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XMNest · 01-25-2022

I have a mercury thermostat with 3 wires (R, G and W) thermostat control. Between the R & W wires, I tested 24V AC. The Aquastat relay for the boiler is L8148 E 1257 and I want to replace my old thermostat with a Google Nest Thermostat (G4CVZ). I wou...

XMNest · 02-02-2022

Sorry my mistakes, the third wiring method should be as following: 3. I measured a 24v AC between my G and W, so I wired like as follows, Nest seems works but can't control my boiler (my boiler always heats up whether the Nest is “heating” or not): R...

XMNest · 02-02-2022

Hi Ryan, Thanks for replying to my question about the Nest G4CVZ, maybe the 3 wires system is not suitable for the Nest GrCVZ thermostat. All details and photos are attached in a PDF file (I don't know how to insert photo and PDF firl here, so I will...

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Nest G4CVZ wiring issue (replace old mercury thermostat with 3 wires for boiler)

Re: Nest G4CVZ wiring issue (replace old mercury thermostat with 3 wires for boiler)

Re: Nest G4CVZ wiring issue (replace old mercury thermostat with 3 wires for boiler)