Condensing boiler (Keston) - intermittent fault

Postby booboo » Sun May 13, 2007 2:55 pm

My Keston condensing boiler is approx 10 years old (fitted in house from new). It has been working fine until last year when it stopped working. Symptoms were boiler failing to fire but the water pump stayed on continually making a 'buzzing' noise. This noise does not occur when the boiler fires correctly and in normal operation the boiler fires, ignites, heats water and then stops (as does the water pump). In Jan the pressure switch failed causing water to leak from the boiler - this was fixed and the boiler worked fine for 2 months or so and then the intermittant failure began again.

The intermittant nature of this fault means that the boiler will cease to fire every few days or so. Swithing off at the mains for a long period (a day or so) and then switching back on at the mains can sometimes coax it into firing - but sometimes not; these times the 'buzzing' noise of the pump running can be heard.

Is this an easy fix - we have spent £500 on spare parts so far - new boiler would be only £700 for Keston replacement?

Could this be a pressure issue which is seperate to the boiler - and if so how would that cause the boiler to fail to fire?

Can anyone please help me before I get British Gas out - they have quoted £5K to fix replacing boiler, tank, whole schebang?!! I nearly had a heart attack!! Bang goes the new kitchen tile fund....!
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Joined: Sun May 13, 2007 2:38 pm


Simply Build It

Postby Paul Pepper » Tue May 15, 2007 6:55 pm

most Keston boilers have a pressure switch that senses the system pressure and will prevent the boiler from firing. The pump, however will run on. If the switch has muck on it, it can intermittently fire up when it feels like it. Kestons are funny beasts and like developing dodgy faults that seem to rectify themselves. I would honestly think about changing it if you can. (British Gas will always be the most expensive - try taking their quote to another CORGI man and seeing what they can do!)
If you give me the boiler's model or GC & serial number, I'll try & find a sequence of operation/fault chart for you.

Paul Pepper
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Joined: Fri May 11, 2007 6:02 pm

Postby booboo » Wed May 30, 2007 8:15 pm

Paul - thanks.

The boiler has worked intermittently for the last week - until i cleaned up the 'Flue overheat thermostat' and replaced it (noticed this when i touched it with tip of screwdriver and boiler fired up!). Now working fine! New thermostat is approx £17, so will replace if it happens again. For info - its a keston 80 condensing boiler. A friend of a friend (plumber) has quoted appprox £2K for new (he recommend a WorcsterBosch) boiler.

Thanks for your help!
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Joined: Sun May 13, 2007 2:38 pm

Postby booboo » Wed May 30, 2007 8:20 pm

GC number is 41 451 03. Thanks!
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Joined: Sun May 13, 2007 2:38 pm

Postby wishiwascorgi » Fri Jun 15, 2007 12:39 am

if your friend says £2000 for a worcestor bosch boiler he is no friend.
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Joined: Thu Mar 29, 2007 12:00 am

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