Worcester Bosch 280 -not restart without pressing red button

[Safeas]

First post and long, so please go easy on me.

Have Worcester Bosch 280
installed from new, it has been great.
More recently, a problem happens.

I've noticed it happens mainly when using Kitchen hot water tap - boiler is in Attic-2 storey house. Tap will be used. turned off. used again say on half or less of full flow out of the tap - and...only then only cold water comes out. You can hear the boiler (fan?) whirring but it is no longer heating. Now, this doesn't always cause problem - but seems to be the best, obvious cause.

the boiler pressure remains ok, but the flame will not ignite automatically now. It means climbing up into the attic and removing the cover (now left off) to press the red reset button after either turning a hot tap on / or hot water (so as to give the boiler the stimulus to fire up again).

Boiler fires up fine and may go a week or more- seems to be no pattern

2 gas heating guys have been and looked at it:
the first was claiming at least the expansion tank needed replacing, then 'maybe' that would work.

I have found a slightly leaking radiator(due to be done soon) which has had the valves closed now and I check the water pressure dial doesn't drop too low - if it does drop I have worked out it is due to the Radiator - but this problem doesn't seem to be linked to the pressure.

Anyway. does this sound familiar to anyone?

 

[gblades]

I had a similar problem with one of these boilers. It turned out that there is a narrow copper pipe which connects the heat exchanger to the circuit board. On mine it was coiled up a bit which resulted in the flame heating the pipe itself up bit. This caused the boiler to think that it was overheating so it tripped out.

 

[Safeas]

I'll look into it, but doesn't sound like the same exact cause -
unless something has been disturbed or altered whilst the plumber/gas techy was looking into the other issue (which I now know as radiator) without discovering the cause of the occasional pressure drop.

The boiler will run for hours and heat the house - so not sure about it thinking it is overheating then.

The boiler could have been dormant all night, and then in the morning, use the hot tap - on and off, and it can happen.

Do you think that the narrow copper pipe on your boiler could have allowed your boiler to run for hours in the coiled up state you found it in?

 

[gblades]

Yes the fault I had only occured once every few weeks and never while the central heating was active (i.e with the boiler switching on and off).

 

[nickso]

id be checking a for a blockage in the brass tee above the pump or possibly in the primary heat exchanger itself, both well known issues on these.

i'd also check the overrun was working, ant remember if its pump or fan on these but it will want to clear the heat in the heatex after a demand, if it doesnt you may get nuisance lockouts every so often.

 

[Safeas]

Thanks for any replies

Will look into them soon / get some other Gas engineer in and make sure these are ruled out.

Hopefully will get to the bottom of this - I have trawled through several other sites also, and boilers being not something I have ever analysed or studied, I will carefully learn what my limits are and not tinker around.

I vow to keep this updated - out of interest to others. Hopefully with the problem soved