Installation of a c wire

mograteful

I am using a taco SR 501 switching relay for my three zone propane, gas furnace. I have the basic thermostats now just use a red and white wire. I want to add a setback thermostat that requires a c wire. The switching relay has a 24 V AC common. My thermostats are not directly connected to the TT terminals. How can I use the c wire or do I need to connect a separate 24v transformer between my c wire and my red wire going to the thermostat 

Zman

Do you have zone valves or zone pumps?
With zone pumps the SR-503-4 would be appropriate.
With zone valves the ZVC-403-4 Would be best.
I don’t understand how you intend to use a single zone pump relay to run 3 zones. The transformer is not sized for that.

mograteful

I agree with you 100%. The system in my mind was putting incorrectly but then again I’m not an expert. I bought a 24 V transformer. I solved the problem with that. I just thought that I could use the one that was on the Taco, thank you 

EdTheHeaterMan

@mograteful, we need to get back to basics. What is the thermostat that you want to replace connected to? Since you have 3 zones I assume you have three thermostats. each of those thermostats has a wire connected to the W terminal on the thermostat. The other end of that wire is connected to __________?

I feel like Gene Rayburn with that last question.

Joe Mattiello

you can use the com terminal located on SR control. there are a couple Rev existing, so I cannot be specific, however, you can reach out to Taco tech support at 401-942-8000 for support. have the complete model number available when you call.