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  1. #1
    Join Date
    Nov 2008
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    4

    Exclamation heatpump question? please help.

    Can you run a heatpump the same time as fossilfuel ? . or will you burnup the compressor. please elaborate.

  2. #2
    Join Date
    Feb 2007
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    out in the country
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    633
    Wrong forum, this is the convention forum. But to answer your question. Do not run both at the same time. You will be putting hot air over the indoor coil.
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  3. #3
    Join Date
    Oct 2008
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    That would just be silly. Not recommended and your system shouldn't operate that way if it is. Burning up the compressor? Maybe, possibility. this will lead to very high head pressure and could cause compressor failer. But compressors can and do take allot of abuse. so if it runs like that for a short time it probably will not kill the compressor.

  4. #4
    Join Date
    Sep 2006
    Location
    Leavenworth KS
    Posts
    305

    Smile HP and fossil fuel

    We install them often. Your installer should install a fossil fuel kit or a thermostat that turns off the heat pump before starting the Furnace.

    This is over simplified, but you get the Idea of how this works.
    Last edited by mgould2; 12-21-2008 at 09:41 PM.
    Mike

  5. #5
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,024
    Quote Originally Posted by mgould2 View Post
    We install them often. Your installer should install a fossil fuel kit or a thermostat that turns off the heat pump before starting the heat pump.

    This is over simplified, but you get the Idea of how this works.
    That's a neat trick, turn off the HP before starting the HP. Well I guess you have to turn off something before you turn it on.
    Beware of advice given by some guy on the Internet.

  6. #6
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,024
    Yes a heat pump can run at the same time as the furnace. It is actually an option in some duel fuel stats.







    Okay, before you all jump me. Some stats will leave the HP running while the HX is warming up. Then shut it off.

    I alway turn that option off.
    Beware of advice given by some guy on the Internet.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    Quote Originally Posted by Milk man View Post
    That's a neat trick, turn off the HP before starting the HP. Well I guess you have to turn off something before you turn it on.
    LOL...

    Except during defrost cycle, it is a bad idea to have the furnace and HP run at the same time.
    If the furnace was running at the same time, and the HP doesn't have safeties to shut it down, the compressor would start to overheat.
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  8. #8
    Join Date
    Nov 2008
    Posts
    4
    thanks guys, just need to prove my point at work.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,755
    Easy way.
    Is just to relate it to how the head pressure increases in summer as the outdoor temp increases.
    If a R22 system runs at 225 PSIG when its 95 outside. Think how much higher the pressure will get when its in heat mode with 13° air entering the smaller indoor coil.
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