On 11 Feb, 15:32, John Rumm wrote:
Chade wrote:
John Rumm wrote:
Chade wrote:
On 9 Feb, 22:15, John Rumm wrote:

A rapid
rise to higher than normal (i.e. 3 bar) would indicate your expansion
chamber has lost its air charge. If you can find the charge valve for it
(it will look like a car type inflation valve (for that is indeed what
it is)), a quick press on the centre pin should yield a puff of air. No
air would indicate a discharged vessel in need of pumping up. Water
would indicate a ruptured diaphragm inside it, meaning it needs
replacing or, more likely, another one adding to the system elsewhere.
(allowing some air into a rad may function as expansion space for a
stopgap to get the heat back on)
Should I still do this test even though it seems to be working
normally?
Not it its working ok.

The pressure dropped again by about a third of a bar overnight. After
consulting a diagram in the manual I removed the inner boiler cover
and found that the valve is gently weeping. What spare parts do I need?

Which valve are we talking about...

There are two likely candidates: The expansion chamber valve and the
overpressure release valve. Since the overpressure release valve ought
to be piped outside in 15mm copper pipe, I expect that we are talking
about the former.


Sorry if I'm not being clear but I'm a bit confused. I just found the
expansion vessel in my boiler diagram and it has a 'car valve' on top
I depressed it and was greeted by a puff of air. There is a second
'car valve' in my boiler which is on top of what my diagram calls the
"Automatic air vent" that is the one that's weeping. Your first link
called it an "Bottle air vent".

http://www.bes.co.uk/products/109.asp

I could keep pressing the valve on top of the expansion vessel to see
if water comes out eventually but I'm nervious about letting out too
much air.