Nest heating system, hot water not firing up

DXR

Hello everyone.

We got a nest thermostat fitted a few years ago, and it's always worked perfect up until now. Lately though the water isn't heating up (for showers etc) using the app/manually using the thermostat, however if I set the home heating to come on the gas boiler fires up.

My very limited research pointed me up towards the hot press, found the two different boxes with switches on them, one clicks (the radiator one) when activated, the other one does not. I was speaking with a guy who knows a bit about these and he told me there's a manual switch/lever on these boxes, and if I push the lever to one side the water heating should activate, however it would not come off again, until I go back up and switch it the opposite way again, however moving the lever does nothing, meaning the gas boiler doesn't fire up doing this either.

I have had to start using my immersion heater for water since this started happening a few weeks ago.

So my question would be, do I call out a plumber, an electrician, or someone who installs the nest thermostat systems?

Any help and advice really appreciated.

Wearb

Temporarily, if you move that manual lever to on and switch the heating to on (make sure thermostat is turned up enough to call for heat) it should heat your hot water. You can turn off each rad for now.

Then arrange for a plumber to check it out. Most likely that hotwater zone valve is faulty.

DXR

https://www.boards.ie/discussion/comment/122375065#Comment_122375065

Hello,

Yeah I did try that a few weeks ago (I've just returned from holidays) unsure if I had the thermostat turned up though, so I'll try that and report back

Thanks for your advice

DXR

https://www.boards.ie/discussion/comment/122375065#Comment_122375065

I turned the boost feature on and manually moved that lever and nothing happened, no "click" and no red light on the box either, nothing from the gas boiler either, so I'm assuming it's goosed.

Plumber job?

Wearb

Did you turn on the heating ie heat for radiators?

DXR

https://www.boards.ie/discussion/comment/122375214#Comment_122375214

The radiators are working fine, it just seems to be the hot water that nest won't control.

Hope this makes sense

Wearb

Yes. But you need to carefully read my suggestion. Turn on the lever on the non working zone valve. Then go to your controls and turn on your house heating for at least half an hour. Make sure your boiler is running during that time. Also check that the lever on the non working valve remains in the on position during all of this.

DXR

https://www.boards.ie/discussion/comment/122375722#Comment_122375722

Ah, got you now!

DXR

Update, got an electrician in who tested various cables, there's some kind of switch needed, he says it's not calling for the gas boiler to activate when I ask for the hot water to be boosted/scheduled to come on.

He'll pick up one this week, reckons it's a very small job.

Thanks for your help.

Wearb

Keep us updated. You might have be lucky enough to get an electrician who'll just replace the micro switch.

Time wise (taking callout and hourly rates into account) it's often just as cheap to replace the whole unit.

DXR

https://www.boards.ie/discussion/comment/122390809#Comment_122390809

I will do, guy is a neighbour and friend, so hopefully I'm looking at less than€100 but will keep you updated

DXR

https://www.boards.ie/discussion/comment/122392468#Comment_122392468

It's a thermostat by the looks of things, this is what he pointed at anyway.

Can see from googling, not an expensive part, so hopefully, please be to god, this will sort it 🙏🏾

Wearb

Oh! I was thinking zone valve.