Nest thermostat intermittently working

[lizmiluk]

Intermittently my heating isn't switching on. The Nest thermostat is orange as if it should be on, but it's not on and the boiler light isn't green.

If I then turn the thermostat up high, then click it off, then click it back on. Sometimes this works and sometimes it doesn't. It can take several attempts before it kicks in.

Ive checked the battery and it's 3..9V.

Thanks for your help.

[Frustratedddd]

Your system, is it UK with a Heat Link?

[DragosC]

Hi there @lizmiluk. Thanks for reaching out. Could you please share more details with me? What type of heating system do you have, where are you located and when did this issue start occurring at first?

[lizmiluk]

Thank you. I have a wocerster bosche boiler that heats the water (not a combo). I’m in Ayrshire, Scotland. It started a few weeks ago but we had to keep testing it at first as we were unsure it wasn’t actually turning on when the orange heating light was on but we now know it isn’t.

[AlexD]

Thank you for the information. Let us do a quick test to check how the internal relays behave. Go on the Nest app and go next to the Heat Link:

1. Make sure the display for the thermostat is black, heating off. Turn the temperature up until the screen goes orange, heating on, and listen for a clicking sound.

2. Turn down the temperature down, until the screen goes black, and listen for a clicking noise gain.

If you have hot water control then switch from the heating to the hot water control. Make sure that it is not scheduled to be on. If it is, go from the hot water screen into the settings by tapping on the cogwheel in the upper right corner and turn the first toggle there to off. You can turn it back on after.

3. Boost the hot water and listen for a clicking noise.

4. Turn the boost off and listen for the click noise again,

Let me know if you heard the clicks from the Heat Link when testing in each of these cases.

[lizmiluk]

Many thanks for your help. I have done all the steps and it clicks each time. Thanks.

[DragosC]

Thank you. Could you tell us please if the issue still persists? If it does, we'll need to perform a continuity test.

[lizmiluk]

many thanks for your help. We hit an engineer in to do a continuity test and it was found to be a zone valve that needed to be replaced. Thanks. Liz.

[DragosC]

Thanks for letting us know. That's great news. I'll have to close this thread. Should anything else come up, please open another thread and we'll take it from there. Have a good one and stay safe!