Old Boiler made a bang noise when start up

[Inverness]

old stelrad lpg boiler. My mates mum phoned me the another night and said the boiler made a bang noise now they can't get heating or hot water. It is a manual ignition type. Small pilot light to heat up thermo couplin to expand and allow more gas through to stay open.
What could this be? Thermo couplin replaced? I'll be going round tomorrow to further investigate but if I have you expertise I'll go with confidence!

 

[Last Plumber]

old stelrad lpg boiler. My mates mum phoned me the another night and said the boiler made a bang noise now they can't get heating or hot water. It is a manual ignition type. Small pilot light to heat up thermo couplin to expand and allow more gas through to stay open.
What could this be? Thermo couplin replaced? I'll be going round tomorrow to further investigate but if I have you expertise I'll go with confidence!

You need to know what the 'Bang' was. Was it explosive ignition?
If it was, check the pilot is in the right place and the right size. Check the burner pressure. Have a look at the Burner itself.

If it was a 'Bang' from Boiling water, it may have gone off on the Over heat stat. You'll need to find out why!

I'm guessing because we don't know the source or cause of said 'Bang'.

Just thought I'd offer a couple of thoughts of the top of my head.

 

[Inverness]

Thanks, all I was told is she tried to fire up the boiler then it went bang noise.
Now no heating. jobs like this that I don't have enough experience to diagnose the problem which is so frustrating at times

 

[Inverness]

It is a sealed system and the pressure had went too zero. I told them to fill it up and bleed all rads. They turned boiler on but it keeps tripping fuse?.

 

[Inverness]

Tripping fuse bang sound.

 

[AWheating]

its tripping the fuse/ breaker?