Need Help to Install Nest Thermostat - Compatibility

[jhaz]

The compatibility checker said my system may be compatible. The installation app says it's not. I have an original hot water boiler for heat and an added later central a/c system. I have the old thermostat with wires on the terminals labeled W, RH, RC, G and Y. It looks like there are two cables coming into the thermostat. There are no jumper wires. Can someone please advise if in fact the Nest thermostat will work with my system and what I need to do to install it?

[Jenelyn_O]

Hi jhaz,

Thanks for reaching out. I'm sorry for the delay. I'd like to take a closer look at it. Could you please take a photo of the wires connected to your system's control board? Ensure that the labels of the wires are visible. It will help us to further check your system's wiring configuration to the Nest Thermostats.

Best,

Jenelyn

[jhaz]

[Jenelyn_O]

Hey jhaz,

Thanks for posting the photo of your thermostat wires. It looks like you have a separate power wire for your heating and cooling. For dual transformers like this, the Nest Learning Thermostat is the one compatible with your system since it has two power terminals unlike Nest Thermostat E and Nest Thermostat 2020. 

If you have a voltmeter and you're comfortable using it, I suggest checking how much power is running to the wire connected to the RH terminal. It will help us to ensure that it is a power wire and not a jumper wire.

Please keep me posted.

Regards,

Jenelyn