No Power to Rh but works with old thermostat

[Dkacz]

We have a boiler system. There are two wires only: Rh and W. We have window AC units. This shouldn’t be hard but for some reason when we tried to upgrade our Old thermostat to the new Nest one we kept getting an E74 error code then that stopped and worked for a brief minute so we turned on our heat and the boiler was working but the nest was not detecting it. We had to put our old thermostat back up. We had plenty of exposed wire. We tried reseating the wires three times. Help!

[CharlieChase222]

I’d like to bump this thread, I have the same problem.

[Jenelyn_O]

Hi folks,

Thanks for reaching out. Could you please share the photo of the wires connected to your Nest Thermostat? Also, try removing and inserting the wire connected to your RH terminal. Make sure that the breaker is off before touching the wires. 

Best,

Jenelyn

[Markjosephp]

Hello there,

I wanted to stop by and see how I could help.

@CharlieChase222, the thermostat or a particular wire may not receive enough power or any power at all from the system, which causes the thermostat to malfunction and display a report. Could you help us check your thermostat's power readings under the Technical Info option?

I'll look forward to your response.

Thanks for the assistance here, Jenelyn.

Regards,

Mark

[Dan_A]

Hey there,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Thanks,

Dan