"JohnW" wrote in message
...
I take it back. On setting 7, the heat pump comes on but nothing will
trigger the propane. Interestingly, I replaced the OLD thermostat, and the
propane comes on, but NOT the heat pump. What the hell...

What is the current outdoor temperature, and what was it when the HP was
running? Most likely you have an outdoor temperature sensor that 'locks out'
the HP when the OD temperature is below (fill in the blank) degrees..