"Ed Sirett" wrote in message
news
On Wed, 13 Oct 2004 22:09:13 +0100, andrewpreece wrote:


"Wainscotting" wrote in message
...

"Ed Sirett" wrote in message
news On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm
is
new
so what else could be the cause? The boiler is about 15-20 years
old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and
locate
it
(and the microswitch mentioned in Andy's post).


If it's not a 242 then disregard what I said - I had a 242 and it had
the
same
symptoms as your combi, but I have no idea what your combi looks like
inside, unless Vaillant use a largely common design. Ed Sirrett is a
professional and has more of an idea than I do!


Vaillants of this era are somewhat unique in their design features.
I am very familiar with 242s this is a slightly earlier model called a
Sine.
It could be the diverter valve and the HW performance is still there
at a reduced level
because some water goes through the secondary heat exchanger.
I rather assumed this might be the case.

This model has a cold/hot standby switch (this can make the difference of
around 30 seconds for hot HW to arrive at the tap). It might be that the
switch or some of the control gear has turned off this facility.

As you rightly say the DHW flow sensor whilst newly diaphragmed is sticky
in some other way (this can certainly happen on 242s - but I don't know
whether it's the same kit on Sines).


--
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


Even in the summer I have to keep the radiator switch in the on position and
shut off all the radiator thermostats, plus, keep the cold/hot standby
switchin the "instant" position if I am to guarantee hot water. This time of
the year, with the heating on, if hot water is coming out of the tap and I
turn the cold/hot standby switch into the other position (not instant) the
boiler will shut off.
To recap....in the summer with the rad switch off I can't get any hot water
(most of the time). With the rad switch on I only get hot water if the
standby switch is in the "instant" position. With the heating on, hot water
takes up to 5 mins to come out of the tap and only then, with the standby
switch in the "instant" position. I will never get hot water if the standby
switch is not in the "instant" position. Perhaps it's time for a new boiler?