Quote:
Originally Posted by IndyIan
Diesel_John
I am impressed on your energy return from a pond, does the surface not freeze in the winter? Ian
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(heating)The COP of 3.7 to 4.2 assumes 32 degree entering fluid.
(cooling)The EER of 17 to 24 assumes 77 degree entering fluid.
My pond did not freeze over last winter for more than a few hours, because i have a wind powered air pump which pumps air under the ice. The column of bubbles coming up lifts/melts the ice. It tends to make the whole pond the same temperature, i don't know if it adds energy to the water or just brings up warm water from 20 feet down. But during the day which absorbs more heat from the sun water or ice? So maybe the sunlight adds more heat than the cold air takes away. I have read that air pumps should be turned off in the winter in geothermal applications. Because the bottom of the pond could freeze around the tubing reducing the heat transfer. I think moving water might prevent that. I am thinking it would be tough to get 0.9 million gallons of moving water down close to 32 degrees F. This pond has twice as much surface area in common with the ground as it does with the air.