topic Boiler turns on unexpectedly in Nest Thermostats

Boiler turns on unexpectedly

charhep — Thu, 05 Oct 2023 12:56:48 GMT

Hi there

I was wondering if someone could help me please.

For a while now, my boiler starts up for a short period of time. I think max 5 minutes but it is difficult to tell as the boiler is outside. I think it happens at least 3 or 4 times of day but as it is outside, I am unable to see if there is a pattern. I have looked at the thermostat and it is not saying that the water is on. All a bit odd....

Re: Boiler turns on unexpectedly

Jenelyn_O — Sun, 08 Oct 2023 16:14:57 GMT

Hi charhep,

Thanks for reaching out. I'd like to know more about it. A few questions: what type of Nest Thermostat do you have? In what country are you located? Do you see any messages or codes on your thermostat or in the app? Please check your thermostat's Energy History. It will help you see what your thermostat is doing previously.

Best,

Jenelyn

Re: Boiler turns on unexpectedly

charhep — Sun, 08 Oct 2023 18:26:34 GMT

Thanks for coming back to me. I appreciate it. To answer your queries:

1) I am in the UK

2) it is a nest 3rd gen thermostat

3) No error codes are on the screen

4) Energy history is zero, haven't needed to put the heating on yet.

Look forward to your thoughts

Charlie

Re: Boiler turns on unexpectedly

Paul_R — Mon, 09 Oct 2023 16:10:24 GMT

Thanks for the details @charhep. I'm sorry to hear about your issue, but I'll do my best to help. When the boiler is starting, have you noticed a water droplet inside a yellow circle on the display?

Also, could you please go to Settings > Equipment > Bacteria Prevention, disable it, and then monitor to see if this behavior persists?

Re: Boiler turns on unexpectedly

charhep — Tue, 10 Oct 2023 14:46:04 GMT

Hi Paul, thanks so much for assisting. The boiler is outside so when I have noticed, I have rushed in to check & there is no water droplet in a yellow circle. Also bacteria prevention is disabled.

Thanks

Charlie

Re: Boiler turns on unexpectedly

AlexD — Wed, 11 Oct 2023 08:29:48 GMT

Thanks for checking. Just keep in mind that if you go to check the bacteria prevention and it says disable it's enabled it has to say enable, that it's disabled.

How long has the thermostat been installed for and working before you noticed this behaviour? Do you happen to have any separate programmers in the system?

Re: Boiler turns on unexpectedly

charhep — Wed, 11 Oct 2023 18:25:02 GMT

It was installed in January 22. I first noticed it in march of this year. I don't know if the problem is related to the hot water tank & towel rail. The towel rail always seems to be hot. Before it was only hot after the tank had come on which is twice a day.

Re: Boiler turns on unexpectedly

LarisaL — Tue, 17 Oct 2023 16:17:37 GMT

Hi there! Did you notice if there is a pattern to the boiler starting up?

Re: Boiler turns on unexpectedly

charhep — Wed, 18 Oct 2023 13:49:20 GMT

No not really - it's hard cos the boiler is outside so I can't see. Is there a way to access the thermostat to see if it has communicated with the boiler at all?

Re: Boiler turns on unexpectedly

AlexD — Wed, 18 Oct 2023 14:22:18 GMT

We can only check the heating history, we can't see any activation from the hot water side if that occurs. Do you happen to have any other programmers or thermostats in the system or on the boiler?

Re: Boiler turns on unexpectedly

charhep — Wed, 18 Oct 2023 14:29:35 GMT

I have a thermostat on my hot water tank

Re: Boiler turns on unexpectedly

AlexD — Wed, 18 Oct 2023 14:37:30 GMT

Most water tanks should have a thermostat, that is normal. Since you need to set a safe water temperature for the tank. Imagine if you put the hot water schedule on 24/7. If the water thank did not have a thermostat on it it would keep heating the water until it malfunctioned. That is why you my notice even if you have the water tank scheduled to be on all that that it is off, as the water temperature set on the thermostat on the tank is achieved and it deactivates the tank.

That is why there is no hot water history, as you could have the water scheduled to be on 24/7 but in reality the tank will turn itself off when the temperature on it is achieved and only turn back on one the temperature drops or hot water is used and fresh water fills the tank back up, cooling it down.

Let us try something next. Select the hot water control in the Nest app and tap in the upper right corner to go into settings. There make sure to toggle the first option you see there to off. This will disable the hot water schedule. We want to turn it off, just to check for a day, and see if this activation behaviour still happens with the schedule off. You can still boost the hot water should you wish to activate the tank to heat water.

Just keep an eye on it for a day and see if it still activates with the schedule off. If you do notice activating like before have a look on the display for any water drop marks and note if the heating is off or on at that moment.

Re: Boiler turns on unexpectedly

charhep — Wed, 18 Oct 2023 20:02:31 GMT

Ok - thanks for your help. Will keep you updated. Cheers

Re: Boiler turns on unexpectedly

TudorL — Thu, 19 Oct 2023 08:01:29 GMT

No worries at all. Keep me posted and stay safe in the meantime.

Re: Boiler turns on unexpectedly

charhep — Tue, 24 Oct 2023 12:43:07 GMT

Hi, yes boiler is still firing when heating is turned off. Thinking about it, I believe there is is a thermostat in our towel rail. It already seems to be warm. Do you think that could be the source of the problem?

Re: Boiler turns on unexpectedly

charhep — Tue, 24 Oct 2023 12:43:33 GMT

Sorry meant to say always warm!

Re: Boiler turns on unexpectedly

AlexD — Wed, 25 Oct 2023 07:58:27 GMT

It is possible. Additional thermostats or programmers could trigger the system.

Re: Boiler turns on unexpectedly

Vladut — Sat, 28 Oct 2023 08:07:03 GMT

Hi there, just checking in with you. Do you still need help?

Re: Boiler turns on unexpectedly

LarisaL — Mon, 30 Oct 2023 09:23:47 GMT

I haven't heard from you in a while so, if you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community. Thanks, Larisa.