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Old 01-10-19, 08:22 AM   #7
jeff5may
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In the wide scope of the entire system, your theory concerning ground loop pumping losses holds up pretty good compared to a pump and dump system. Since the brine solution is going in a circle, all you have to do is move the mass of liquid and the pump motor and some amount of friction. So a relatively long skinny slinky loop will use less power than a not so deep well pump.

How this affects the overall COP depends mainly on the vapor compression side of the system. Usually the refrigeration compressor uses a whole lot more power than the water pump to propel refrigerant through it's loop. That and sizing the heat exchangers properly bears much more on performance than trying to eliminate loop pumping losses.

As for the actual "cold fingers" pipes in the ground, I would probably go for the greenish 6 inch sanitary PVC pipe, due to cheaper. On the bottom, a cap or plug glued on. For the top, I would use a reducing tee and reducing bushing. Tee center connected to outside, small diameter pipe would ideally pass through the bushing to minimize glued joints. To be really snazzy, a bushing could go on the inserted end of the small pipe to keep it centered in the big pipe. Definitely use antifreeze, it would be way bad if ice rose to the top and tried to block the exit.
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