New to forum. Little knowledge of technical specs etc. Am from London, England originally so can just about change a light-bulb! I have had a geothermal vertical system installed last year and here are some details I know. Piping size entering/ leaving home 1.25” Piping size and length in ground .75” approximately, 600’ (plus another 125' added after installation!) 10kw auxiliary heat strips Comfort-aire Model HTV036A1C01ARK Hope someone can help with some pretty straightforward questions. Last year we has a brutal winter here for northern Kentucky! Temps got to 0.F and weeks below zero daytime. Set thermostat to 72.F and just let system do it's thing, as advised by installers. No set-back etc. Electric bills per month $450 (so about $300-325 on geo I estimate). Realized that not really saving much over our old (old) oil furnace, heating wise. (Air conditioning worked fine btw) Problem: Auxiliary heat comes on nearly all the time when outside temps drop below 32.F This winter started temperature reading at nearest register to unit in basement, (which is about 5' away) with Aux turned off to see how geo was operating. On a 40.F outside temperature it will put out 92.F Max. When outside temps drop below zero and lower, the register temps slowly drop to about 79.F. (which, understandably, cannot maintain acceptable heat in older home, hence aux heat coming on) I was under the impression that the output of heat from the unit should remain constant since geo isn't affected by outside temps. (like an air source hp) Am I wrong? Are these register temps within acceptable parameters (if there are any)? Thanks.