In article , fred writes
In article , Tim Mitchell Tim@sabretec
hnology.co.uk writes
Have fixed the pipes down, has reduced the volume of the banging but it
is still doing it.
There are some funny things about the way it's piped. I think I know
where the airlock is, there is a 15mm pipe which forms the return from
the HW cylinder and the manual bypass, this has a high spot in it
because of the way they have connected it. This 15mm pipe runs
separately, alongside the 22mm return pipe from the CH radiators, then
joins together in the floor above where the boiler is. I don't
understand why it's done like this, and not simply joined into the
return where it passes over the top of it. The banging only happens when
the system is heating HW and not radiators which seems to bear out my
theory of it being in the return from the HW cylinder coil.
I have drawn out the system he
http://www.tega.co.uk/timch.gif
Can anyone illuminate me as to why that 15mm pipe is like it is? And how
I can get the air out of the pipe, other than by cutting it and fitting
a bleed point (I am tempted to do this, but it means draining it down
again). I have tried turning everything else off to send max flow down
that pipe but it has made no difference.
I can see no need for the separate return. Is that a lockshield in the return
path of the HW circuit and how is it set? In order to stabilise mine, I have
to throttle the HW loop quite a lot, but not so much that HW perf is
compromised. Could you try opening the lockshield just a tad (from
closed) & see if your banging is damped - I don't think the keston pump
control system likes to see an unrestricted loop.
The circles with Xs are gate valves. I haven't tried messing with that
one, I will work out its current state and try some different settings.
It is perfectly happy if the central heating valve is open. It bangs
worst if both CH and HW are open, then the CH valve closes, which makes
the boiler reduce its output to 1 or 2 lights, then it bangs for about
15 seconds, then it settles down and all is peaceful again.
--
Tim Mitchell