Help c wire

Jamie Hall

Actually, there are very good staples meant for low voltage wire -- they have a sort of a fancy half loop in the middle which the holds the wire(s). They take a special staple gun. And in the old days there were small nail in staples with an insulating pad under the staple which worked well too. The former simply can't cut the wire, and the old type is pretty hard to cut a wire with, too. Otherwise... yeah, common enough.

tedsalem

Amy looking for advice. I have to hook up my Nest and need the C wire which I don't have. Since I only have forced hot water heat, I only have a two wire deal. I can redo the wiring easily because the thermostat is in the basement near the furnace. I just need to attach a C wire to the Taco Zone Valve Control board. Much to my dismay, the board has only two contacts (R and W) for each zone. I attached a picture of the board. It seems to there are two 24V transformers connected to the 4 leads on the upper left of the board. To find the correct lead, can I do a continuity test between the red wire on zone 5 (thermostat) to see which of the 4 leads I can use as the COM?

tedsalem

I guess I can also check for 24V, but it must be live I guess

diego168

Hello everyone. It’s been 3 years since all you helped me with this wiring and it worked great. 

This week we were doing a mini kitchen remodel contractor removed a wall and needed to reposition one of my thermostats. Short story the contractor didn’t protect the wires and while manipulating across walls the red wire touched the white or C wired and burned my 75av transformer as we are having winter storm in the north east. I was able to find the problem fairly quick and had to check back on this thread because I had forgotten a lot of things. 

So my reason for this post is to thank everyone for all the help they gave me.