I have separate heating (hot water) and air handler (cooling System). The current thermostat I'm using is a Honeywell RTH2300B and the new one I want to install is a Honeywell Wifi RTH6580WF1001.
The current system allows me to toggle between heat and cooling and so will the new one but the old thermostat didn't require a common wire but the New one does. Both systems have 24 volt power and I have an extra wire that I can use for that but the question is witch system do I take The 24 volt power from.
I would like to take it from my boiler as it is also my water heater so it is powered on all year round but I can leave power to my air handler on also.
- The Green -G wire goes to the G on the Air Handler
- The Yellow -Y wire goes to the Y terminal on the Air Handler.
- The White -W wire goes to a zone valve on the Boiler.
- The Red-R wire goes to a zone valve on the Boiler.
- The Brown -Rc Terminal wire goes to the R terminal on the Air Handler.
Can anybody help me?
Best Answer
Honeywell thermostats (also Nest, and probably others) require the
Cwire to come from the cooling system, in systems that have multiple transformers.