I am trying to replace a dumb (no wifi) battery powered thermostat with a smart (t5 honeywell) thermostat.
It is cooling only.
The old thermostat had a Y, G and R wire (heat pump and fan). I have since been able to install a 24 v transformer and can bring 24 v to the thermostat so it has enough juice for the T5 smart honeywell.
I know that one end of the 24v goes into the C. But I am not sure where to put the other end goes. I have tried putting one in Rc and the other in R. But the system does not work.
Does the thermostat come on at all? What kind of system are you trying to operate with this thermostat? Did you make sure the transformer you used is an AC output and not a DC output?
Did you set the R switch to the up position?