"Dave Clark" wrote in message
om...
Hi

I am not too clued up on boilers, but thought I would post a message
to see if anyone had any ideas.......

We have a Vaillant Combi (not sure on model at the moment) It is
relatively old, the Vailant phone number is missing the 01 so I
presume it is older than 9 years (i think BT changed the numbers in
1995)

Last week I woke to find the hot water not working, the heating was
working fine. We called out a repair man who thought it was the
'diaphram' that hits the switch when enough water pressure flows over
it. (apologies for not having the technical term for it!)

However, when he arrived later that day the ho****er was working. He
decided to take it apart to check it and found it wasn't broken. He
also noticed that the size of it was only a 1 inch rather than a 2
inch 'diaphram'. He said this would be the reason that we nearly
always have to turn on the tap full before the boiler kicks in.

So 100quid later he had replaced nothing, but it appeared to work,
until ...... this morning when the same thing happened, but by the
time I left for work, it was all back to normal.

My questions a

Could this be caused by a combination of occasional low mains pressure
and this smaller 'diaphram' that causes the boiler to never kick in?

Is this a known issue with older Vaillants?

How can I rectify it?

Is the 'diaphram' answer from our bolier man fact or fiction?

Any help will be appreciated

Regards

Simon

Is it a VCW 242 and is this "diaphragm" in a black plastic enclosure at
the bottom centre of the combi, operating a red microswitch via a little
mechanism coming from the black plastic enclosure? I think that there
may be some metalwork directly below the black plastic actuator, a valve,
from which a shaft going to a temperature dial emerges ( calibrated 0-9 I
recall )? I shan't go on in case it ain't the model I'm thinking of, le me
know,

Andy.