Nest thermostat Compatibility

[dantefasano]

Hi - I have a 3-zone forced air/AC system. My zones 2 and 3 seem fine for the NEST, W, Y and R wires.

My Zone 1 or main thermostat has W, Y, G O, Rc/R (jumpered), and B.

I am a little unsure how to hook this up to the NEST.

Also, I purchased the Nest Power Connector, I assume I need it.

Thanks,

Dan

[David_K]

Sometimes both the O and B wires are connected at the thermostat but the wires are not actually attached to anything at the other end on the system control board, so it's worth checking that.

Strictly speaking Nest Thermostats are not directly compatible with systems that need both O and B wires. It is possible to add a relay to resolve this, usually at a zone control panel, in order to make it compatible but for that, I'd recommend consulting professional help.

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