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upgrade to Nest termostat

PetroT
Community Member

Hello,   I have a Gas furness and Heatpump with Honeywell termostat. on my Termostat there is only three wires. how ever i have EMI which it has 8 wires . do you think there is way to by pass THM5421c ?

      Thanks

               Honeywhell Termo.jpg

 

 

6 REPLIES 6

Jhonleanmel
Community Specialist
Community Specialist

Hi PetroT,

Thanks for the photos and for posting.

Your wire label indicates an incompatible system.

These systems usually only work with thermostats made by the same manufacturer. But some incompatible systems may also have the option to use standard heating system wires. Contact a local pro and have them check if your system can be rewired to be Nest compatible.

Best,
Mel

Hey there PetroT,

Checking back in should you still have some questions here. Let us know by replying to this thread. 

Best, 
Mel

cbrd07
Community Member

Hello

I have the same setup as you. curious if you found any solutions. Difficult to find out what the wires are actually for. I am assuming the orange is for heat pump, white is for gas, yellow is for ac(yellow has two wires on mine, reversing valve?) , green is fan. 

Jake
Community Specialist
Community Specialist

Hey there,

 

If you are having trouble ensuring the wire functions, I would recommend checking your control board. I would also recommend having a HVAC pro come out, and ensure everything is set up properly.

 

Best regards,

Jake

Jhonleanmel
Community Specialist
Community Specialist

Hi folks,

Chiming in to see if you still need assistance with this. Let us know if you have additional questions ― we'd love to help.

Best,
Mel

Hi everyone,

Just one quick final check in here since activity has slowed down. We haven't heard from you in a while so we'll be locking this thread if there is no update after 24 hours. If you have any new questions, updates or just a discussion topic, feel free to start a new thread in the Community.

Thanks,
Mel