Heating coming on at random times, don’t know where to start

[PureBlackVoid]

This may be confusing and long, sorry. I have a combi boiler, a couple of years old. It was serviced a few months ago. I have a separate freestanding thermostat. I keep it on manual so I can switch the heating on as and when I want it (having it on auto or a timer etc wouldn’t be useful as me and DP work odd shifts, I air rooms out at random times and it would be a pain changing the times every day to suit)

For the past few weeks I’ve noticed the radiators hot when I know I haven’t switched the heating on. As far as I can see they aren’t on for long before I notice it (based on Octopus half hourly readings). It’s also at random times in the day/night, as far as I can tell it happens only once in a day, but not every day.

It also used happen last year in spring. This was after we used the timer when we had more consistent shifts. After we stopped using the timer programme, and kept it on manual it started coming on randomly. When it happened last year, I played around with the thermostat and in the end the only thing that seemed to stop it was putting it on auto and putting required temp extremely low, below 10 degrees so the heating wouldn’t kick in, as it was toward the end of spring we knew we wouldn’t need the heating at all.

For the life of me I can’t find the manual, its been shoved somewhere during major refurbs but I remember the manual saying the heating would switch on if the temp falls below 5 degrees to avoid the pipes freezing. But the temp has never got to that level.

A side note - I think the thermostat may be showing the incorrect room temperature as it is, as at times it will say 13 degrees but I don’t feel that cold (I’m very cold usually, below 18 to me is freezing). I’ll be getting a room thermometer to compare but haven’t had time recently

When it was happening last year, I got in touch with the installer but he couldn’t find an issue. Because it obviously doesn’t happen consistently I can’t ‘show’ him what is happening, and it probably sounded like user error. I also can’t be sure that it has only happened at the times I’ve noticed it, whether it is happening more than once a day. It may well have been happening throughout summer but I spent most evenings in the garden when at home. and likely wouldn’t have noticed.

Could it be some sort of boiler self maintenance thing? Or some sort of comms issue between the boiler and the thermostat? I could leave it on to see whether it switches itself off after a certain time, but cost would be a concern.

Luckily so far it hasn’t cost us much, but I am forever paranoid that one day I’ll get home and the heating will have been on for 12 hours!

Is your boiler or thermostat somewhere that gets cold? Does the boiler has frost protection?

Our Nest thermostat ‘learns’ our heating patterns and then ‘helpfully’ puts the heating on at those times. It’s very annoying because we are very much random users at the moment. I have to go into the app and clear the programmed times that I didn’t ask it to program.

Is it a seven day or 5 plus weekend thermostat and does it have multiple daily time slots. I had this problem with one like this and working out how to clear all the slots was a pain in the neck and it consequently ended up coming on at odd times because somehow not all the time options were cleared. That was a thermostat that required pressing the button multiple times rather than a smart one.

Mine does this. It is so complicated. When setting up when we moved in it wanted us to pick a temperature for every hour.
So I put mine on manual as well.

but every so often it goes off. Even though I have it set to five degrees at night to stop that. . Woke up boiling the other night as it had turned itself on. Even though the gauge said 15.

Is it when you run the hot tap?

Has your neighbour got an identical wireless thermostat?

If you take the batteries out, does it stop happening?

Does it happen at cold frosty times?

When this happens to us it is always a stuck valve. What valves are there in your system? Sometimes tapping them will unstick them for a time but usually means replacing them.

Is it a wired thermostat or batteries? New or older model? Our thermostat started messing about like this when it had just got old and needed replacing. First thing to do is change the batteries (if uses them) if that has no effect change the box and the receiver on the boiler.

You've got a ghost!

Our nest does this too and I hate it!!

I can see how it would be useful but doesn’t work for us, especially as it doesn’t notify me that’s it’s done it! If it pinged my phone at least I could then turn it off remotely if I was out.

Re the nest, go into your settings and you can switch the auto learn option off.

I hope the op manages to solve their mystery too.

Sorry all, last time I checked there weren’t any replies!

I’ll try to answer all questions.

It’s a wireless battery powered thermostat, but a pretty basic one not smart, no phone connection etc. 7 day programme options, with multiple slots daily available to set but I cleared all the programmes last year when we didn’t need them anymore.

When it was happening last year, on a couple of occasions it did come on at the times they had been set to, after we stopped using the timer so I suspected something similar, like a communication issue. But this year it’s completely random.

Not just when hot water comes on. Immediate neighbours don’t have them, can’t be sure about the rest. I haven’t taken out the batteries to test it, it’s hard to test because there isn’t a pattern, different times, not every day. As far as I can tell it hasn’t happened since I posted this, but I have switched it on a bit more the last week.

Not just when it’s cold/frosty, it doesn’t seem to have happened when it’s been at its coldest so far this year. Plus last year it happened when it was fairly warm.

The boiler is in a cupboard in the kitchen, not particularly cold but there is an old small draughty window in there, not sure how much difference that could make. Thermostat is in the living room, it can get cold but this has happened sometimes when I’ve had the heating on a few hours earlier that day.

Both the boiler and thermostat are a couple of years old. I will change the batteries, I may have already tried that but my memory is failing me..

Next time it happens, is there anything I should check for, e.g on the boiler that could be out of the ordinary? I honestly don’t know what to look for, and how to tell if something is overriding the manual setting.

It's not a Salus, is it?

No, it’s a Center

Hi @PigletJohn I clicked the thread because my Salus is doing this exact thing! Can you explain why?

[Sorry OP to de-tour your thread! Can you find the manual for yours on Google, in case it sheds any light?]

Hit the little button top left to reset it to manual.

Usually.

Our heating was coming on at random points last year (getting the rooms up to 30 degrees even though our thermostat wasn’t set that high!), and it turned out the ironing board we had stored in our airing cupboard was leaning on the tank and sending it haywire. Anything like that that could be causing it?

this happens with our boiler when the timer unit batteries are on the way out.

as far as I can make out, the boiler default is to be ON all the time, and the timer unit manages when it should be OFF. So when the battery power in the timer is low, the timer stops talking to the boiler and so the boiler comes on at random times.

PS you should be able to google for the manuals

It's a make that is not highly thought of.

I switch my saleus off completely after every use (hold both buttons down for 5 seconds) would this help? They are such a pain.

When ours starts doing this it's usually that the batteries in the remote control need replacing.

Can you completely reset thermostat & change battery?
I found a YouTube video that helped me do mine step by step

Our thermostat inherited went kaput. Engineer brought a new one offers to activate the six settings. Noooooo I said just give us am and PM settings. I can always advance it. Things are too blooming complicated these days.

I had the exact same thing a year or so ago - radiators were randomly coming on despite the heating being set to off. I could even see the steam coming out of the pipe from the boiler so knew it was on!

After many calls with the boiler company (who seemed to be convinced I was a silly woman who *must have accidentally been using automatic modes instead of manual or was pressing the 'increase' temperature button instead of 'decrease'), they sent someone out and it was a faulty diverter valve. Luckily it's been fine since.