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  1. #1
    Join Date
    Nov 2010
    Location
    Montreal, Quebec.
    Posts
    71

    HP coil in return duct

    I am having a gas furnace and heat pump installed. This is a northern climate house so the furnace is in the basement with a plenum and trunks. The old furnace had the HP coil above the furnace in the plenum. One installer is talking about putting the coil in the return duct, he says it's more efficient that way. What do the Pro's think.

  2. #2
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    2,029
    Quote Originally Posted by Norm01 View Post
    I am having a gas furnace and heat pump installed. This is a northern climate house so the furnace is in the basement with a plenum and trunks. The old furnace had the HP coil above the furnace in the plenum. One installer is talking about putting the coil in the return duct, he says it's more efficient that way. What do the Pro's think.

    Is he installing an air handler? It has been common practice that an Air Handler pulls air across the coil while a gas furnace blows air across the coil. However even the new Trane air handlers are now pushing air across instead of pulling across air. Without knowing what system you are having installed this does not meet my equipment specs.
    Check out my YouTube channel - http://www.youtube.com/user/skyheating1 We have customer testimonials, product reviews and more!
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  3. #3
    Join Date
    Nov 2010
    Location
    Montreal, Quebec.
    Posts
    71
    Installing gas furnace with blower, return comes in the side of the furnace and plenum on top.

  4. #4
    Join Date
    May 2011
    Location
    Ripley, WV
    Posts
    1,331
    Sky, I've always been told that if you pull through the coil and then across the heat exchanger it can cause condensation on the HE and possibly lead to premature failure. Would you agree or disagree?

  5. #5
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    2,029
    Quote Originally Posted by Rob_in_WV View Post
    Sky, I've always been told that if you pull through the coil and then across the heat exchanger it can cause condensation on the HE and possibly lead to premature failure. Would you agree or disagree?
    Exactly, I realized I didn't specify the reason why I disagreed with the installation so thanks for helping me out lol.
    I think the installer is just used to doing air handlers and not gas furnaces, but I would not allow that installation in my house or any house that I work on. In fact in my years I have not even seen a gas furnace installed this way. Is it to late to find another contractor to perform the work?
    Check out my YouTube channel - http://www.youtube.com/user/skyheating1 We have customer testimonials, product reviews and more!
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  6. #6
    Join Date
    Nov 2010
    Location
    Montreal, Quebec.
    Posts
    71
    Not too late and he will do it the way it was however he did not recommend it. Thanks for the reply's.

  7. #7
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    1,058

    I would

    be willing to bet if they read the installation manual, they dis-approve of putting the evaporator coil before the heat exchanger. There was some talk about it being OK if the heat exchanger were aluminu or stainless steel, but I still would advise against it.You will be better off with the coil on top of the furnace and using the proper controls. JMHO

  8. #8
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,198

    Rob is right

    Quote Originally Posted by Rob_in_WV View Post
    Sky, I've always been told that if you pull through the coil and then across the heat exchanger it can cause condensation on the HE and possibly lead to premature failure. Would you agree or disagree?
    WHAT HE SAID!!!!!!!!!!!!!
    DON'T LET HIM DO IT
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  9. #9
    Join Date
    May 2011
    Location
    Ripley, WV
    Posts
    1,331
    Quote Originally Posted by SkyHeating View Post
    Exactly, I realized I didn't specify the reason why I disagreed with the installation so thanks for helping me out lol.
    I think the installer is just used to doing air handlers and not gas furnaces, but I would not allow that installation in my house or any house that I work on. In fact in my years I have not even seen a gas furnace installed this way. Is it to late to find another contractor to perform the work?
    No prob. I was hoping I wasn't stepping on your toes by bringing it up.

  10. #10
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,312
    You shouldn't put a coil before a heat exchanger.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  11. #11
    Join Date
    Jan 2008
    Posts
    2,117
    I would not let anyone install anything if they first suggested the coil in front of a heat ex-changer. I can only imagine what other screwy ideas they might come up with, or corners they might cut.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  12. #12
    Join Date
    Feb 2011
    Location
    North East Ohio
    Posts
    786
    Quote Originally Posted by Rob_in_WV View Post
    Sky, I've always been told that if you pull through the coil and then across the heat exchanger it can cause condensation on the HE and possibly lead to premature failure. Would you agree or disagree?
    I agree with that. It makes perfect sense

  13. #13
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,062

    Thumbs down

    Quote Originally Posted by Norm01 View Post
    I am having a gas furnace and heat pump installed. This is a northern climate house so the furnace is in the basement with a plenum and trunks. The old furnace had the HP coil above the furnace in the plenum. One installer is talking about putting the coil in the return duct, he says it's more efficient that way. What do the Pro's think.
    International Fuel Gas Code 627.8

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