topic Re: No heating working but the hot water is working in Nest Thermostats

No heating working but the hot water is working

Btlizzard — Mon, 16 Oct 2023 09:02:08 GMT

Hi, I have a 3rd generation nest thermostat which had been working perfectly. We’ve had a lot of house renovations which plumbing and electrical work took place. The timer/schedule is now not working on heating but it does work on hot water. How can this be?

Re: No heating working but the hot water is working

MattyS73 — Mon, 16 Oct 2023 17:30:37 GMT

I have the same issue. Just noticed as the temperature has dropped. Works on manual if the hot water is on but not independently.

Re: No heating working but the hot water is working

Btlizzard — Mon, 16 Oct 2023 17:33:33 GMT

Correct :))) Anyone know why??

Re: No heating working but the hot water is working

LarisaL — Tue, 17 Oct 2023 17:40:32 GMT

Hi there @Btlizzard and @MattyS73! Thanks for reaching out. I'm so sorry to hear about this situation. Could you tell me if the boiler is firing up if you turn on the heating from the display, manually?

Re: No heating working but the hot water is working

Btlizzard — Tue, 17 Oct 2023 17:44:29 GMT

good evening, thank you for reaching out.
if I push the button on the Nest link (the white box with the big button) then that turns on the water and heating simultaneously. This is the only way I can get heating

Re: No heating working but the hot water is working

Btlizzard — Tue, 17 Oct 2023 17:45:36 GMT

So the answer to your question is ‘yes’ the boiler fires up

Re: No heating working but the hot water is working

AlexD — Wed, 18 Oct 2023 09:40:51 GMT

Thanks for letting us know here. I want to do some tests to see how the relays in the Heat Link behave. Go next to the Heat Link and open the Nest app on a mobile device:

1. Select your thermostat to access the heating controls and make sure the screen is black, heating is off.
2. Turn up the temperature until the display goes orange, heating on, and listen for a clicking noise.
3. Turn the temperature back down until the display is black again, heating off, and listen for a clicking noise again.

I also want to check for the hot water.

1. Go to the Nest app and select the hot water control.
2. Tap on the cogwheel in the upper right corner to go into the hot water settings and toggle the first option there off. This will turn off the hot water schedule, you can enable it back after the test.
3. Boost the hot water for any amount of time and listen for a clicking noise.
4. Turn the boost off and listen for a clicking noise again.

Keep us posted here with the results.

Re: No heating working but the hot water is working

AlexD — Wed, 18 Oct 2023 09:41:53 GMT

Hi @MattyS73 . Please try the same test I mentioned and let me know how it goes.

Re: No heating working but the hot water is working

Btlizzard — Wed, 18 Oct 2023 17:56:09 GMT

I did the test above for the heating, the heating when I turned the dial on the app made a click noise, but the boiler did not fire up nor did the orange appear on the app. The same with the heating.

Re: No heating working but the hot water is working

AlexD — Wed, 18 Oct 2023 17:59:00 GMT

Thanks for letting me know. Just to check did you also turn the temperature back down and checked for a clicking noise?

Also I assume for the second part you are referring to the hot water correct? As you mentioned heating again.

Could you take a screenshot of what did not go orange in the Nest app so I can have a look?

Re: No heating working but the hot water is working

Btlizzard — Wed, 18 Oct 2023 18:03:34 GMT

Beg your pardon I meant water. Yes, I turned down the temperature and the clicking noise occurred.
reference the photos, nothing turns orange

Re: No heating working but the hot water is working

TudorL — Thu, 19 Oct 2023 08:01:39 GMT

Thanks for letting me know. By any chance, do you have a system boiler with a separate water tank?

Re: No heating working but the hot water is working

Btlizzard — Thu, 19 Oct 2023 08:35:01 GMT

yes (it’s not a combi) with a separate water tank

Re: No heating working but the hot water is working

TudorL — Thu, 19 Oct 2023 08:41:28 GMT

This means that there is high probability that you either have an S plan or a Y plan, but I would incline that you have a Y plan, a 3-port valve, and when you activate the valve all the way, the heating is able to come on as well. I would recommend an installer to come and check the valve, but also the wiring that has been done on it.

Re: No heating working but the hot water is working

Btlizzard — Thu, 19 Oct 2023 08:44:32 GMT

I’m a Y plan, with a the port that acts as a safety for the hot water and a 3 port. I’ve actually got an electrician here right now

Re: No heating working but the hot water is working

TudorL — Thu, 19 Oct 2023 08:46:44 GMT

That's great, would he be able to check the valve now?

Re: No heating working but the hot water is working

Btlizzard — Thu, 19 Oct 2023 08:48:18 GMT

Both valves have been replaced last week.

Re: No heating working but the hot water is working

AlexD — Fri, 20 Oct 2023 16:19:40 GMT

Based on the fact that the Heat Link is clicking as expected that would indicate that the Heat Link is working as expected. Since you mentioned you had lots of work done on the system at the location it's most likely something in the system somewhere.

However if you want, I can send you the steps to perform a continuity test on the Heat Link. This will show for sure if something is going on with the Heat Link. If you have a multimeter and are comfortable in doing so, you can perform the test though it would be best to have a installer or electrician perform it, or a Nest Pro. They can also contact us live over the phone or chat when they are there and my colleagues can walk you through all the steps.

Re: No heating working but the hot water is working

Vladut — Mon, 23 Oct 2023 09:19:57 GMT

Hi there, just checking in with you. Did you manage to check the last message?

Re: No heating working but the hot water is working

Btlizzard — Mon, 23 Oct 2023 09:57:28 GMT

Hi, thank you for the tips. In the end up the electrician changed everything over but we never actually got to the bottom of what it was. Which is a shame as it’s always so useful to know.
however I think it could have been the tank stat, a lose wire perhaps.