02-08-2022 05:42 AM
The old thermostat uses 3 wires, G, Y, and Rh jumped to Rc. The house was originally zoned oil hot water with 2 wire thermostats plus AC & air handlers added later. Connected as instructed only fan & cool can be accessed. At another location, Nest works fine and I can access the setup for the zoned heat (this uses a different air handler AC).