combi boiler problem

[36TEAK36]

Hi, just asking a question for a colleague who has a combi boiler problem.

This morning my colleague discovered she had no hot water, but all of the radiators are working fine and are warm.

I know absolutely nothing about heating systems, but I would have thought that if the combi boiler was faulty and there was no hot water, the the radiators would also be cold, or do radiators have their own built in heater element?

Any help would be most appreciated.

[chrisrob]

We have this problem with our boiler at times. When trying to get hot water, close to the boiler we can hear a continual clicking and though the pilot's alight, the jets fail to ignite.
We had an engineer out and he said it was a relay on the circuit board. Although relays cost only a few pence, he said he'd have to change the whole board at around �150 plus labour. As the boiler's old and we'll get a new one when we can afford it, we decided to try and live with this occasional inconvenience. If I was corgi registered, of course, I'd be allowed to remove the circuit board myself and I'm sufficiently competent with a soldering iron to replace a relay.
dth?

[gucciman]

its almost certainly down to a faulty diverter valve but could also possibly be a faulty flow switch or thermister.