On Tue, 21 Oct 2003 22:09:02 +0100, Dougie Nisbet
wrote:



Could you clarify exactly what you mean by 'fill point' and 'drain point'
- because I suspect I have neither. Oh, hang on - I'm wrong. Re-reading
the rather good http://www.makewrite.demon.co.uk/SealedCH.html I certainly
have a Fill point, but I can't see any sign of a drain point. Neither
could a plumber who replaced a radiator for me a couple of months ago. He
drained (more or less) the system by shoving a bit of hosepipe into the
rad in the kitchen. The fill hose is connected and has been much used
until the plumber replaced the faulty rad which was leaking and
de-pressurising the system.

Look for something like

http://www.screwfix.com/app/sfd/cat/...12232&ts=73105

fitted at a low point normally near the boiler.

There should really be one at every low point.

Otherwise, after you have drained via a low radiator, you could fit
one using a push fit tee.

http://www.screwfix.com/app/sfd/cat/...73302&id=17972




switch off, release pressure at the release point.

connect fill and drain hoses, open drain valve, close pressure
release valve.

Turn on supply. Then by opening and shutting valves round the house,
you can send a fast stream of water through each rad in turn. This
should remove a lot of the sludge except if a rad is solidly blocked;
if so, then you will have to remove that rad and flush it.

I understand the fundamentals behind what you're saying but I'm struggling
with some terminology. 'pressure release valve' - is that the bypass valve
that connected CH flow and return just below the boiler?

No. Take a look at www.bes.ltd.uk and the section Plumbing-Central
Heating-Central Heating Sealed System Equipment.

You should find a valve somewhere (typically near the expansion
vessel) with a knurled knob. It could also be near the filling point.
It may well have a label with 3 bar on it and there should be an exit
pipe to a drain. However, since there are other questionnable
aspects of the system then it may not have that. There *must* be
one on the system somewhere though.
It is possible that it is inside the boiler, especially if the
expansion vessel is in there as well.

If you don't have a pressure relief valve, then it is probably time to
seek professional help because the system would be dangerous without
one. There is no reason why yoiu couldn't DIY the addition of such a
valve, but absence would be an indicator that there could be other
problems.

Assuming you can find the valve, it is not a good idea to use it to
drain or even depressurise the system. Pieces of crud or scale
could easily become caught in it and then the valve won't seal again
and a new one will be required.





Will I definitely have a drain point and I just haven't found it yet? Or
could it be that the installers were too busy eating digestives to bother?

Based on some of the oddities you've mentioned, this is entirely
possible. It's laziness at best and incompetence at worst.
If you have any doubts about the system, it's also possible that the
gas installation has not been done properly either.
I don't want to frighten you, but if you are not 100% certain, then a
prudent move would be to get a CORGI registered heating engineer to
look at it (not BG since they are generally expensive).




..andy

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