I have a Trane heat pump system that's about 20 years old in my house. Model # TWE036C140B0. I recently self installed a new Honeywell thermostat, and while it runs fine my energy bill has been increasing. The thermostat is constantly using auxiliary heat. I'm starting to think I should've programmed it to be a multistage A/C instead of single stage, but I don't know if it's multi heat and multi cool or multi heat and single cool.