Thanks so much.The defrost is controlled entirely from you heat pump outside. When the thermostat is calling for heat and the temp sensor is below a set temp a timer runs on your defrost board. Every so many minutes of runtime below the temp sensor setpoint the unit defrosts. The electric heat being turned on etc is all controlled from outside & has nothing to do with the stat on any system i've ever seen.
The stat only controls the reversing valve (except for defrost, then it's controlled from the defrost board), the heat pump turning on/off and the aux heat turning on/off.
I really appreciate it.