Bubba wrote:
Travis
Electric back up heat is NOT inefficient. It is actually 100%
efficient. That doesnt mean it isnt expensive to operate.

Hi Bubba -
I didn't say anything about the efficiency of resistive heat.

I agree that a hack might have miswired the aux heat to come on whenever
the heat pump was operational - and they could have done that with a
jumper at the old thermostat. From the OP's description it sounds like
the new thermostat is wired correctly in this regard.