Pennsylvania Question about desuperheater with propane WH

Discussion in 'General Discussions' started by cwb124, Jun 14, 2016.

  1. cwb124

    cwb124 New Member

    I'm in SE PA and about to have a geothermal system installed with a desuperheater. Talking to the engineer, the winter time expected closed loop temp will be around 35-40 degrees. City water comes in the house at around 50 degrees. At these low propane prices (I just filled up for $.76/gal), would it make sense to continue using propane to heat the water from 50 degrees to 110 in the winter rather than the desuperheater working "harder" to bring 35 degree water up to 110 degrees? Maybe I'm nitpicking a few bucks here and there, but with these low propane prices and it's ability to heat a lot of water quickly, maybe it makes sense to keep using fossil fuels to heat my water in the winter until those prices rise. Am I way off base here and not understanding the efficient nature of the desuperheater?
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Keep in mind that that most propane or gas tanks work inherently inefficient. After standby heat loss, cycling losses and combustion losses are accounted for, you are sometimes do not get more than 50% out of it.

    Plus you are installing this not for now, but for the years to come. And there are some DSH benefits in the summer time, where it runs more efficient, collecting the heat you would otherwise reject into the ground. For the second tank you can have the argument wether propane or electric resistance heat would be better, but for the buffer I would always go with a DSH.

    You could expand the argument and ask yourself if you should put a propane heat system now instead of the geo system?
     
  3. cwb124

    cwb124 New Member

    Today, geothermal does not make sense over propane at these prices. But like you said, I'm playing the long game here and I do remember 2 years ago when propane was $3/gal. I'm not suggesting not putting the DSH in, I'm just pondering if these propane prices continue through the winter if it's more efficient to heat my water with propane when the DSH is at its least efficient in terms of generating hot water. Probably difficult to calculate.
     
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It is not that hard to calculate.

    What is your heating and cooling load? How many people in the household?
     
  5. ChrisJ

    ChrisJ Active Member Forum Leader

    Your water coming in is 50*F regardless of what temp the loop is at. If the DSH is able to raise it to even 70 or 80, that much less the propane water heater has to work.

    The un-powered electric tanks are better at maintaining temp, You can find them with 3" of insulation.

    CJ
     
  6. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Yep.
    Yep
    Yep
     

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