On Tue, 01 Jan 2008 13:54:36 -0800, jpcoetzee wrote:

These problems may not be related...

I have a Worcester Bosch Greenstar boiler (an early condensing combi)
about 6 years old. For some months the hot water has taking about 3-4
minutes to come out hot, as if the pre-heated store isn't working.
Timeswitch is set correctly, the boiler is not in ECO mode.

Also, in the last week the rads have been taking a long time to get
warm. The rads upstairs get hot first while the downstairs ones are
still cold. The burner comes on for about 3 minutes or so then off for 3
minutes, so the whole house is taking hours to heat up. There is a
clunking noise coming from somewhere inside the boiler.

Any ideas? Pump? Sludge in the pipes - the central heating system is
also 6 years old. Whihc should I check first?

Many thanks!

I would say you probably have some flow but not enough. I'd suspect a
partially detached impeller in the pump. Sludge is possibly involved but
as the symptoms came on suddenly I suspect the pump.

It is often possible to change the pump head as they are often big
standard grundfoss units, held by 4 allen bolts and a big o-ring.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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