Turned CH on last night - now nothing works

[jimrat]

Hi
I have a Worcester 24SiII combi boiler. Hot water (HW) has been working fine all summer. Turned the Central Heating (CH) on last night - radiators warmed up, but Lockout light flashing on panel. Turned it off immediately. I read the manual in bed last night (yawn), and this morning reset the lockout, but now I get lockout for both HW and CH

The boiler fires up OK, and runs for a minute or two. Hot tap water or hot radiators, but then the flame dies. The boilers tries to relight (the electrodes spark), but no gas. Then there is a lockout alarm - flashing 4 times per second.

I have been through the fault finding stuff in the manual, and everything seems to check out:
HW/CH temperature sensors in place, not open circuit, correct resistance
Air pressure switch OK (including condensation in pipes)
Vent fan runs. Flue not blocked
CH pump runs OK

The only thing I've noticed is that the hot water seems hotter than normal. If the gas valve isn't modulating properly, could it cause these symptoms? When in CH mode, the flame intensity ramps up as described in the manual, so I don't know. Any ideas - hopefully not a new board!!

Thanks
Jim

 

[WDIK]

there you see? if you hadnt touched it you wouldnt be having to plead on here for help.

 

[Boilerman2]

Worcester boilers arn't that reliable then?

Sounds like something has failed, you should contact a local RGI to take a looky see

 

[Red_Man]

Could be overheating because of faulty thermistors.

 

[jimrat]

Jesus you guys are helpful

'Sounds like something has failed' No sh*t Sherlock! I've spent the day trying to get a heating engineer to answer their phone.

Plan B is for someone on this forum to say 'it's your thermistor' (thankyou Red_Man), then I go and test it, buy one, and fit it myself before my wife goes balistic.

Anyone else got an opinion on what's broke?