navien ncb-250 and nest thermostat

[kho1112]

Hello All

I have a issue with nest thermostat with my navien ncb 250 combi boiler.

I Have 3 thermostat and i try it all. The boiler wont shut off with thermostat installed even it was off.

The boiler was shutoff when i pulled out the nest, I can be sure the wiring are correct.

The voltage between C and W are change between 19-27 with heat off. and C to R has approximate 3v.

[Jmli626]

Hi did you ever fix the issue? I just got a Navien boiler installed in my house. I’m having the same use as you. The Nest keeps on calling for heat even when it is off. 

[rk1988]

Same issue for me. 

Engineer ran cable to connect separate power connections through the CN25 and it's doing the same thing

[Rsalz7575]

I have the same issue with the same Navien, any one have a fix?

[Coreyc23]

Any solution here?