topic Not calling for heat in Nest Thermostats

Not calling for heat

Williamhaz — Sat, 16 Dec 2023 10:40:36 GMT

Our thermostat won’t call for heat. It was installed 2 years ago and has worked flawlessly. It dropped offline and since it went back online it has stopped calling for heat.

Re: Not calling for heat

jb76 — Sat, 16 Dec 2023 22:17:47 GMT

Hi - can you confirm the following from the Nest menu - if it is powered on, go to Technical -->Power and reply with the power output/charge for the thermostat? To communicate with the Nest (Wifi) and send control to your furnace, the Nest will need a 'Battery' level (shown in this menu) of 3.85 V or higher.

J

Re: Not calling for heat

Williamhaz — Sun, 17 Dec 2023 09:37:38 GMT

Yes the nest has power, as does the hub by the boiler. When I press the button on the hub it doesn’t turn on the heating either. The boiler is working well as hot water still is called from the taps. Maybe it is a hub fault.

Re: Not calling for heat

jb76 — Sun, 17 Dec 2023 18:01:52 GMT

Right - can you confirm the voltage/power going to the Nest Technical -->Power menu(power is critical for the Nest to operate properly - not just "turn on")?

J

Re: Not calling for heat

Williamhaz — Mon, 18 Dec 2023 17:37:31 GMT

Hi J,

Thank you for your help.

I am afraid I do not know how to do that. The nest was set up by a professional plumber and has worked perfectly for 2 years. It has just stopped after the firm ware update, it dropped off the wifi, is now back on the wifi and it appears that all has happened from this update is it has now broken.

Re: Not calling for heat

Williamhaz — Mon, 18 Dec 2023 17:42:39 GMT

Sorry so followed your instructions and battery is 3.912v

Re: Not calling for heat

jb76 — Mon, 18 Dec 2023 18:03:52 GMT

Hi - ok that voltage level is sufficient so if it is not calling for heat, there could be an issue with the control wire (W1) going to the boiler/heat control. I would recommend having a plumber/HVAC inspect this wiring and test controlling the system (manually) using that wire/connection without the Nest.

J

Re: Not calling for heat

zoeuvre — Mon, 18 Dec 2023 18:57:55 GMT

Hi folks,

Thanks for chiming in, @jb76.

@Williamhaz, yikes! I'm sorry to hear that your Nest Thermostat won't call for heat. Let's see what's going on. A few questions:

Are you located in North America or Europe?
What type of Nest Thermostat do you have?
Does the thermostat screen indicate that it’s actively calling for heating?
What type of furnace do you have? (gas, electric, etc.)
When did heating last work?
Did heating ever work with the Nest thermostat?
If not: Did the heating work with the previous thermostat?
Did you turn off the power to the HVAC system?
- Did you recently turn off any breakers?
- Have you recently experienced a brownout or blackout?
- Is there a light switch near the heater that controls an outlet?
Did you select the correct fuel type?
Do the LED lights blink on the HVAC control board? If yes, locate the light.
When was the last time you changed the furnace's air filter?
Have you experienced extremely cold weather lately?
Is this the first notable temperature drop of the year in the area?

Best,

Zoe

Re: Not calling for heat

Williamhaz — Mon, 18 Dec 2023 19:05:56 GMT

Hi Zoe,

Thank you for your in depth response, please see m response below:

Are you located in North America or Europe? Europe in the UK
What type of Nest Thermostat do you have? 3rd Gen learning
Does the thermostat screen indicate that it’s actively calling for heating? Yes
What type of furnace do you have? (gas, electric, etc.) Gas combo boiler
When did heating last work? Last week on Thursday
Did heating ever work with the Nest thermostat? Yes for 2 years
If not: Did the heating work with the previous thermostat?
Did you turn off the power to the HVAC system? N/A
- Did you recently turn off any breakers? No
- Have you recently experienced a brownout or blackout? No
- Is there a light switch near the heater that controls an outlet? Yes and it is on
Did you select the correct fuel type? Yes
Do the LED lights blink on the HVAC control board? If yes, locate the light. N/A
When was the last time you changed the furnace's air filter? Boiler recently serviced and the hot water works
Have you experienced extremely cold weather lately? Not extreme but it is winter
Is this the first notable temperature drop of the year in the area? No we have had the heating on since November

Re: Not calling for heat

TudorL — Wed, 20 Dec 2023 09:58:18 GMT

Thanks for all the info provided. Is there any LED light on the Heat Link at this moment and if yes, what's the color?

Re: Not calling for heat

Vladut — Fri, 22 Dec 2023 16:16:49 GMT

Hi there, just checking in with you. Did you manage to check the last message?