On Wed, 22 Oct 2003 11:21:14 +0100, Andy Hall wrote:

On Wed, 22 Oct 2003 09:02:05 +0100, Dougie Nisbet
wrote:

[quoted text muted]

In that case I take your point that there may be sludge build up in
the pipes.

Given these circumstances, I think I would probably put drain cocks in
the 15mm pipes going up to the radiators or in the 22mm below the
floor in several places. In the latter case you would force the
crud out under pressure anyway. In plastic, this is very easy to do
but you should use a proper pipe cutter and not a saw.



www.bes.ltd.uk

Drain Cock 10529

Tee 7080 (15mm)

Tee 7082 (22x22x15mm)

Cutter 7141



My thinking in having the exit point(s) close to the radiator is to be
able to get the crud out of the system close to where it is being
generated (largely the radiators.) Over longer lengths of pipe it
may settle out and then you have merely distributed it further.



.andy

To email, substitute .nospam with .gl


[ Later that week ,,, ]

Well, isn't plubming fun. Thanks for all your advice. I've had a
prelimenary reccy, and much fun was had by all. Dougie's top 10 tips of
the day include:

1. Check that radiator - it really is twice as heavy as it looks.
2. Always consider that the radiator may only be held to the wall with
chewing gum and a prayer, and it may never ever want to go back there.
3. If you go under the floor and try and understand your central heating
pipework, you'll find yourself in a maze of twisty winding conduits, all
alike.
4. You will forget that you left the air-bleed valve open to hasten
radiator drainage when you reconnect. No really, you will. You will you
will you will you will.
5. What's that strange hissing noise? (see 4.)
6. Radiators are really heavy.
7. See 6.
8. Can I phone a friend? (see 6 & 7)
9. No, it slackens that way.
10. Keep a toothbrush handy.

Having had zero experience with plumbing, I decided to start modestly. I
removed the bathroom towel rail with little difficulty and flushed it out
in the back garden. I notice it helps to give it a good shake while you're
flushing it through. The hose pipe wouldn't fit inside the rad but the old
bit of extortianetely priced plastic that once formed part of a lotus pond
fountain did the job very well.

Once the rail was back in the bathroom and everything switched back on,
things looked pretty promising. It got nice and hot, then it cooled down,
then it stayed cold. After much soggy experimenting with hosepipes I'm
pretty sure the problem is due to a gunged up Return from the rail to the
CH SuperHighway. There's a 15mm (at least I'm assuming it's 15mm -
it could be smaller) branch line from the rail to the 22mm backbone that
is located conveniently a Good Crawl away three rooms from the access
hatch.

The easiest way to flush the system is to introduce mains pressue via the
filling loop at the boiler. I've tried some localised flushing by
connecting hosepipe to the mains tap directly to the rail. But I'm coming
to the rather depressing conclusion that I have, to use the rather
unsavoury Izal toilet paper analogy, just move the yck around a bit.

I've ordered a bunch of
https://www.screwfix.com/app/sfd/cat...80920&id=11074 rad valves
wbich I think will make my life easier in the long run. My guess is that
giving the towel rail a good clean just provided a temporary reprieve
(although the other rads got piping hot as a bonus) and there still
exists a load of crud in the Return branch line from the rail to the 22mm
backbone. Cutting a drain cock into the 22mm backbone under the floor
isn't massively feasible as there's no obvious way - hmmm - unless I did a
Tee into the 22mm, (something like
https://www.screwfix.com/app/sfd/cat...81470&id=12900) then fed
some 22mm out of an air brick to The Outside World, and put a tape on
that (what would I use for that?) ) ...

As things stand I'm waiting for Mr Screwfix to deliver a load of rad
valves that will give me a few more options on flushing rhrough the
system. With a bit of imaginative use of the filling loop and by-pass
valve it should be possible to flush through different parts of the
system. Mains pressure isn't much to write home about though with lead
piping from the supply.

Another possibly limiting factor is that my TRVs are the old
fashioned single direction type. Even if they are fully open perhaps
this will limit my options of forcing water 'the wrong way' through
the rad to try clearing bloackages. since my I know you're a fan of Peglar
from your writings elsewhere, and I'm tempted to bite the bullet and order
a wad of
http://www.screwfix.com/app/sfd/cat/...05 2&ts=82142
although having TRVs is largely unecessary for me as I prefer to use a
Room stat for general control of the overall hose temperature.

So, close but no cigar. I still have a cold bathroom towel rail. But
there's crud in them there pipes - and I intend to flush it out!

Dougie