Alpha 240E combination boiler problem

[superseven]

I have a really weird problem with the above boiler.

When you select either hot water only or with central heating, and turn a hot tap on, the boiler will fire up as normal for a minute or two, then suddenly shut off.

If you then turn the hot water tap off the boiler will randomly come on of its own free will even when the heating is selected off and switched off, and the room stat is turned right down.

With the heating selected on you can get the boiler to come on and off with the roomstat, sometimes by going below the room temperature and sometimes by going above it, but again this seems to be entirely random.

I have gone through the troubleshooting in the manual, and it seems to point to the fan, but this does'nt make sense because if it was the fan then surely the boiler would'nt come on and run of its own free will.

I'd appreciate any ideas,

thanks

 

[gas4you]

When the boiler comes on for its 2 minutes on HW do you get the top orange light come on as it goes off?

 

[superseven]

No, it just goes off. The orange light for the fan flickers on then straight off before the boiler fires up initially, but I don't know if this is part of the pre test procedure to allow the boiler to ignite or not?

 

[gas4you]

Yes that is normal for the orange light. It stays lit for a second or 2 whilst the aps proves the fan.

From this then it does not appear to be a fan or aps related fault.

I'll give it some more thought.

 

[superseven]

ok thanks for your help. I had a word with a friend of a friend who is a Central heating engineer, and he said it sounds like the diverter valve?