glowworm kfb 50

[taxexile]

just looking for some advice on my glowworm kfb 50.supplys heating only.10 year old approx.
has been off during summer as we have seperate water heater.
has been erattic operation all last week,it will only work with the inner case removed.i have asked my usual gas engineer to look at it but he cannot get here till the weekend.
sympton is pilot lights but still sparking.no main flame.
he asked me to check the following,is flue clear.yes.
check venturi is clear yes it is.blow through both air tubes,they are clear.
it had a pcb, gas valve and pilot burner/pipe during routine service in august.
any ideas lads.thanks.

 

[meldrew's_mate]

Ah, the kitchen friendly (but not gas fitter friendly) boiler...

If it's still sparking after the pilot is lit then the pcb is not "seeing" the pilot flame. This indicates the need for a new PCB, despite the fact that you've just had one.

I'm intrigued to know what the reasoning was behind replacing at least two components (GV and PCB) which clearly were working up to the point of the service. No comment on changing the pilot assy., they can be prone to blocking.

Would like to know what your gas fitter says...perhaps he could put the old PCB back in to check it

MM

 

[taxexile]

thanks for reply.
pilot burner kit was also changed inc injector/electrode.
pcb was changed due to not sparking.
gas valve was changed as it was leaking gas internaly (letting by i think he said )
but this boiler starts up first time when inner case cover removed,maybe pulling more air into boiler to provide ignition.? air gas mixture/fan speed.
with cover reattached with the 2 screws it will only light the pilot and continue to spark.
umm.

 

[Andy165]

Thats one helluva service visit... new pcb, gas valve and pilot assy! As boiler is over 10 years old it would have been better to recommend an upgrade to a new condensing boiler. If boiler works with inner case off, most likely cause is not clearing P.O.C. fully, how well was it serviced originally? Did it work before it was serviced?

 

[meldrew's_mate]

...with cover reattached with the 2 screws it will only light the pilot and continue to spark...

Because either the pilot flame isn't impinging on the sensing electrode, or the PCB has a fault. Having the cover off will possibly distort the pilot flame so that it burns where the electrode is.....
...in which case it can't be the PCB...

MM

 

[taxexile]

thanks meldrew and andy.
although the boiler is 10+ years old it is only used for heating in the winter months.
the only parts in 10+ years are as above,if you can reccomend a new boiler which will be as reliable as this one let me know.
my gas repair man is on holiday due to family illness,at the monent,he thinks its the fan has slowed down although he says an interlock switch should prevent it fireing up at all.
just found some literature which came with boiler it was fitted 12 years ago by previous house owner.
thanks again.

 

[namsag]

Hope you are not leaving the inner case off to keep it working and only doing that to test it .

it is still sparking when case is on even though pilot is on /but if you take case off and pilot lights and stops sparking then fires up .

Things to look at.
Clean/adjust pilot as fan is taking too small a pilot away from electrode stopping proper current getting sent back to board or electrode lead is possibly shorting onto case somewhere

 

[Meldrew's mate]

...he thinks its the fan has slowed down although he says an interlock switch should prevent it fireing up at all.quote]

He's wrong about the fan, if it didn't operate the APS ("interlock switch") it wouldn't get as far as lighting the pilot, or even sparking.

Advice has been given which should cover it, have the pilot size and direction checked by a competent person i.e. CORGI gas fitter.

 

[Meldrew's mate]

...he thinks its the fan has slowed down although he says an interlock switch should prevent it fireing up at all.

He's wrong about the fan, if it didn't operate the APS ("interlock switch") it wouldn't get as far as lighting the pilot, or even sparking.

Advice has been given which should cover it, have the pilot size and direction checked by a competent person i.e. CORGI gas fitter.

 

[SvenVanLagerTop]

No. 1 Make sure pilot injector is not restricted.

No. 2 Make sure you have a gasket around the pilot assembley. If not, or if it is damaged, you can get a draught being drawn in and across the pilot burner making it very difficult or impossible for the pilot to establish.

 

[taxexile]

thanks all,it was the fan running not running at full speed all the time.
regards.