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How to wire a smart thermostat? Dual Transformer system? R , Rc, W , Y , G. No C wire?
Is this system considered a Dual Transformer system? According to Nest since there is a R and RC cable it must be a dual transformer. But they were unsure and I don't know what that means! I don't have a C wire. Trying to figure out which smart thermostat is best suited for such a setup and hook it up without tearing up much or pulling new wires!
Hope the picture makes sense. I currently have a Honeywell Thermostat with the following wires hooked up.
R, RC, G, Y , W. No jumpers. I have a FirstCO Air Hnadler, Burnham Heat, and AC unit outside the house. Current Thermostat: Honeywell TH6220D1002 FirstCo Air Handler: 30MBX-3HW 120V-1PH-60HZ
- ?Lv 51 month ago
I'm geussing your old thermostat had a wire hooked to R an one to RC Doubt you have a dual transformer system. Your A/C has a 24v control system. Your gas furnaces problem runs on millivolt. Which is just the natural voltage on a closed circuit.
If you have a spare wire between the furnaces an thermostat you can use that as your common. You'll hook it to the common side of transformer. If I remember right nests have to have common theres no batteries. But I could be wrong.
- Anonymous2 months ago
Return the thermostat. Your system is not broken. Do not fix it.
- Spock (rhp)Lv 72 months ago
the manual for your hvac system has the hookup diagram you need for it and the Burnham manual the one for it -- too bad you didn't give us model numbers
- artherLv 52 months ago
is your system using the jumper between r and rc?
Is it currently supplied by the system power or just a battery?
would determine how to change it .
with loop removed
r is the power that comes for the heating unit transformer. switches to w when calling for heat
rc is the power that comes from the cooling unit transformer. swithes to y when cooling call, y2 2nd compressor..