We had a new house built and had geothermal installed. We just moved in 3 weeks ago. It's 33 degrees outside and the heat is on. The thermostat display shows "auxiliary heat on". I'm assuming that means the propane forced hot air backup is on. Should it be? Doesn't seem right.
Check the programming in your thermostat. If it isn't programmed correctly, it could be skipping stage 1 and 2 and going right to Aux. This was the issue we had when we first installed our geo system. In our case the electric aux was disabled (breaker off) and only stage 1 was enabled. Since it was air conditioning season, stage one was good until 88F degrees outdoor. That is when we discovered the programming issue.
In the Winter stage 1 is good down to about 5 F depending on wind and time of day. Stage 2 takes us down into 20s F below zero. Aux remains turned off at the breaker.
