topic Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below in Nest Thermostats

Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

smayrand — Wed, 22 Jan 2025 15:02:27 GMT

Mi Google Nest Thermostat switch to aux electric heat if the outside temp is at -18 c (0 F) or below but my new heat pump can work at -28 c.

In the google apps, the lower setting to bloc the auxiliary heat can't be set below -18. Is there a way to set it to -28?

It'S seems to be a software limitation

Any ideas?

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

smayrand — Wed, 22 Jan 2025 19:34:20 GMT

I talked with the Google support and the Google nest thermostat (the cheap one puchased in 2020approx) do not allow to change the auxiliary temp setting below -18c. The support said that the New Google Nest learning thermostat gen 4 will probably allow to change that setting to -28 degree celcius.

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

gmelanymelissa — Sun, 26 Jan 2025 21:16:20 GMT

Hi @smayrand,

Thanks for posting in the community. I'm sorry to hear your Nest Thermostat switches to auxiliary electric heat if the temperature is at -18°C (0°F) and you're unable to adjust the auxiliary temperature setting below that point. I'm happy to help!

To better understand the situation, I'd like to ask a question:

It seems you have a Nest Thermostat (2020). Could you please confirm what type of Nest Thermostat you have?

Once I have that detail, I can assist you better with the specific information.

Keep me posted.

Regards,

Melany

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

smayrand — Sun, 26 Jan 2025 23:43:29 GMT

Hi Melany, yes it's the Nest Thermostat (2020).

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

gmelanymelissa — Tue, 28 Jan 2025 00:50:23 GMT

Hi there!

Thanks for the follow-up information.

Programmable Nes Thermostats often control auxiliary (AUX) heat in heat pumps using an "AUX lockout temperature." This setting determines when the heat pump switches from its primary heating method to a secondary, more powerful source like electric resistance heaters.

For example: If the AUX lockout temperature is set to 40°F (4.4°C), the heat pump will engage the AUX heat whenever the outdoor temperature drops below 40°F.

To adjust this setting in the Google Home app:

Select the desired thermostat.
Go to Settings > Equipment > Dual fuel breakpoint.
Adjust the temperature at which the AUX heat activates.

If your desired temperature isn't listed, it's likely unavailable. In the same menu, confirm the heat pump's orientation is set to "O" and that its heat configuration is correct. Visit our Help Center to learn more about Heat Pump Balance.

Keep me posted.

Regards,

Melany

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

smayrand — Mon, 10 Feb 2025 17:56:05 GMT

Yes the heat pump's orientation is set to "O". ... it just doesn't have enough temperature options available. It is why VAC guys hate working with Goggle Nest thermostat.

Re: Thermostat switch to aux electric heat if outside temp is -18 c (0 F) or below

gmelanymelissa — Tue, 11 Feb 2025 01:08:26 GMT

Hi there!

Thanks for the follow-up information.

Sometimes, it depends on the system if you can set it to more temperature options. However, to isolate the inconvenience, I'd suggest checking the following settings:

Check safety temperatures: Safety Temperatures can protect your home during extremely cold or hot weather. Refer to this article: Thermostat safety temperatures.

Keep me posted.

Regards,

Melany