I installed a ritetemp digital thermostat and appear to have 2 problems. 1) I’m not getting any ac to the thermostat, so it does not activate the furnace. I know I need to check the 24v transformer and common per the other threads. But, if I go to the circuit breaker panel and reset the furnace (80 amp) breaker, which is not tripped, everything comes on and works normally until the next heating cycle when the same symptoms appear. 2) I noticed that my heat pump breaker trips occasionally and I need to reset it a couple of times before it will reset. Any ideas?

Maybe wheatbarley left this one because he didn't know the answer. Maybe I should too. Still, a couple of questions. The system was working right before you changed thermostats? If it takes batteries, are you sure you have good ones in it. Does the new thermostat have a B or C contact, and if so, is it connected to a blue or other wire going back a B or C contact? Last of all, did the instructions describe hooking it up to a heat pump and any special procedures for one? Sometimes I manage to help people figure out things I don't know the answer too.

Labman,

Thanks much for the quick response.

The system was not working before I changed tstats (used to have a digital Hunter tsat – and constantly saw the “NO AC POWER” warning flashing on the tstat screen). I do have fresh batteries installed. The new tstat has a C terminal and I have connected the blue wire from the furnace to it. I also have black and brown wires – the instructions said to leave those disconnected and so I have. There was nothing specific about connections for a heat pump – I did verify that the tsat is compatible w/2-stage systems. Don't know if this helps clarify my problems (well at least those related to the furnace!)

If the old thermostat wasn't working either, that makes it more likely the problem is with the system or the connections and not the thermostat. If you do not have 24 volts at the R and C connection until you reset the system, the problem is in the system, not the thermostat.

The 80 amp breaker suggests to me it is a heat pump with resistance heat back up. They can be wired for the system or the thermostat to control the back up heat. If the thermostat controls it, it may be W1 and W2. A heat pump also needs signals to switch modes. Often that is an orange wire connected to O or O/B. The system could have a schematic showing the connections needed for the mode control. If the directions say nothing about a heat pump, that thermostat may not work.