I recently purchased 2 Nest Thermos for my 2 Zones. I have an oil boiler with the TACO SR-504-2 Zone Switching Relay.
Zone 2, first floor, is old construction. In order to get the Nest Thermo to work we needed the Google Power Connector.
Zone 1, second floor, had a green wire that we used for our comm wire.
Both are just R/W otherwise.
Zone 2, downstairs with power connector, set up through the app just fine. However, on the TACO Zone 2 never lights up, even when set to priority.
Zone 1 is hooked up with R/W/C however it gives does not recognize the wiring when trying to set up the device via the app.
The stranger thing is that the upstairs, with the unlinked Nest Thermo, is about 80 degrees. Zone 1 is illuminated on the TACO, unlike Zone 2, even without a connected Nest.
As a note I am not great with electrical but had an electrician friend assist with the setup. He's not familiar with Nest specifically, so couldn't really help me troubleshoot.
I can upload pictures if that helps!
