heatinghydronicnestthermostat-c-wire
I have a hydronic heating system (Lochnivar)that came controlled with an older (dumb)
thermostat. I have 5 wires behind the wall and 5 wire in the wire packet going into heating system however only the red and white wires are connected on both sides. The remaining wires (Yellow, Green, Blue) are not connected on either end.
I'm installing a smart thermostat that needs a C-wire, where can I connect that on the circuit board of my system (picture attached)? Any advice appreciated.
After looking closely at the images you've supplied, this is what it appears is going on in the last photo.
From what I know about HVAC systems, I would guess a broader view of the system would look something like this.
COOL call from the thermostat.C).When the thermostat calls for COOL, the BLUE wire is energized. This energizes the WHITE wire leading to the contactor, which pulls the contactor closed. The GREEN wire connects to the BROWN wire, which leads back to the transformer, thus completing the circuit.
Therefore, if you want to use the YELLOW wire as C. You should include it in the twist-on wire connector with the GREEN and BROWN wire.
You'll just want to make sure the transformer is sized properly to supply the additional current draw of the thermostat.
If it were me, I'd rewire it so that the YELLOW wire was the COOL call, and the BLUE wire was C. As that's a more common color coding.
Yes, tapping along with the red wire under the (C)OM is where it goes. If you'll notice, your (Y) is already double taped.
Best Answer
Nowhere in there. that's a DC circuit and a "C" wire is an AC thing.
you'll need to use an auxillary power supply to run your smart thermostat.