Boiler firing intemittently

[DaveCalmore]

OK, so it's a 25+ year old Myson Orion and it started firing up intermittently a while back. It'll fire up and run then randomly there's a clonk and it goes out, only to fire up and start again. An Engineer came out, replaced the gas valve solenoids, decided it was the circuit board and quoted a crazy price to repair, so sent him on his way. Assuming his diagnosis was correct I ordered a refurbished circuit board, fitted it and it's doing exactly the same as it was before!

So, I have tested the room stat, the boiler stat and the fan and programmer and all are OK. The radiator pump is spinning too.

However, I have noticed that the boiler runs fine with the front cover removed, but not when refitted. (Front panel to the boiler, not the panel to the combustion chamber)

Can anyone tell me what this is likely to be? I wondered whether it's the air pressure switch near the fan? Otherwise could it be a leaky seal round the front panel? Gas valve itself?

 

[DaveCalmore]

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[rbranco]

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[DaveCalmore]

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[rbranco]

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[DaveCalmore]

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[rbranco]

So clearly removal of all the posts above even though (mine clearly stated what you are doing is not allowed and thus it was not advice but a clear warning which has now been removed) seems to indicate you should not be trying to fix this boiler yourself.

 

[DaveCalmore]

Sadly, whoever deleted it clearly doesn't know UK law...

"...you are legally allowed to service the boiler on your own. In fact, you are also free to service boilers in other households provided you do not charge them any money. If you charge money for your service, you need to be properly registered and licensed..."

In any event, all I was asking was what the fault was likely to be.

 

[rbranco]

Sadly, whoever deleted it clearly doesn't know UK law...

"...you are legally allowed to service the boiler on your own. In fact, you are also free to service boilers in other households provided you do not charge them any money. If you charge money for your service, you need to be properly registered and licensed..."

In any event, all I was asking was what the fault was likely to be.

It says you need to be gas safe or competent to do so, you need to be gassafe to work for money, but competent to work on your own system and competent is defined as if you have done relevant approved courses and have required tools, ie you could have a lapsed gassafe certificate or you did the training but not registered for gassafe. Problem is there are two sets of laws/rules, one states you can on your own system while the other defines competency requirement.

I can work on my boiler as the electrics to interface with ebus etc are external to the sealed box that contains the burner/valves etc, is a good feature of the Vaillant 418 but not all boilers have this and sometimes removing the front cover immediatly exposes the internals of the boiler and therefor becomes the issue.