Nest Gen2 Won't Turn on Heat

[nestuser99]

We have two Gen2 Nest Thermostats in our home. Each one controls one gas forced air unit, one upstairs, one downstairs.

They have been installed and working for years without a problem.

Suddenly the downstairs unit will not turn the heater on. The thermostat shows "heating" but it does not actually heat.

If we put the downstairs thermostat in TEST mode, it WILL turn the heater on and will run for ~30 minutes and then shut off (because the test only runs that long).

After a couple of days of not working, it suddenly started working for a day and then stopped working again.

If we switch the two Nest locations (move the upstairs nest down and vice versa), the problem remains at the downstairs location.

We have reset the Nest. We have tried a USB charge. Both of these were suggestions on these forums, but because the downstairs Nest works just fine upstairs, we are at a loss to understand what's going on.

FWIW, the wiring shows that Y1 /yellow, G, Rc, W1 and C are all connected at both locations and again, it's been working for many many years without any issue.

Any suggestions would be deeply appreciated.

Thank you in advance!

[Patrick_Caezza]

If you swap the thermostats and the problem stays at the location, the problem is with the unit, not the thermostat.

Bring a service tech in and have them check out the system.

[straitshooter]

Howdy,

Just read your post.  If as you say, you switched one stat with another and the problem downstairs remains, you might have a system problem; not the stat.  In an emergency, (or as a test) you could bypass the thermostat by jumpering the connections and many posts on the web tell how it's done.

[Markjosephp]

Hello folks,

Thanks for the input, @Patrick_Caezza 

@straitshooter, thanks for reaching out and for your insight on bypassing the thermostat wires. We don't usually suggest bypassing it, as its improper configuration could cause a system issue. With this, it's best to reach out to an HVAC technician for inspection, as it was isolated by swapping the thermostats.

@nestuser99, I wanted to see if you still needed help. Have you had a chance to reach out to an HVAC technician? Please let us know if you have any other questions or concerns.
 

Regards,

Mark

[Markjosephp]

Hi there,

I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Regards,

Mark

[Markjosephp]

Hi folks,

I'm checking in to make sure that you've seen my response. Please let us know if you have any additional questions or concerns before I lock this thread in 24 hours.

Thanks,

Mark