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Nest doesnt work but old thermostat does.

Fallout556
Community Member

The Nest thermostat was detecting a problem with the W wire and giving an E102 error. I checked the wire at both ends, redid the connections, and tried a different base plate and thermostat but continued to receive the same error. Out of frustration I reinstalled the old thermostat and it works just fine. 

I have two identical systems, one for the first floor and one for the second. The nest on the first floor is working fine. 

 

I've checked wiring at both ends and have considered running a new line, but if there was a problem with the line I don't think the old thermostat would work. 

 

Any suggestions before I have to bring in a pro?

 

UPDATE - 12/14/2021

I had a professional rerun the thermostat wire and try installing a nest thermostat  and it still had the same issue. He was not sure what the issue was as all the wiring was fine. 

 

I've tried three different nests including a brand new one and they all say there is an issue with the white wire and do not heat, but the old thermostat does. 

 

Does anyone have potential suggestions?

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