Thermostat always heating

[Maxlah]

Hello,

I just replaced my very old thermostat with the new Nest Learning 4.
This thermostat is connected to an electric furnace with 2 wires.
The problem is: The furnace will now always heat at full power even if I turn off the thermostat, the only way to stop is to turn off the electric switch.

The 2 wires are connected on the W1 and RH on the thermostat side and on “TH” and “TH” on the furnace side.

Can anyone please what could be wrong? Is my system compatible with the new thermostat?

Thank you,

Maxime

[SoriaD_]

Hello @Maxlah 

Thanks for reaching out to our Nest Community. Apologies for this situation with the heating system and your Nest Thermostat. Don't worry, I'm here to help you with that.

Just to confirm, according to your information, your thermosta has only 2 wires connected, and the system only works with heating. If not and your system has more wires connected, let me know.

In that case, to make sure about the compatibility, you can share with me the model for your furnace or a picture of the control panel of this. If you have a picture showing the previous wire configuration, that will be helpful.

Feel free to keep us posting. We'll find a solution for you.

Best regards,

Douglas.

[Maxlah]

Hi Douglas,

Thanks a lot for your answer,

Here are pictures of the old thermostat wiring as well as the wiring on the furnace side.
I also included the current wiring with the new nest thermostat.

Like you see it has only 2 wires that are connected to both of the "TH" label on the furnace.
I connect them to the RH and W1 on the thermostat, I tried swapping them but it gives the same result with the furnace always heating at full no matter what the temperature.

The furnace model is a Hydra24-E2401M-B.

I called google support and they told me my setup is not compatible with the nest thermostat but they would not say exactly why?
Any idea why that it?

Thank you

Maxime

[SoriaD_ · Accepted solution]

Hello @Maxlah 

Thanks for your response and the details you provided me. Let´s take a look.

I can certainly see that your system uses wiring that is not conventional to that compatible with our thermostats.This may complicate an accurate answer to the reason for this problem. This is because your system may be configured in a specific way.
That being said, I would recommend contacting a technician so they can diagnose your system and see if your heating can be configured in such a way that it can be controlled with your new thermostat.

If you do not have a technician, you can request one on this page: Get A Nest Pro.

I really appreciate your time and the details provided. I hope this situation can be resolved as soon as possible.

Best regards,
Douglas.

[Maxlah]

Hi Douglas,

Thanks a lot for your answer, I’m contacting a technician.

Have a good day

[SoriaD_]

Hi @Maxlah 

I´m happy to hear that. Don't hesitate to post us if you have more questions about this and your other Nest devices.

We hope you are well.

Douglas.