Combi boiler - turning but not burning

[Cock Womble]

Right then, yet another combi boiler thread (they're great, aren't they?) and yet another problem with my particular example.

Symptoms:

When the timer kicks in, the burners will ignite and heat the water.

For a short while.

Then the burners will go off, but the pump will continue to circulate luke-warm water to the rads and taps. Hence, a cold flat and a tepid bath.

Then the burners will kick off again for a short while until they can't take any more and give up.


So, what bit has gone wrong, where can I get a new one and can I fit it without killing myself?

[cjs]

What make, model, age? Could be the divertor valve sticking however that usually sticks in the heat circuit or the DHW circuit so you get one but not the other. They can be straight forward to change, I have done mine on my Potterton, cost me around £90 for the valve so it is not something you should do unless your sure.

[Ferg]

Sounds like a thermistor not reading the temperature correctly, but a proper diagnostic check would be better.

[Cock Womble]

cjs said:

What make, model, age? Could be the divertor valve sticking however that usually sticks in the heat circuit or the DHW circuit so you get one but not the other.

It's an Icon 23t, of indeterminate vintage. The diverter valve went last year and was replaced, so I doubt if it's that.

Sounds like it could be the other thing - is that a DIY job?