Thermostat hot water programme

[SimonW1]

I have a Nest 3 thermostat. The boiler will not obey the schedule set out for hot water on the thermostat.

The central heating part works fine and the heating will come on in accordance with the set programme.

However, the hot water will not come on when scheduled to do so. At any other time it will come on, perfectly well and without problem but only if I select the ‘Boost’ command. During a time when the hot water is scheduled to be ‘on’ it will not be on and will not come on unless I also put the central heating on.

This is obviously very inconvenient and I would be glad if you let me know what you think the problem might be and how to remedy it. I have already tried a complete ‘Reset’ without any benefit.

Thank you.

[Frustratedddd]

Which system do you have, Ie - Combi or System Boiler?

When did you install the thermostat?

[SimonW1]

System. Thermostat installed December’22

[Frustratedddd]

OK, can you tell me which setting you have here.....click the water icon in the app - top right of the screen open settings [the cog icon] - what do you have On/Off set to?

[SimonW1]

It’s set to ‘On’. 

[SimonW1]

At least I’m assuming that the blue shows that it is switched on. The thermostat on the wall tells me that hot water heating is ‘ensbled’.

Thanks for your continuing help. Seems I have a problem with the program settings not activating the boiler for some weird reason while doing it manually works!!

[Frustratedddd]

That’s as it should be, and I assume the schedule is all set for hot water?

Has it ever worked since installation?

Do you have a motorised valve?

[SimonW1]

Yes, it worked fine until a few weeks ago and I’ve been trying to find out why since then. We have motorised valves and they are all working fine as is evidenced by the fact that I can get the boiler to come on to produce hot water using either the app or the wall thermostat whenever I want. But it still won’t obey the programmed instructions which are for 30 mins hot water both morning and evening. 🤔

[Frustratedddd]

Have you confirmed the valves are correctly working, as manual override does not prove they are. This has been talked about dozens of times on this forum.

[SimonW1]

Yes. My plumber has had a look at them and confirmed that they are working correctly. At the time the problem was sporadic but has now become persistent. 

[Frustratedddd]

Sounds very strange if everything has been checked correctly. Did the same plumber supply the thermostat and install, or who supplied and installed? Not a persons name, 

[SimonW1]

It was the same person who both supplied and installed the thermostat tho’ this wasn’t my usual plumber. Nonetheless, I have had every confidence that it was installed correctly, especially as it has been working perfectly well for the last 18 months since installation in December’22
The system that I have has been split so that I can control the temperature in the bedrooms upstairs separately to the central heating downstairs and hot water which are both controlled by the Nest thermostat. The heating upstairs is controlled by a Honeywell wireless thermostat. This has all worked perfectly well since installation in December’22. I can’t see that this setup should be causing a problem, really.

Should I try a reset of the Heat Link? 

Finally, may I thank you for your most helpful replies. It seems to me that maybe we have exhausted all possibilities other than a reset of the Heat Link which I’ll try tomorrow (as I haven’t really got time today).

[Frustratedddd]

My point wasn’t to state the install is incorrect or hasn’t been installed correctly! My point is, the supplier/retailer is still responsible for the thermostat. I would contact the installer as they supplied the thermostat, and ask them to come and check the issue. Should they find the problem, excellent, if not get them to replace the thermostat. 

You could reset the H/L, but that wouldn’t achieve anything as the H/ L is only a switching unit. You state the water operates in manual mode, which means the relays are switching.

The only solution you could try is a factory reset, but personally I would contact the installer and ask them to rectify.

I would also confirm the valves are working, as if sporadic, the they still could be the issue.

[SimonW1]

Thank you for all your replies. They have been most helpful. I’ve already tried a factory reset without benefit so I think it’s time to contact the installer as you suggest.

Many thanks and best wishes. 

[Frustratedddd · Accepted solution]

I hope you get the issue sorted, and please update us when rectified.

The installer might try to get out of repairing/replacing, but please remember, they are still responsible for your thermostat. Luckily in the UK we have consumer law, which means as they supplied and installed, they are responsible for at least 5 years!!

Good luck

[SimonW1]

The problem was indeed the motorised valve as you suspected. This has now been replaced and the system is working well again.

Thanks for your help.

[Frustratedddd]

Sadly not a surprise. I questioned so many times about the valves, I ask user’s every time check, then double check, and triple check the valves. Anyway all good now. Thanks for updating us here on the forum. Keep warm this winter!!!