What flow rate do you need?I am preparing to install a 2.5T geothermal heat pump and would like to use water from a 3 acre pond adjacent to the house. The pond water is quite clear but I have not yet had it analyzed for mineral content, etc but will soon do so. I would prefer to use an open loop, bringing in water from near the deepest point, about 8 feet.
What is the best way to filter the water from organic matter and debris? I am thinking of a fine screen at the inlet then a container near the bank, say something like a 55 gal drum, filled with clean sand to filter out the remaining contaminants. I'm thinking I could have inlet and discharge configured identically so I could occasionally reverse the flow and backflush the sand filters. The two inlet / discharge points would be far enough from each other to prevent thermal crossflow.
I am not too worried about eventual corrosion of the heat exchanger (mine have copper vs the cupronickel exchanger) because I have 6 identical working FHP heat pumps recently removed from service during an apartment complex demolition. I can afford to swap out units a couple times if heat exchanger corrosion or sedimentation is not too rapid. Fortunately, I have access to the technician who maintained these heat pumps and who is very familiar with their performance and service records - both excellent.
I would prefer an open loop if possible, but will consider a closed loop sunk in the pond if necessary.
I have monitored the water temperature at depth for the past year and it stays well within the recommended inlet water temperature range for my heat pump.
Any recommendations based on experience with open loops would be appreciated.