Vokera HE Compact- Only fires when the front cover is off

[ARWadworth]

My friend has a Vokera Compact HE combi boiler.

When HW or CH is called for the boiler starts to make its normal firing up noises (I assume it is the fan) but never actually fires. There is no ignition sequence or spark.

I took the cover plate off the burner front to have a look at the spark and with this cover off the boiler fires. Replace the cover and the boiler stops burning. The fan stays running.

The flue is clear of any debris and I changed the air pressure switch and checked the tubes for damage. No change.

I realise that the boiler fires with this cover off as air is getting into the burning chamber through the front and not through the flue.

So where do I look next to find the fault?

Adam

[cynic]

Is there an obstruction inside the flue where the sensing tubes enter the airstream? This could be down to corrosion within the venturi. Alternatively leaves or cobwebs obscuring the air inlet or flue outlet. (Other causes not discounted)

[Cicero]

================================== A remote possibility...

My boiler gave the same symptoms for a quite simple fault. The boiler would only fire up with front cover removed and it did this consistently. Every time the cover was replaced it failed to fire up. When I removed the cover to try again I noticed that the small ignition lead was sparking against the boiler chassis and no spark was reaching the correct ignition point. The ignition lead was being partly trapped when the cover was replaced. The strange thing is that the insulation on the ignition lead appeared to have broken down spontaneously - no physical damage visible. In my case the lead was able to spark normally until it was pushed against the chassis, so you might try moving your ignition lead about to see if it does the same.

Cic.

[Sukhdev]

replying to ARWadworth, Sukhdev wrote: clean the venturi on the fan.

[alan_m]

I don't think he wants to know now - 9 years after he posted the question.

Hint: the web portal you are using likes to promote questions from a decade ago as a current topic.

[Brian Gaff]

Yes its a bloody mess and they have been told what a heap of crap their interface is. I'm not totally sure if they even care. After all they pass this place off as theirs, when it is clearly a Usenet group and these have been around for longer than the web has. If anyone wants to use it legitimately first try to figure out if the post is very old if possible then quote part of it in your reply, at least that way people here will know what its about. Nobody is going to go on that web site to fiddle with the interface to do what they can do perfectly well with software meant for the job of using the newsgroups. Brian

[Fredxxx]

This might assist you with posting to a newsgroup, albeit through a website:

- If you are sending a reply to a message or a posting be sure you summarize the original at the top of the message, or include just enough text of the original to give a context.

[Anthony Savill]

replying to ARWadworth, Anthony Savill wrote: Hi did you find the problem with your boiler as i have the same problem thanks

[alan_m]

Check the date of the post you to which you are replying. It's 10 years ago!