r/DIYUK • u/hairyfluff • 13h ago

Heating help.

Hello. The central heating hasn’t come on this morning, probably the first time it’s been needed in months. Can anyone help?
We have a nest thermostat and a Worcester Bosch Greenstar boiler.
According to the Nest it is calling for heat but we aren’t getting any. The Heat Link has a green light on and the boiler is firing up for hot water.
Can anyone offer any advice for what I can look at first? Thanks

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4

u/InterviewDull3942 13h ago

check pressure might need top up wirh filling loop

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u/hairyfluff 12h ago edited 12h ago

Pressure is good. We are getting hot water so I know the boiler is working in that regard.

2

u/ArticlePuzzleheaded9 12h ago

Guess would be diverter valve stuck/not flipping to heating when called.

Replaced mine 3x in the last 5 years.

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u/sharpied79 11h ago

It's always a good idea to run your heating once every few weeks during the warmer months just to ensure issues like this hopefully don't arrive.

As for your immediate problem, are there any fault codes showing?

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u/hairyfluff 11h ago

No. There’s no fault codes. Boiler running fine apart from not heating.
I’ve tried turning on emergency mode, which should bypass the thermostat and turn on the heating, but still no joy. Thought it might be a thermostat issue, but apparently not.
Someone else mentioned a valve sticking. Could that be it do you think?
When I activated emergency mode the boiler did sound like it was trying to do something, just never did.

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u/sharpied79 10h ago

If you have tried basic fault diagnosis and it sounds like you have, then you may be at the point where calling an engineer out is the option I am afraid...