Just installed a brand new gas boiler, want to keep using my existing Nest thermostat (they are compatible according to Nest).
- Current system only has two wires: Rh and W
Nest is designed to steal current from Rh to charge, but here is my problem: the potential between Rh and W is only 22V, and the Nest requires at least 24V. I get a no power reading on the thermostat.
I know I can add a switching relay, as the furnace instructions state – but here's my idea and I hope somebody can tell me if this would work or not (I don't want to damage anything):
The potential between Rh and ground is about 24V; there is about 1.5V on the W wire. Could I simply run a C wire and connect it to ground (or the the C terminal on the transformer inside the boiler)? Or do I really need to spring for a switching relay.
Attaching the schematic from the manual on connecting thermostat.