We are trying to minimize our propane usage. Recycle Reuse Reduce. One kitchen garbage bag every two weeks, second hand and thrift stores for clothing, buy it once philosophy.
It seems like the heat pump is running non stop at 10 and below and at 5 it doesn't maintain the desired temperature. The propane is already paid for so it seems to make sense to run that until the temperature rises. Saves us money on the electric bill.
We have to switch to manually, usually 10 degrees is the cutoff. ..We find that the heat pump struggles and runs constantly driving the electric bill up. We have a large credit from a prepay propane purchase from a few years ago.