[buffalobillpatrick]

GSHP shallow loop:

I'm thinking of adding a 1000' loop of 1" HDPE outside basement (no underground joints). This would be pretty easy as excavation hole is 8' larger than basement on 3 sides, it's a walkout.

I'm getting 120ft2 more of used hot water solar panels cheap, total will be 360ft2, tank is 1000 gallons.

I should have excess solar heat every month to recharge this loop.

My water well fills to about 30' below surface, artesian effect.

I think that heating up the soil (decomposed granite gravel) around basement will lower the Delta-T through the basement ICF walls, which will lower heat loss below grade a bit.

Also in longer weather periods of poor solar gain, my Heat Pump may draw heat out of solar storage tank down to minimum (say 33*) and then Heat Pump can source from this loop.