problem with glow worm 55f

[knightster]

hello everyone could some one please help with this problem ive got with my boiler.( glow worm 55f). the boiler starts nice, main burner comes on but shuts down after 30 - 40 secs. at first we thought it was the pump ,which after inspection did need replaceing,but still no help,then some one come round and said it was a fault on the p c b so that then was changed,still no change.to be honest all the main checks have been done water in f & e cylinder stat o.k room stat o.k boiler stat working gas valve been checked and o.k im running out of ideas and money any help would be great. thanks alot

[Fentoozler]

Not too familure with this boiler - does it have a permanent pilot? If not, do the electrodes continue to spark during the 30-40 seconds before the boiler goes off?

[Ed Sirett]

After the pump was exchanged the valves on both sides were opened weren't they? It could also be an air lock especially if the air is in the pump this would also prevent the circulation which would give this symptom.

A very simple check, put the boiler on a low setting when the boiler has cut out does can you get the boiler to start again for another few seconds by turning the thermostat up? If so the problem is almost certainly outside of the boiler the primary water just not being shifted.

[knightster]

thanks for the replie, it is not a permanant pilot and no it doesnt carry on sparking ,once the main burner is lit ,it stops,any more ideas please

[knightster]

thank you ed for the help . i know the valves are open but there does sound like there is some air in the system ill give that test a try. ed,if there is a air lock. what would you think is the best way of purging it....thanks again

[Ed Sirett]

The key test is to find out if the fan stops slightly before the flame stops or at the same time. If as geoff suspects the fan is the culprit then there will be a short delay before the flames goes out as it takes a small amount of time for the APS to detect the failed fan.

If the problem is not the fan then the overheat sensor is likely to cut the gas and the fan simultaneously.

If the problem is air then we can deal with that once the fan is out of the dock.

[knightster]

ed-in replie to that last message the fan goes out just before the main burner,which means the fans is at fault then i take it ?

[knightster]

ed- the fan does stop just before the main burner goes out, am i write in taking it that the fan is at fault ?

[Ed Sirett]

That's what I'm saying. So it's off to cetltd for a recon'd fan.