Quote:
Originally Posted by ledbalon
an air source heatpump has a thermostat that cuts the unit off at 37 degrees.
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My little unit is good to below 17F... I have watched it. Some of the newer ones are good to 5F.
Quote:
Originally Posted by ledbalon
...general rule is that one can suck enough heat out of the ground that it provides 4 times the BTU for the draw on the power to run the pump.
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I believe this is referred to as COP (Coefficient Of Performance).
COP = (energy-out) divided by (energy-in)
My homemade unit had a COP of between 3 and 7, depending on the source temperture (where the heat was coming from) and the sink temperature (where the heat was going to).
Regarding energy issues, you might want to check out a web site called
The Oil Drum
Very useful information about what's going on behind the scenes.
-AC