On Fri, 05 Dec 2008 21:13:17 +0000, John wrote:

In article , Ed Sirett
writes
On Fri, 05 Dec 2008 00:33:42 -0800, Jim Walsh wrote:

I have a Vaillant TURBOmax plus combi boiler and I am experiencing an
intermittant problem with the supply of hot water from it. The central
heating function works just fine, but upon trying to draw hot water,
the boiler frequently supplies only lukewarm water. When the fault
manifests, adjusting the hot water temperature control on the boiler
makes no difference. The only thing I have found that seems to get it
working properly again (although not always at the first attempt) is
turning the boiler off and on again at the main switch. Some
additional info that may or may not be relevant: i) the problem occurs
most frequently in cold weather, ii) the boiler is mounted in an
unheated part of the house and iii) the boiler is about 8 years old.

Any help/suggestions gratefully received.

Thanks in advance, Jim.

I'd suggest from experience that if you can get an acceptable flow of HW
at times then this problem is absolutely the diverter valve. The reset
cause the system to recalibrate the motion of the diverter valve thus
giving a temporary releif to the symptoms.

To fix this fault you will need a new diverter valve (c. £100).


We have one of these in the Scout Hut which appears to have a partially
stuck pressure relief valve - drips and the pressure drops, then it is
OK for several days, then drips...


Expansion vessel? See Sealed CH FAQ.


I once found the maintenance and installation manuals on line but can't
find them anymore - anyone point me at a site??


Is it time to seed the Gas Appliance Manuals? About 1300Mb of Manuals for
a lot of gas appliances?





--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html