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[Treewinder]

On my hot air furnace due to very low head room the supply duct is 12" high and 24" wide before branching. In that configuration there is no way to install a water to air exchanger.  I was thinking about a transition but that will put it at shoulder level in the way of a doorway, not really acceptable.

Has anyone used the return duct as it enters the furnace for the location of the exchanger, on that side it is 24"x24".

Thanks for any input

Ed

[willieG]

On my hot air furnace due to very low head room the supply duct is 12" high and 24" wide before branching. In that configuration there is no way to install a water to air exchanger.  I was thinking about a transition but that will put it at shoulder level in the way of a doorway, not really acceptable.

Has anyone used the return duct as it enters the furnace for the location of the exchanger, on that side it is 24"x24".

Thanks for any input

Ed

that is very close to the size of the duct on my home system as well..i cut a slice in the duct and installed two 12x 14 water to air exchangers. i just overlapped them a little. you must be sure there is no room for air to move around the exchangers as the air will take the route of least resistance.

[RSI]

On my hot air furnace due to very low head room the supply duct is 12" high and 24" wide before branching. In that configuration there is no way to install a water to air exchanger.  I was thinking about a transition but that will put it at shoulder level in the way of a doorway, not really acceptable.

Has anyone used the return duct as it enters the furnace for the location of the exchanger, on that side it is 24"x24".

Thanks for any input

Ed

that is very close to the size of the duct on my home system as well..i cut a slice in the duct and installed two 12x 14 water to air exchangers. i just overlapped them a little. you must be sure there is no room for air to move around the exchangers as the air will take the route of least resistance.

Why didn't you just use one 12 x 24 heat exchanger?

[RSI]

On my hot air furnace due to very low head room the supply duct is 12" high and 24" wide before branching. In that configuration there is no way to install a water to air exchanger.  I was thinking about a transition but that will put it at shoulder level in the way of a doorway, not really acceptable.

Has anyone used the return duct as it enters the furnace for the location of the exchanger, on that side it is 24"x24".

Thanks for any input

Ed

Can you post a picture of what you have? I have heard a lot of people that have put the in the return but if you talk to an HVAC contractor they won't do it. They say the heat will damage parts of the furnace on the return side.

[Treewinder]

Thanks for the replys,

"Why didn't you just use one 12 x 24 heat exchanger?"  -- BTU output for those is around 120K, need around 150K, but that is an option.


"installed two 12x 14 water to air exchangers. i just overlapped them a little"   -- Did that effect your fan blowing thru two exchangers?

"Pictures" -- Will have to get some pics over the weekend, I attached a sketch if it comes out.  The transition area is where the head room is too low. Where the 12"x'24" goes into main, it branches to different areas of the house, guess could put one in each direction.

But does seem that putting in the return is not a good idea.
Ed

[Bull]

I put mine in the return right on top of the furnace. To put it on the supply side would have required raising the furnace (down draft) and there was not enough slack in the ac lines.

[rhugg]

I saw that one of the manufacturers noted that the outlet side is preferred.  I do not see a problem with the HE in the return side if you can get some filtration in front of it.  If not you will clog the HE up over time.  If you can't get filtration in front of it you may want to check it/clean it periodically.

[RSI]

I saw that one of the manufacturers noted that the outlet side is preferred.  I do not see a problem with the HE in the return side if you can get some filtration in front of it.  If not you will clog the HE up over time.  If you can't get filtration in front of it you may want to check it/clean it periodically.

The reason they say not to is because they use plastic parts in newer furnaces that can not take the heat. I would only put it before if there is no other choice but make sure it is after the filter.

Just curious, you say you need 150K btu. Is this what your current furnace is or did you get that number somewhere else?

[Ridgekid]

I was told by our furnace supplier to have the heat exchanger down stream of the furnace fan due to heat. Although my air handler is designed to draw the heat across the "heatpump" exchanger, it's cooler than what my OWB will be suppling.

[dirtryder]

I have mine in the return just below (before) the fan. I actually had to drop the filter and installed HX between filter and fan. I did this to 2 units. 2 years, no problems at all.

[Treewinder]

Thanks for the replies and suggestions and the descriptions of what you each did, I think I'm going to try RSI suggestion and got with the 12X24 exchanger.  If lacking on heat, I'll double up on each main directional branch.

Here's the same pic with the doorway that requires I keep that shallow headrrom.

[6pacmac]

The heat exchanger on the return side will be harder on the blower motor. It won't have any colder air to keep it cool.    It wiil always bathed in hot air while running,  as long as hot water is in the heat exchanger.  When I was in the restaurant biz,  it seemed we always had a exhaust fan motor fail in the summer time.   Cause they're in the hot air all the time.

[oldchenowth]

I have mine in the cold air return.  I had an HVAC guy make me a plenum that fit right into the space I took the section out, running a 24x24 HX and seems to work great.  I have heard about heat affecting plastic pieces on the internals, but have not experienced that yet myself.  Filter is key though!  I am going to put a filter just in front of the HX and also have fliters at my only return vent. HX does get dirty, hence the second layer of filtration.  All in all, I am very happy with my setup. 

[bruey]

i put mine on the return side, just wasent any room anywhere else, the hvac guy that sold me my furnace told me to keep the thermostat set at 170 or below and i will be fine. he said most furnaces are rated at 180 for internal temp. 3 years now and no problem, did cut in an air filter above on the return side.