Joe wrote:
John Stumbles wrote:
On Mon, 19 Feb 2007 15:20:59 +0000, Joe wrote:

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if
you're
in a hard water area).
No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

... I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting
period.

If you watch the gas meter (clock dial) while someone else turns on a hot
tap can you see if the boiler is starting up at a low rate and then
getting to full rate much later?


That could be difficult. We have an old style meter literally on the
floor under the stairs. I may get curious enough to try, but I assume
I'll have to get the proverbial Man In to fix the boiler anyway. I was
hoping to get some idea of the problem, as this seems a reasonably
popular model, but it doesn't look as if anyone has seen this before.

More information: I confirmed that no pipes get hot during the dead
period, and being an electronics engineer, I gave the cabinet a few
thumps was rewarded with a blinking 'computer crashed' light.

Turned off the tap, reset it and tried again. Again the pipes stayed
cold, and the flue showed only a very slight heat haze. Then after
about twenty seconds, the sound started to fluctuate slightly and
then the pipe got hot.

So this looks like a flame-failure device fault. Does anyone know
whether this is purely thermo-mechanical, or whether it's an electric
valve and sensor? The latter would seem to imply that the computer
crash was the result of a dodgy joint, and it might be worth reseating
everything. I would assume if it's purely mechanical then it needs
replacing.