Heating/Boiler issue

[SlickShoes]

I am on the verge of paying someone to come and look at my boiler but thought I'd ask here just in case anyone has any ideas what is wrong with it:

I have a Modena 80E combi boiler.

When it turns on the burner lights and everything fires up fine, about 30 seconds later then burner goes out, the burner then comes back on again, then goes out after about 30 seconds. This process repeats until the heating/hot water is turned off. First time it happened was on a really windy day and I assumed it was the wind howling in the vent blowing it out, but I was clearly wrong. During all of this my radiators are still hot, my hot water is delivered, but the actual boiler is stuck in this cycle.

Oddly enough sometimes the boiler doesn't do what I said above and stays on for hours on end without the flame going out and then starting again.

If anyone has any ideas what it could be so that I don't get totally conned by a random company fixing it I would be eternally grateful!

[Future17]

It could be any number of things but that type of behaviour (i.e. the on/off situation) suggests a problem with either the fan or the air pressure switch to me.

If the fan itself looks OK, check the condition of the venturi (usually a small plastic tube with a narrowed section which is used to create a vacuum.

HOWEVER, to check these out you will have to be confident removing them and replacing them (with new ones if required). If you don't know what you're doing, get a professional.

The other problem is that if you remove the fan/venturi and it is damaged, you may not be able to refit it until you have a replacement. If your system is working just now, you might want to time your repair to coincide with a period of time when don't require warmth! :wink:

[SlickShoes]

Cheers for that! If it was summer I would probably venture in and have a look at it but as it's not freezing cold all the time in my house I guess I should just fork out the money and pay someone to fix it!