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Replacing Honeywell T10 Pro with Nest Learning. Standard a/c and separate whole home Dehumidifier

Community Member

I recently moved to a new home and want to replace the existing honeywell thermostat with Nest. I have tried using the wiring compatibility tool with Google but there is no U1 and U2 wire equivalent to the honeywell thermostat. I'd like to DIY this but not sure if I can.  from what I can tell, it looks like:

  • U1 (cyan) is connected to the white wire (DHUM compressor + fan on the dehumidifier)
  • U2 (brown) is connected to the red wire (R on the dehumidifier) 

I have attached some images of the wiring on the wall, the a/c circuit board, and the dehumidifier circuit output

I'd appreciate any help or advice!




wiring diagramwiring diagramwiring diagram (different angle)wiring diagram (different angle)wiring out of dehumidifierwiring out of dehumidifierdehumidifier modeldehumidifier modelwiring at a/c unitwiring at a/c unit


Community Member

and the nest wiring for referenceand the nest wiring for reference

Community Specialist
Community Specialist

Hi b21morales, 


Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Fortunately, your thermostat wires are compatible with our Nest Learning Thermostat 3rd generation however, since your system has a dehumidifier wire, or more than one dehumidifier wire, you need a local HVAC professional installation to maintain the proper relative humidity. You can learn more about this by checking this article of identifying a thermostat wire


Reach out if you have any questions in the future.