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  1. #1
    Join Date
    Sep 2007
    Posts
    132

    Desuperheater in reverse

    This may be a dumb question, go ahead and slam me if it is.

    I'm thinking of different ways to boost the water temp of a geo system, increasing capacity as a result.

    Say I had glycol circulating through a solar panel on the roof, and down through the desuperheater connections on the heatpump. How hot would the glycol running through the HWG coil have to be in order to boost the refrigerant temp enough to see a benefit to the system? Retrofitting this on an existing system would be easier than opening up the ground loop to add in a heat exchanger. Would this even work?

    Of course, the system would be disabled in cooling mode, and the solar used to heat domestic water or a hot tub or something. And controls would be set-up to keep the solar loop shut down when glycol is too cold.
    There's a lot to know.

  2. #2
    Join Date
    Dec 2006
    Location
    phoenix
    Posts
    106
    You're asking our solar system to add heat the hottest part of the refrigerant circuit. Glycol deteriorates at higher temperatures. Glycol decreases heat transfer. Why spends thousands to save pennies. Etc,etc,etc. Why ??

  3. #3
    Join Date
    Sep 2007
    Posts
    132
    Told you it was a dumb question.

    This is more of a "will it work" question. Not "is it cost effective" question.

    Another way to ask it would be: Can you increase the capacity of a geo system by circulating hot water through the de-superheater/HWG coil? Ignore the economics of it.
    There's a lot to know.

  4. #4
    Join Date
    Oct 2008
    Location
    Northeast PA
    Posts
    257
    I have a solar Geothermal Hybrid system. Goto the My new geothermal system thread and read just the recent posts. I'm posting a day of data today which shows a day where the temp outside is in the teens and yet the geo loop increases in temp as the day goes on because of the solar.

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,397
    Quote Originally Posted by tunaguy View Post
    You're asking our solar system to add heat the hottest part of the refrigerant circuit. Glycol deteriorates at higher temperatures. Glycol decreases heat transfer.
    Why spends thousands to save pennies. Etc,etc,etc. Why ??
    Not sure that is what he is asking.

    @beer30.

    I'm not familiar with geo stuff, but I think I get the idea you are driving at. You want to use the solar heat during heat mode, to effectively heat up the ground loop and raise the evap temperature thereby gaining more heat?

  6. #6
    Join Date
    Sep 2007
    Posts
    132
    Thats right JP. But instead of tying the ground loop and solar loop together with a heat exchanger, I'm asking if it would be effective to run the solar loop through the HWG coil already installed on a heatpump.
    There's a lot to know.

  7. #7
    Join Date
    Feb 2006
    Posts
    468
    Nope. That superheated gas is already quite hot, and, being a gas it has low specific heat, so adding more raises temp relatively more. If you did find a way to significantly raise the temp of that hot gas still more you might bump up against working temp limits of the compressor oil.

    Much better to add solar heat at a high specific heat / low temperature area of the system. Adding it to the entering water strikes me as the most effective place for that.

  8. #8
    Join Date
    Jan 2007
    Posts
    1,359
    Can you just take a upflow unit and install it in the downflow position to accomplish that??

  9. #9
    in theory it would work but the problem is you can over heat the compressor and lock out on high head. if you were to use another heat exchanger for the ground loops only then you can increase the temp going to the ground and therefore increase the temp coming back to the compressor increasing the performance of the system. use the ground to absorb some of the heat because solar can get very hot.

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