In an earlier contribution to this discussion,
Tony wrote:

Back to my problem......

I've uploaded a diagram of the boiler plumbing see what you think..


http://www.ultimatereef.net/photopos...t=500& page=1


When I was tracing the pipework I was drawn to a connection on the
22mm CH pipework, I've always thought that it was just a joint but on
furthur investigation it appears to be a valve, it took a torch and a
hand mirror to view the arrow and " TOP" markings at the very back of
the valve, Now maybe this is the problem of the reduced flow to the
upstairs rads. The very front of the valve as a small screw in it,
which is as tight as I can get it but there is still a very small drip
of water coming from it.. I feel a little stupid in not reconising the
valve, as I said thought it was just joining two pipes together and
that the screw was perhaps an earthing point..Does the screw have any
function

Is ther a way to test if the valve is faulty??

Ofcourse it could be a red herring,

.. Tony

The valve is what several of us have been asking about when we said (is
there an anti-gravity valve in the vertical pipe which feeds the upstairs
circuit?" - remember?

This is most likely the cause of your woes. From your diagram, it is obvious
that you have a gravity HW and pumped CH system. In such systems, the
upstairs radiators sometimes get hot due to gravity circulation when they
shouldn't (i.e. when the pump isn't on in response to a CH demand). The anti
gravity valve is a check valve, with a little weighted flap, which requires
a slight pressure to open it. The pump generates enough pressure to open
it - but convection doesn't.

For one reason or another, this valve isn't opening properly to allow flow
to the upstairs radiators. The most likely reason is that it is gummed up
inside - and needs replacing. There is an outside chance that someone has
turned the pump round to pump in the opposite direction - thus swapping flow
and return pipes - but that is unlikely. Make sure it's in the flow pipe
rather than the return. [It looks like it is, from your diagram, provided
the pump direction is as shown]. So my money's on the valve being seized up.
It needs junking, anyway, if it's leaking.
--
Cheers,
Set Square
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