Electrical – Install Common Wire (unable to find terminal or 24 VAC)

electricalfurnacehvacthermostatthermostat-c-wire

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I bought a Nest 3rd Generation Thermostat. Live in a 2 family home, where my floor/basement has the boiler room/furnace. I have a Laars Mini Therm Furnace Model JVT. There's a thermostat upstairs as well, where both control / call for heat when needed. For some reason, my Nest is never receiving Rh power (I checked with voltage meter and shows 24 VAC). I've read countless articles on this site and elsewhere and it seems a Common Wire would help alleviate this however I can't find where to run the Common Wire myself. Not a pro, but I've messed with this furnace for hours this whole week and practically know it but no cigar yet. Can anybody help?

I've attached pictures. I think it goes on the A? terminal however there's no voltage detected there (I once saw 12 VAC btu not sure if it was a fluke)

Thanks everyone [![Terminal Board[][1\
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Best Answer

Currently according to the wire diagram the wire on the R terminal comes straight from the transformer. The C wire should be the other leg from the transformer. So you need to add a wire branched off from one of the Y wires and run it to the NEST thermostat.

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