Hello, I have been having a minor issue with my carrier furnaces and air source heat pumps that I have been trying to figure out. I am not sure if it is actually an issue with the thermostat (I am leaning toward this being the cause) or the furnace/air source pump. What is happening, is even though the outdoor temperature has not reached the cutoff threshold for the air source pump to shut down, every 12-16 hours the system calls for auxiliary heat and burns the natural gas for about 2-3 minutes. This actually happens on both systems setup in my home. At the time, I have the temp settings set to remain at one temperature for heat, and the air source heat pump when it operates keeps the temperature steady, when the natural gas cycle kicks in, it is normally already at the setpoint temperature. The main problem with it operating this way, is when I switched the gas off on the furnace, it prevents the heat from running unless I manually shut off the system and start it back up again, at which time the air heat kicks in and keeps it heated until the next gas cycle is attempted.
I do not have the model # for the thermostat at the moment, but the same thermostat is on both systems, and both have the exact same issues. If I have the gas turned on on the systems, it does not have issues where it will remain trying for the gas heat after its cycle, cutting off the heat until it is manually turned off etc. The whole idea of using this setup was to not need to run the gas as much during the warmer cool months...but it is annoying me that it is not running only on the air source heat when the temp is still steadily 25-30 degrees above the cutoff for the air source pump, and the pumps are keeping the temperature up where it is supposed to be otherwise.
Is it a normal operation for it to run a cycle on gas to basically test the backup heat or something? Any help would be great, I was just wanting to see if it is a normal issue before contacting the furnace installer regarding it.