The COP of a geothermal heat pump is given for inlet water temperatures in the
range of 30-50F as being from near 1.5 to about 3.0. Does anyone have any data
on what the COP would be if the inlet temperature were raised to about 75F by
low-grade solar heat?
I currently have a "Water Furnace" brand heat pump with a closed-loop feed
system. I am trying to decide if I should add solar heat using an independent
system, or if I should use the solar heat just to boost the efficiency of my
heat pump, One of the advantages of the second approach is that I can make use
of lower temperature storage of solar heat, as opposed to the direct method.
But the second approach won't do me much good unless it significant raises the
COP of the heat pump.
Your COP will increase greatly.
Contact Water Furnace, a WF dealer, or check their website & get the
They should have the heat production capacities for a wide range of EWT's.
COP's should be clearly stated or easily calculated.
Make sure you isolate the solar panel system from the loop field w/a heat
exchanger & circ pump, as the sun isn't constant & the panels may/will have
a huge heat drain on the loops system on cold nights in the dead of winter.
The increased antifreeze quantity required, without panel isolation, will
also (negatively) effect the systems operation.
You could look at a indirect water heating tank with loop field water
circulated through a tube inside a tank of solar heated water. When the sun
shines you crank up the solar panel pumps & heat the tank as high as you
can. When the suns down the tank will drop, but shouldn't drain the loops if
properly installed. You could even have a secondary pump on your loop to
tank tube that "injected" warmer water from the tank exchange simple temp
controls will run the pump until tank temps & loop return temps are near
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