On Sat, 21 Feb 2004 05:06:15 +0000, Richard Hamer wrote:

Having isolated put a stop end in the hot water pipe out of the
boiler, so that only a single (washing machine) outlet is in the run,
the hot water problem remains.

The tap needs to be turned fully on to get the boiler to fire up. This
is a much greater flow than used to be necessary for hot water, and
the kitchen sink and shower are unable to trigger it.

I am therefore sure the problem is within the boiler itself. All other
problems have been fixed. Bosch will be back in a week to take another
look, but in the meantime does anyone have any ideas on where the
problem might lie, eg the hot water diverter valve / flow switch
sensor thingy?

The web site is down ATM so I can't check the precise means by which the
boiler senses water flow. However the symptom of insensitivity to HW flow
is very likely to indicate a split diaphragm of some sort.
This part will likely not exceed £40 (whole valve) or £10 a replacement
diaphragm.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html