Replacing Thermostat - need to add C Wire

Old 11-19-14, 03:58 PM
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Replacing Thermostat - need to add C Wire


I live in a condo with both floor heating (radiant) and I have a secondary unit that's both AC and Heat in one. It's York model.
The thermostat is hooked up to it and located on a wall in a hallway. Currently, the thermostat is showing 85 degrees (radiant heat in a hallway) but everywhere in a condo it's 70 degrees. I want to replace this thermostat with Honeywell YTH6320R1001/U where I can place a sensor in a different room thus making the temperature the same across my condo.
This thermostat requires a C-Wire. Here is what my current wiring look like.
From what I understand, I can buy a 5-wire thermostat wire from Home Depot and replace the current 4-wire system. Leave everything the same but only add the 5th wire to the "C" area on the relay (currently holding Big Yellow and Big Blue wires). Is that enough?

Wire from HomeDepot: Cerrowire 50 ft. 18/5 Solid Thermostat Wire - Brown-210-1005BR at The Home Depot
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Old 11-19-14, 04:33 PM
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Your plan looks good.
Is that enough what? Conductors?

I would get at least 6 conductor 18 gauge wire to have at least one spare wire, but 5 would work.

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