air handler heat exchanger location question

[Canton]

I have a question concerning the placement of the water to air heat exchanger in the air handler plenum. It appears the only two options I have are to place it directly above the AC coil and directly below the humidifier or directly above the humidifier, which will be directly above the AC coil. I'm not sure which would be better. I would think above the AC coil but below the humidifier would be most beneficial for picking up the humidity with the warm air. Thoughts? suggestions?

Jeff.

 

[mtfallsmikey]

Upflow, horizontal, or counterflow? I would put it between the humidifier/A.C. coil if possible. You may have to bump up to the next highest fan speed after that is installed, it will add some static pressure load, but try it first.

 

[greendohn]

I have a downdraft , l.p. furnace, duct work is all under the floors. My heat x-changer is mounted on top of the furnace at the cold air return. I had never given it a second thought until a hi-vac guy I know mentioned it should be mounted at the very bottom of the furnace, below the a/c coil.
I'm in no hurry to pull my furnace out and re-install the x-changer in the bottom of my furnace. I understand that heat is hard on the blower assembly and will probably lead to a shorter service life of the blower assembly,,

 

[Butch(OH)]

Ours is as Mike said. We do run the fan on high for heating. We also put heat excahnger sits on two angle iron rails so it can be slid out of the plenum in the summer. Most dont do that and get along just fine but my A/C is marginal anyway and I didnt want the rsisitance to flow in the summer.

 

[Canton]

It's an updraft unit. Main concern was the close proximity to both the AC and humidifier. I did know about check the fan speed for both AC and heating because of the increase in resistance. If need be, it can be removed during the summer, but I'm trying to avoid that if possible. Thanks for the information.

 

[mtfallsmikey]

I have a downdraft , l.p. furnace, duct work is all under the floors. My heat x-changer is mounted on top of the furnace at the cold air return. I had never given it a second thought until a hi-vac guy I know mentioned it should be mounted at the very bottom of the furnace, below the a/c coil.
I'm in no hurry to pull my furnace out and re-install the x-changer in the bottom of my furnace. I understand that heat is hard on the blower assembly and will probably lead to a shorter service life of the blower assembly,,

Mine is counterflow as yours, I installed my HX on the bottom while replacing the furnace, A-coil, etc. Problem I have is that when the fan is off, I get ghost flow thru the HX, it rises, and cuts the fan on intermittently, still wired up thru the low/hi limit switches, not a big issue really.

 

[Encore]

In between the humidifier and the AC unit.

I would imagine you could run the risk of in the summer with the AC running full tilt, of freezing any water in the heat exchanger if it is above the AC coil.

I could be wrong though.

 

[Canton]

I've read concerns of heat exchangers freezing from being in above the A/C coil, but I can't harldy believe this. I would think that would be more of an airflow issue than anything else, or one hell of an A/C unit. Hoping not to have to remove it in the summer, but at least my plumbing will support it if needed.

 

[Encore]

I agree, it does seem unlikely. Maybe some of the more experienced HVAC guys on here will chime in, but maybe its the contact with the A coil that could possibly bring down the water temp enough to freeze? I'm not sure.

My AC would certainly run long enough at times to cause it to freeze if it actually got cold enough but I thought normally the freon at the A coil only got down to around 40 degrees?

 

[mtfallsmikey]

That is really not an issue. If the evap. coil gets that cold, it will freeze itself up, no air would get by it.