Explosive Ignition

4 Jun 2008
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United Kingdom
Can someone please explain exactly what causes Explosive Ignition, ie in a gas boiler, and what eactly it means? I am curious and am trying to find out (but searching the net or this site hasn't helped). I am guessing it is when a burner fires up loudly, due to possibly too high gas pressure or too high a gas rate, ie injectors enlarged/oversized?
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I get your drift, thanks for the picture. I was meaning on a less severe scale, ie in a domestic boiler. Just wondered what causes it and what the initial signs would be.
An explosion normally requires a very low concentration of gas. In a boiler the gas concentration is much higher.

I would have thought low (very) gas pressure or lots of blocked jets would be the most likely cause.
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sometimes high gas rates can cause an explosive ignition. especially in water heaters, hence why they have slow ignition devices inside them, to allow the gas to be lit by the pilot smoothly...

i'm not sure about boilers though.
its a gas related question, which shouldnt be discussed in public.
remember it wasnt curiosity that killed the cat it was exlosve ignition ;)

ps the causes are numerous
I know its a gas related question, I was just wanting to know what caused it though. I know about burner pressure/gas rate checking/injectors etc I was just trying to understand why it could happen!!!
When to do with actual boiler as opposed to supply problems.

On permenant pilot models it is usually caused by a dirty pilot assembly which makes pilot too small and does not catch gas coming out main burner quick enough.

On auto ignition boilers it is weak spark caused by wrongly position electrode/damaged electrode/damaged lead or wrongly adjusted gas pressure.
Can also be a faulty gas valve passing gas when it should not then when spark is added BOOM.

On certain boilers faulty pcb will allow ignition when no fan running which also causes a hell of a bang.

ALL of which require checking by a suitably qualified gassafe bloke
possible gas valve sticking, injectors oversized, gas rate could be too high, or the pilot assembly out of position. ;)
So just to sum up, it can be caused by a whole multitued or mixture of problems.
If you have explosive ignition in your boiler all the time or even occasionally you should get it checked out by a gas safe person with the boilers qualification.
Without wishing to appear rude, if you say you understand about gas pressure etc, you should not need to ask the question, this is a very dodgy subject to start advising on it should be posted to the Combustion chamber :)
Can someone please explain exactly what causes Explosive Ignition, ie in a gas boiler

poolebybirth, are you asking this question because you are concerned with your own or someone elses appliance?

If so what is the make and model of the appliance.
perfectly normal thing to start thinking about really. You'd be amazed at the subjects which pop into your head completely randomly...

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