Occasional loud bang in boiler

[dominoman]

My old boiler (Potterton Suprima 50) has been pretty good and reliable.

However last weekend when I was next to it it gave a massive bang noise. I turned it off and left it.

I had it serviced and the man said it was all fine.

The next day I turned it on again, and it was fine until today when it did the same thing. This time I ignored it and it is still running now.

Any idea what is wrong? Is it dangerous?

 

[ScottishGasMan]

If its a single bang with no other noise, then its likley to be "hard ignition" where by it releases gas to be lit, but either not enought/too much or the spark plug taking to long to get it lit, and it lights with a bang.

Is it an old suprima or a condensing suprima?

 

[Agile]

Just in case, look down the inner flue pipe from the outside with a torch and see if there is any corrosion or holes evident.

Should really be checked when serviced but many don't bother!

Tony

 

[dominoman]

If its a single bang with no other noise, then its likley to be "hard ignition" where by it releases gas to be lit, but either not enought/too much or the spark plug taking to long to get it lit, and it lights with a bang.

Is it an old suprima or a condensing suprima?

It's an old suprima (not condensing). Seems to work OK apart from this.

The service didn't show any problems, though given how quickly he was in and out I don't think he really did any more than a gas safety test

 

[Dan Robinson]

Two things spring to mind.... well maybe three.

One should have been obvious on the service, the other not so much.

If it is the "maybe" then that would have been fairly obvious on the service.

I think a single thread is sufficient for this though dude. And the items on my mind are not for the open forum.

 

[dominoman]

Two things spring to mind.... well maybe three.

One should have been obvious on the service, the other not so much.

If it is the "maybe" then that would have been fairly obvious on the service.

I think a single thread is sufficient for this though dude. And the items on my mind are not for the open forum.

Yes - sorry about the two threads. Initially they were on two very different topics (the other one was about what to expect in a service).

The man who did the service is now coming back to replace the ignition contacts. Hopefully that will do it.

Personally I'd have preferred he just cleaned them with solvent first, which is what it says to do in the service manual, but he says he is reluctant to do that given the age of the boiler.

 

[Agile]

I cannot think of anything to clean with solvent in a Suprima.

Did you look into the flue as I described?

Tony

 

[Agile]

The service didn't show any problems, though given how quickly he was in and out I don't think he really did any more than a gas safety test

After all your questions about what is in a service, you don't seem to have noticed what he did or even questioned why he may not have done all the things which we told you about!

At the very least he should have opened the combustion chamber!

The poor ignition is often caused by problems in the ignition lead. They have a carbon film inner for TV interference suppression and the pins at each end often don't make good contact with the carbon. If you know how they can be repaired but most just replace them.

Tony Glazier

 

[dominoman]

I cannot think of anything to clean with solvent in a Suprima.

Did you look into the flue as I described?

Tony

No - not yet. I will do it tonight. Thanks for your help