Worcester Bosch 240 combi boiler fires and cuts out

[DonDiy]

I have a Worcester Bosch 240 combi boiler. It is firing but immediately cuts out.
I'm in a soft water area and the Diverter valve was replaced just over a year ago.
Here's the symptoms:
Regardless of rad valve positions or hot water demand boiler won't run,
Honeywell reset button trips,
Pressure gauge at 0.5 bar when cold,
All rads bled and OK,
No leaks identified.
When honeywell is reset, burner fires up to the sound of loud gurgling in the boiler, pressure shoots up to 2.0 or 2.5 bar then burner cuts out, honeywell trip.
Doesn't fire up for hot water either.

Any suggestions would be gratefully received.

 

[petit_pablo]

Circulation problem, likely to be the pump.

 

[gassafeengineer]

check pre charge presure in expansion vesell aswell this will explain the pressure problem


and what petit pablo says

 

[davebgas]

Could be a blockage on the primary side as well

 

[Agile]

It sounds as if you have two faults!

The first is easy to diagnose and correct. See the FAQ about expansion vesels, either failed or needs repressurising.

The rest of your post is not consistent! For the pressure to increase the boiler would have to be firing for at least a few minutes, buts thats not what you have said.

Could you be a little more informative and then I can identify your problems.

Tony

 

[holty]

try topping the boiler above 0.5. to 1

 

[davebgas]

try topping the boiler above 0.5. to 1

Hows that going to help when the pressure is jumping up to 2-2.5???
Obviously a problem causing the pressure rise and burner cut out.
This doesnt sound like normal heating expansion.

HW microswitch could be stuck

 

[holty]

missed that bit

 

[holty]

by the way davebgas. have you moved country or is it time i really need to sleep it off

 

[davebgas]

Fancied a change of virtual scenery, stay elusive and all that

 

[bengasman]

try topping the boiler above 0.5. to 1

Hows that going to help when the pressure is jumping up to 2-2.5???

Steam developing due to lack of flow?

 

[DonDiy]

Thanks folks,
Have isolated gas supply and reset honeywell.
Not a lot going on, pump doesn't appear to be running but pump heats up, too hot to touch.
Looks like pump needs replaced???

 

[kevplumb]

easy job then

you can just change the head BTW