GV1 – ZONE 1 VALVE
GV2 – ZONE 2 VALVE
Y1 – YELLOW WIRE 1
Y2 – YELLOW WIRE 2
R1 – RED WIRE 1
R2- RED WIRE 2
TT1 – ZONE 1 THERMOSTAT
TT2 – ZONE 2 THERMOSTAT
R RED WIRE
W WHITE WIRE
B BLUE WIRE
BOILER TX TRANSFORMER
R RED WIRE
B BLUE WIRE
G GREEN WIRE
W WHITE WIRE
We recently replaced old water boiler heater with new one(williamson) and I took the opportunity to fish new thermostat cable as well(replaced 2 conductor with 5). But my plumber is saying, I still can't use new Wi-Fi thermostat with it and it won't be efficient. I assuming that we wish to finish this job and move on to next one. So can someone please help me to find C wire for Honeywell thermostat. I have attached the current wiring picture with post. If you need any additional details please let me know.
Thanks in advance!
Here are few more pictures.
In picture you can see green and blue coming to gas control. Yellow is not used and looped back, while white and red is going to outside transformer which is in other side connected to emergency switch.
Can't upload anymore pics to the post. 🙁
Wiring harness from right side
TSTAT
DAMPER
Update#3
Boiler make and model
http://www.williamson-thermoflo.com/sites/default/files/field-file/gwa_manual.pdf
model GWA 175
Valve – Honeywell make
Best Answer
You might be in luck, but it depends on how the Honeywell thermostat works. I know Ecobee3 lets you power the thermostat using the
Rc
andC
terminals, but I'm not sure if Honeywell does the same. However, this solution might still work, even if the Honeywell is not the same as an EcoBee3.If you look at the documentation for the boiler, you'll see this.
Which shows that the boiler exposes additional wiring, that's intended specifically for powering a thermostat.
You can see these two wires in the photo of your boiler.
If the Honeywell can be powered using
Rc
andC
, then here's what you'll have to do.R
in the boiler (as highlighted above).C
in the boiler (as highlighted above).R
andRc
.R
wire in the boiler, to theRc
terminal on the thermostat base.C
wire in the boiler, to theC
terminal on the thermostat base.If the Honeywell thermostat cannot be powered using
Rc
andC
, then you may still be able to get it working. Follow the same procedure as above, but do not connect the wire between theR
wire in the boiler and theRc
terminal at the thermostat. Also, leave the jumper in place betweenR
andRc
. This may or may not work, depending on how the system is currently wired.