24v thermostat to transformer/ZV - where does 3rd wire go?


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Old 12-13-13, 02:26 AM
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24v thermostat to transformer/ZV - where does 3rd wire go?

I'm installing several thermostats, transformers, and zone valves in a new propane boiler/hydronic baseboard system.

The wiring diagram ask for a third "common wire" if I want to eliminate batteries - something that would be preferred.

I cannot find diagrams that show connections at the zone valves/transformers with a 3rd wire from the thermostat. Where does it go?
 
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Old 12-13-13, 11:24 AM
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Referring to your diagram...
The black wire to your stat is R.
The yellow wire between the stat and valve is W.
The yellow wire between the valve and transformer is C.
C is your third wire.
 
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Old 12-13-13, 12:51 PM
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Thanks for the reply.

The diagram with yellow and red wires shows exactly 2 wires coming out of the thermostat - one black and one yellow. I have 3 wires coming out of each thermostat. Maybe I missed something on your explanation. Are you suggesting to add a wire in the diagram? If so, where?

Thanks.
 
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Old 12-13-13, 04:38 PM
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The transformer has 2 low voltage wires shown in your diagram.
One is 24 volt power (R) and the other is 24 volt common (C).
Connect your third wire to C at the stat and connect the other end to the common side of the transformer.

 
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Old 12-13-13, 05:18 PM
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Thanks so much! I can do that. Great help!
 
 

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