Add-on furnace and AC coil

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Badfish740

Minister of Fire
Oct 3, 2007
1,539
My ESW 28-3500 is piped into the side of the plenum of my oil furnace in such a way that the hot air is blowing directly on a portion of the AC coil. I couldn't mount the pipe any higher so as to totally avoid the coil because immediately above the main trunk branches off of the plenum. I decided it wouldn't be wise to pipe into the trunk line because I thought it might starve two rooms of heat since the registers of those rooms are piped directly into the plenum. Anyway, I'm wondering whether or not to move the pipe somehow (not sure how yet) because of potential issues with the AC coil-I read a brief thread on the subject a while back. However, I'm also wondering if it will cause any damage because my oil unit blows hot air directly THROUGH the coil anyway. Is the air coming out of my add-on that much hotter? I suppose I could test it if I had the right tools but I currently don't. Anyway, I was just wondering if anyone could give me some guidance since I don't want to have saved a bunch of money on heating oil through the winter only to have to spend it on a new coil this summer. I've only been burning (overnight for about 8 hours at a clip mostly) for a week so far-would that be enough to cook the coil?
 
Heat from a wood appliance can be up to 500-600 degrees.
Therefore you'll want a back flow damper between the wood heat run and the A/Coil.
You most likely have a plastic condensate pan that can melt from the wood heat.
You also want the heat to move in the right direction through your ducting.
You can call me to discuss your setup and I'll do the best I can to resolve your ducting issue.
 
I love the link in your sig Badfish!
Long live the 2nd amendment!

np
 
Is there a way to direct the heat away from the A-coil, maybe install a damper or piece of tin so that the air deflects away from the A-coil? I have the same thing, but I put my ductwork through the plenum over the top of the A-coil so that the heat actually comes out past the A-coil (if that makes any sense). I guess it kind of depends on how your plenum is set up.

Edit: I looked at your install pics. If you install your 8" around the back from where you originally installed it and up higher sending it through the plenum into the main trunk you could avoid the a-coil and you wouldn't get backblow. I don't think the A-coil goes that far up. Unless I am missing something on the back side. That is pretty much exactly how my furnace works. You will get better air movement too with it that way.
 
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