Thermostat will not stop the boiler

[Boboule]

Hello I have a 2 wire installation for a boiler .when I plug one wire in W1 and the other in Rh the Nest works perfectly except when the desired Temperature is reached it keeps going..

if I decrease the temperature the boiler stops for 5 sec then restart…

do I have to add a wire?

thanks

[Ryan_G]

HI Boboule,

Thanks for reaching out and we're sorry for the delay.

This behavior of not turning off is also one of the indications that a C (common) wire is needed to help the thermostat stabilize its power. You could check for an unused wire or look for a wire from the main board of your HVAC.

I hope it helps.

Regards,

Ryan

[Boboule]

Thank you 

I added a 24v C wire adaptor and everything works great.

[Ryan_G]

Hey Boboule,

Thanks for the quick update! It's great to hear that it is up and running now because you already have it figured out. The c wire really is the answer and you've found it.

If you have any other concerns, let us know by creating a new thread and we'll be glad to assist you. This one will now be locked.

Best regards,

Ryan