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Another “rigging up a smart t-stat” post
I’ve got the most basic of basic: two wire heat only, old boiler with no board/panel. The system is powered from a 24vac transformer with the thermostat, LWCO, pressuretrol, and gas valve wired in series on the hot side.
I believe, because there isn’t constant power going to the thermostat (i.e., if the pressuretrol cuts out, so does power to the thermostat) I will need to add two wires (C for neutral and I think HC for hot). Is this correct? Can I simply tap each side from the transformer, or will I need a separate transformer?
Edit: Should the hot wire from the transformer go straight up to the thermostat? Should the safety switches be in series on the neutral (W) side, not the hot (RH) side?