I state with confidence, that wiring to a millivolt fireplace/stove/space heater with almost any smart thermostat, including the Wyze, is as simple as;
24v transformer to Rc and C
Heater leads to Rh and W1
Rc and Rh must NOT be connected
This solution has worked for me for years and with several different thermostats.
Did not work for me. With separate transformer the thermostat could not accurately sense room temp. The reading wandered all over the place.
When i isolated the thermostat from the condensing furnace with a simple relay - everything worked.
Thanks for this post, appears to be working! Purchased the C adapter transformer that you recommended. I had to skip through warnings that my wiring was wrong during setup. Also chose the option that my old thermostat had the wirings for a heat pump but that I don’t actually have a heat pump (both true).
Haven’t checked how accurate the temprature actually is, but it feels reasonably close, and it the heat quickly responds when I turn it up/down on the phone app.