Nest Thermostat- What Am I Doing Wrong?!

[tb4122]

We have a Nest learning thermostat for our new central heating (we had useless night storage heaters before). Last night was the first time we've put the heating on and the Nest appears to be doing whatever the hell it wants!

I turned off learning mode so I could programme it to come on at 5pm if the temperature was under 18. Then I found it wasn't possible to set it to go off at a certain time, so I set it to the lowest (9 degrees) at 10:30. We went for a walk at lunchtime and came back to the heating on trying to heat to 18 degrees at 1pm and I have no idea why.

So now I've manually switched it off to stop it from switching on when it shouldn't and costing us money. Feels like it defeats the object somewhat to have to switch it on and off manually to prevent it randomly firing up the heating when I don't want it to. So far I'm really not liking it but DH loves a Google gadget so that's why we've got one... not that he can work out what it's playing at either

We have a nest I don’t use learning mode because I work shifts so it can’t predict correctly.

However I can schedule heating to come on and off which it does.I select a much lower temp (12 for example) on the schedule when I want it to switch off so it goes off. Never had any issues to be honest.

That's what I've done when I want it off and last night it worked- went off once it got to that time and the temperature never went that low to switch it on.

But why did it come on at some time between 12 and 1 this afternoon trying to heat to 18, when it's last instruction was 9 degrees? Even if it had dropped below 9 degrees while we were out (which I'm certain it wouldn't have done) it should have gone off again once 9 degrees was reached...?

Are you sure you turned learning mode off?

We tend not to programme ours. I just manually switch it on and off with my phone.

Yes, auto-schedule definitely off. Also turned off true radiant as I read that can help prevent it doing its own thing.

Did you set the date and clock correctly? Maybe it thought it was already 5pm, as it's clock is wrong, or you only programmed it for Saturday, not for Sunday?

If you set the heating to come on at 20 degrees at say 6am, I think the thermostat uses local weather reports and accumulated data to get the house to that temperature by 6am - not to actually switch on at this time. This could explain why it comes on at seemingly random times. If the thermostat learns that it takes 20 minutes to raise the temperature by a degree then it would switch on at 5.40am for example. I think the thermostat will say pre heating if it is doing this.

I can’t work mine at all. It just comes on when it likes.

Yep this is how it works and it's exactly why I stopped setting mine on the timer.

You can set it to pre-heat for a maximum of one hour only; it may have calculated it would take longer than that to get it to temperature at the time you wanted.

This is correct. Our heating was set to 19 degrees at 8am. It came on at 6.40 to get up to 19 degrees by then. The house was 17.5 so it reckoned it needed 1.5 hours for 1.5 degrees. If yours is new, it might not have worked out how long it takes to heat it or if your house was very cold, it might have taken 4 hours. Try putting it later or a lower temperature, as this is what it is aiming for.

Thanks for sharing that. I need this! We want some heating on in the morning but it drives me mad when it clicks on too early. But as the weather varies, the pre-heat time changes.

Ooo... pre heat for an hour would solve my morning issue. I just want to 'take the chill off' rather than have it click on at 3am to reach a certain temperature by 6am.

Yes, it works well for this! It’s in the True Radiant bit on Settings and default is 5 hours hence all the clanking at 3am if you don’t change it

My 40 year old storage heaters could never claim to be the most economical form of heating, but with input/output that only needs setting for the season, thermostats that limit charging if it’s unseasonably warm, the ability to have different settings for different rooms and a boost function for colder evenings (rarely used), they sound a great deal less hassle than your set-up.

Thanks @ReedOfFate, am going to be all over that when it gets cold enough to need the heating in the morning. It can't be that far off. 🥶

I turned off all of the learning features on our nest. I feel like all it learnt is that we like to have the heating on, so it just had it running 24/7.

Now I can see the history bit on the app for yesterday it does say "today's weather caused greater than average usage" so it must be taking info from elsewhere to make its decisions. I've turned off "true radiant" which seems to be the bit that decides how quickly it will take to get to temperature.

I think it's a bit too smart for me, I just want to tell it when to come on, how warm to be and when to go off again.

Same. I hate it.

Have you cleared all the programme data? This happened to me, I turned off the smart learning, but it still had programme data on it (I hadn’t programmed it), but it kept randomly switching on. I reset it and now it works fine.

@Firen no I haven't. Can I ask how you did it? I can't see a reset option on the app.

I'm just kind of following this as even though we've had it a year - it's still a bit random. Couldn't work out the learning bit...I think our lives our too random for that.

I'm coming to the conclusion that it's probably useful in learning mode if you have the heating on all day and tweak it up and down according to your comfort and then it learns what you like. I just want it to come on at a certain temperature in the evening and go off when we go to bed. I probably needed a much less smart gadget. I've dumbed it down as much as I can I think!

I despise our nest for all the same reasons you have mentioned. No idea how to set it to do what I want rather than what it wants!

I found it in the ‘schedule’ tab. I think it had programmed itself when it was in learning mode. I just deleted all the programmes. I remember doing mine on the device itself, you need to go to the schedule bit and clear it. You can probably do it in the app too. Mine only comes on when I want it now!

@Firen I'll have a look, thanks. That's all I want, for it to only come on when I want it to!

There is no way to get it to turn off at a certain time, is there? The best I can find it set the temperature as low as possible but the lowest I can go is 9. Considering it's reading 12 now I wonder whether it will keep trying to come on when it gets a little colder. I suppose I'll just have to manually turn it off if that's the case as I don't want it on.