Yes. But put them on the return from the coil.


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## AndrewF (Dec 29, 2008)

I picked up the 14x24x4' trunk pieces today...two sections...$90. Seemed high, but I suppose I have no choice. Hopefully I can do the change with only one section.


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## beenthere (Oct 11, 2008)

Your air flow will improve.
And so will your heating bill.


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## AndrewF (Dec 29, 2008)

Do you think putting in just a single section of the 14"x24"x48" trunk directly above the air handler, with a HE on each end of it where it transitions down to the existing 10x24 trunk is sufficient?

On the picture above, the connection to the trunk to the right, is behind the piece of conduit coming up from the water heater, about 5" to the right of the cut opening.

My concern in the photo below, is the one take off circled in red....there isnt an easy way to get it behind a HE. I may just fleave it there, since that room has a second one that comes from the trunk just out of the picture on the left.

The Humidifier...I should have put on the other side, and still may do that...so it gets hot air from the trunk after the HE.

The blue arrows mark the piece I would take out and put the 14x24 piece in.

It'll be tight on the right side, but I should be able to get the 12x21 HE in there with an angle'd up transition.


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## beenthere (Oct 11, 2008)

I would relocate that supply to after the coil. By using a side take off, and just run it close to the duct work until it can ell back up into the joist bay where it is.

You will want to relocate the humidifiers bypass line.

I would try and have the coils the same distance from the air handler on each side(not an easy thing to do with your current trunk set up).


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## skidrowpete (Nov 22, 2007)

*heat exchanger*

if u have an re michel company or look on internet for hydrnic coils from the FIRST company have them in both my houses to suplement my heatpump


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## AndrewF (Dec 29, 2008)

beenthere said:


> I would relocate that supply to after the coil. By using a side take off, and just run it close to the duct work until it can ell back up into the joist bay where it is.
> 
> You will want to relocate the humidifiers bypass line.
> 
> I would try and have the coils the same distance from the air handler on each side(not an easy thing to do with your current trunk set up).


Since that is one of the closer registers and I usually have the damper about 1/3 the way closed, I guess adding an extra elbow has a minimal effect on the CFM for that duct, right?

Each HE will be about 4" from the furnace supply. That gives me enough room to get 2 sets of 3 turning vanes above the AH.


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## beenthere (Oct 11, 2008)

AndrewF said:


> Since that is one of the closer registers and I usually have the damper about 1/3 the way closed, I guess adding an extra elbow has a minimal effect on the CFM for that duct, right?
> 
> If you use a round start collar, and then an ell it won't have much effect.
> If you use a take off, it will decrease air flow a lot. I made that mistake once or twice.
> ...


That should be good.


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## AndrewF (Dec 29, 2008)

If I dont buy a balancing valve this season, the "worst" that would happen is that one heat exchanger would possibly get more GPM than the other, right? Is this likely to change during operation or should it be pretty consistent once set up?

My thought is that since I have more SQ being heated one direction of my supply trunk than the 2nd HE would handle on the other side, I could just put in a ball valve on the one with lower SQ being conditioned and close it however much it took to maintain an equal temp of the air through each HE. (I have the valves and was hoping to not have to spend another $80 right now on a balancer.)

I was originally thinking of soldering in a T in the 1 1/4" copper line from the boiler that currently steps down to 1" pex and goes to one HE. It would be easier if I can just splice a 1" PEX T instead.

Do I need to be concerned with a GPM restriction of going that route and loss of efficiency?


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## beenthere (Oct 11, 2008)

Ball valves generally don't make good balancing valves.
But. You can do it, and see how it works.


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## AndrewF (Dec 29, 2008)

I got it all put back together and working. I have a few piece of metal to fabricate up to seal around the heat exchangers and the tie in to the old trunk.

I decided to plumb them in a series for now and see how well this works. I dont have probes on the supply and return water lines to see what the temperature drop is.

My thermometer in the trunk that is fed 2nd (right side of photos), has a temperature reading of 12 lower than the supply fed by the heat exchanger that gets hot water first.

This is fine with me, as the side that I have getting cooler water temp, has a lot less SQ of house to heat.

If I wanted to lower the temperature the boiler kicks back on, that is the little "lever" on the temp wheel in the last photo, right?

I understand how to change the high limit.


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## AndrewF (Dec 29, 2008)

http://192.168.1.20/chart.php?id=15Temperature readings with the Heat Pump on.

Thermostat 
72°

HVAC Return 
73°

HVAC Supply - North (1st HE on the left)
125°

HVAC Supply - South (2nd HE on the right)
129°

HVAC Suction 
100°

HVAC Liquid Line 
79°

HVAC Condenser 
12°


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## beenthere (Oct 11, 2008)

That should be a cold start boiler, and only have a single aquastat. The temp you set it at is its off temp. It should be a fixed differential. So you won;t be able to adjust it.


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## beenthere (Oct 11, 2008)

What was the OD temp when you took those readings.


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## AndrewF (Dec 29, 2008)

beenthere said:


> That should be a cold start boiler, and only have a single aquastat. The temp you set it at is its off temp. It should be a fixed differential. So you won;t be able to adjust it.


Ok, so that thing that looks like a lever on the wheel, does nothing? I notice that when I rotate the whole wheel, the temperature changes. So I wasnt sure if that "tab/lever" was the low set point.



beenthere said:


> What was the OD temp when you took those readings.


18F.

I do have my electric heat strips still in there, I'll do another heat rise test after I button everything up to see where my CFM is at.

I will say that having air temps above 100 coming out of the vents does make the house feel warmer.

Now I can stop getting up at 4am to feed the wood stove insert.

Beenthere, thank you for all of your input on this project.


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## beenthere (Oct 11, 2008)

Your welcome.

The tab is a safety stop so it can't be set above 240° or some temp like that.

The vapor line should be about 100°F above outdoor ambient temp. So yours is a bit low.
They summer, when you have the charge checked. They will probably find its a bit over charged.
Once corrected, you get better heat from your system next winter.

Bet it will be nice to sleep in tomorrow.


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## AndrewF (Dec 29, 2008)

beenthere said:


> Your welcome.
> 
> The tab is a safety stop so it can't be set above 240° or some temp like that.
> 
> ...


SLeep in? HAH! 

We do have the t-stat set at 75 now...house is much cozier. Hopefully I can stop running the electric heaters in the boys room at night. 

Yeah, its never been 100 above outdoor temp. I vaguely remember making a post about that a year ago...if it was normal or not.

I also am measuring the suction temp at the AH. Shouldn't I be measuring it close the the outdoor condenser? Even though the suction line is insulated from the condenser, it is about 30' of pipe to the AH.


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## beenthere (Oct 11, 2008)

Generally it would be measured within 6" of the service valve.

75? Thats toasty temp. :laughing:

Well. Sleeping until 5 instead of 4 is sleeping in isn't it.:thumbup:


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## AndrewF (Dec 29, 2008)

beenthere said:


> Generally it would be measured within 6" of the service valve.
> 
> 75? Thats toasty temp. :laughing:
> 
> Well. Sleeping until 5 instead of 4 is sleeping in isn't it.:thumbup:


I have an extra probe, I might put it on the suction line just inside the house, so it is not susceptible to outdoor temps.

Going to bed at 1, getting up 4 hours later...really messes with ones REM sleep. 

Toasty, you bet. The HP couldn't get the house this warm when it was cold, without costing me a year of my retirement 

This week I'll be rigging up sensors on my boiler so I can measure run-time and from there figure out the approximate gallons of diesel I use per day. If my nozzle is rated at .85 gph, how accurate is that? Meaning, how much can it change based on the PSI my burner pump is generating?

Are you familar with remote fuel oil tank gauges?

This tank appears to have one in it, the wires coming from the tank are capped off in a gang box in the basement. I have no idea how to see if they work, short of putting an OHM meter on it.


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## beenthere (Oct 11, 2008)

Can't tell you how accurate they are.
Should be the same as a cars gas tank as far as operation though.

GPH can be a lot different at 140PSIG then at 100PSIG.


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## beenthere (Oct 11, 2008)

So how did it work this winter.


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