'Explosive' Boiler Lighting

[JohnT38]

Hi,

Potterton Suprima 100 boiler; about 10-15 years old.

Generally works OK, but sometimes re-ignites, immediately after a burn, with a loud 'explosion' - sometimes with enough force to knock the fridge magnets off the boiler casing.

The boiler is serviced by British Gas engineers; and they have additionally been called-out on a number of occasions over the past couple of years and they have found nothing wrong, nor recognised this as being a problem!

Any opinions or advice, greatly received!

Many thanks,

John

 

[Boilerman2]

This sounds like the burner is flashing back to the injector on shut down,
this is usually attributable to a faulty gas control valve not shutting down cleanly, the flame flashes back through the burner back to the gas injector, with a pronounced "Bang", get BG to check the effectiveness of the gas control valve and replace if necessary

 

[JohnT38]

Thank you Boilerman2 - greatly appreciated.

We'll give BG a call and see what happens...

John

 

[Agile]

I met one where part of the insulation panel had broken and fallen across the burner.

 

[JohnT38]

I met one where part of the insulation panel had broken and fallen across the burner.

Many thanks; but hopefully not in this case - you would hope BG would have noticed, if that had happened here

 

[Agile]

They would only notice that if they opened the combustion area and looked inside!

Why have you put fridge magnets on the boiler? Perhaps it will cure the problem if you put them back on the fridge where they belong!

 

[gaswizzard]

Maybe some stronger fridge magnets?

 

[gaswizzard]

Burner will be more than likely seperated between mixing tube and burner head , common problem on these.

 

[JohnT38]

Maybe some stronger fridge magnets?

Problem is: the fridge is built-in, so has wooden door...

Might cause fridge to explode?

 

[Tibbot]

I met one where part of the insulation panel had broken and fallen across the burner.

Agile's explanation above is the most likely cause. It's also the easiest for a engineer to check. Easily cured as well if that's what it is.

 

[Boilerman2]

As B.G. have been to look at the explosive boiler on more than one occasion, you would hope that they would have found such a simple fault

 

[JohnT38]

Many thanks to all who have responded so-far.

One further observation... as I said, the 'explosion' happens when the boiler re-ignites immediately after a long burn - but this 'second burn' only lasts for 10-15 seconds and then shuts-down. Can't be right, surely?

 

[tarquindemeza]

this is caused as a result of a fault / failure with the burner. Directly below the burner are two tubes which for some reason are not welded to th gas burner assembly. The explosive sound is caused by a leakage of gas around the base of the tube joint or a hairline crack in the tube where the gas escapes & lights later causing the explosion. The part costs circa £140+ vat so is an expensive part but labour should not be dear as it only takes 5 - 10 mins to replace. Alternatively the part can be repaired using a Fire retardant joint sealing compound such as Holts "Firegum" which is designed for use on car engines, exhausts , gas fittings etc & is designed to withstand temps of 1200 C. Should be used liberally around joints or cracksc. It sets very quickly & under heat hardens & seals more tightly! You should also replace insulation & fully clean heat exchanger. This will 100% guarantee stop the explosive sound inside!

 

[45yearsagasman]

this is caused as a result of a fault / failure with the burner. Directly below the burner are two tubes which for some reason are not welded to th gas burner assembly. The explosive sound is caused by a leakage of gas around the base of the tube joint or a hairline crack in the tube where the gas escapes & lights later causing the explosion. The part costs circa £140+ vat so is an expensive part but labour should not be dear as it only takes 5 - 10 mins to replace. Alternatively the part can be repaired using a Fire retardant joint sealing compound such as Holts "Firegum" which is designed for use on car engines, exhausts , gas fittings etc & is designed to withstand temps of 1200 C. Should be used liberally around joints or cracksc. It sets very quickly & under heat hardens & seals more tightly! You should also replace insulation & fully clean heat exchanger. This will 100% guarantee stop the explosive sound inside!

What are you on about? What 2 tubes? Advocating Holts Firegum on a gas boiler.

 

[Dan Robinson]

nimrod.

That is all.