Hot water not working at same time two weeks on trot, combi boiler, Nest

leeroyb

Hi,

I have a combi boiler and Nest which has been working fine since I first got it a few years ago. Last Saturday morning my heating was working but I couldn't get hot water. I was trying to get someone to come out to look at it but by late afternoon it was working fine again so didn't bother paying to get someone to come out and say it looks fine!

Everything has been fine all week but now again on a Saturday morning the water has again gone off whilst the CH is working. I'm hopeful it will come back on and doing all the resets on the system 'just in case' but the timing could be coincidence or something else.

I've called Nest and they confirmed they just send an 'all or nothing' command so it shouldn't be them, but asked them to look for any similar reports. If it was the boiler surely it wouldn't have come back or gone at the same time?

Any ideas?

Debbie_Savard

The Nest shouldn't have any control of the H/W in a combi.

It's more likely the flow sensor that detects water flowing to hot taps and fires the gas burner is faulty and needs changing.

It could be that it's happening on a Sat morning if mains water pressure is dropping down, more likely coincidence.

Alex1983

What boiler is it. Hot water always takes priority over central heating so I doubt it’s the nest. Does the hot water work with the heating off?

leeroyb

Hi Alex, yes it does work when the heating is off normally. It's an Ideal Esprit Eco 30

Alex1983

That’s very strange, I’d personally temporarily remove the nest and just replace with a link cable and see if it then works ok.

leeroyb

Yay plumbers. So no one will come out whilst it’s working, came back on Sunday eve. Everyone is on emergency rates at weekends when it may or may not happen again, and Ideal boilers looking at £290 minimum with no useful technical troubleshooting to narrow the problem in the first place.

Thoughts?

Alex1983

If it was off till Sunday evening I’m guessing your heating wasn’t on that whole time. I’d be very surprised if it has anything to do with the nest because the way a combi works. Hot water always takes priority.

leeroyb

The heating was on at different times throughout. The Nest only sends a heating on or off command, the boiler controls the water and/or heating

Alex1983

I’m a bit confused now, I don’t think it’s possible to be the nest causing it, but are you saying it only fails to provide hot water when the heating is on?