Folks, as I am completing the design of my geothermal system with a vendor..... I keep coming back to fears that the units are undersized for my location, in terms of needing Auxiliary or backup heat more than I want.
From what I understand in the air-to-air world, most heat pumps are good until around 35-40F for reasonable efficiency if sized for teh heat/cooling requirements.... assuming that the sizing is correct, outdoor temp is important for both the compressor to collect heat as well as make sure the inside air temp is covered.
for example, is it true that if loop temps in winter sit at lower than 35 degrees, a geo theoretically won't do any better than a similar sized air-to-air in terms of needing aux/heat? correct?
So, sizing aside, doesn't it make sense to force loop sizes that would keep the temp of the water stable and in that range above 35 to the nominal ground water temp of 45-55 degrees?
Would there be more bang-for-the-buck with longer / deeper loops if the size suggested is on the low end?