Travis Jordan wrote:
"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..

It sounds like your dual fuel (HP plus propane) system is designed to run on
one or the other fuels depending on the outside temperature. That may not be
the most efficient paridigm, but it is one that is especially popular in the
northerneastern and midwestern parts of the U.S. Here in the south we run the
HP all the time (well, down to 25 degrees or so which rarely happens), and
supplement it with electric heat strips or gas if it is available.