I have a 15mm pipe supplying my upstairs mains water for the bathroom and
loft storage tank.
Downstairs there is a stop cock in this pipe and ideally I would like to
have a drain valve immediately above the stop cock to allow me to drain all
the cold water pipework upstairs.
Would appreciate any advice on parts I could use for this.
Tia

mackem wrote:
I have a 15mm pipe supplying my upstairs mains water for the bathroom and
loft storage tank.
Downstairs there is a stop cock in this pipe and ideally I would like to
have a drain valve immediately above the stop cock to allow me to drain all
the cold water pipework upstairs.

Pipework, or all water?
If all water, you're going to need either a seperate pipe, or a anti
backflow valve just before the existing shutoff valve (in case of low
mains pressure), an anti-backflow valve mounted the other way in the tank,
so it'll let water flow out, connected to the existing pipe, a tee and
a drain-valve just above the existing stopcock.
Otherwise, a T above the existing valve, followed by a valve will work,
sort-of.
(as there is no means of admitting air, so the pipe may take a while to
drain.)

Would appreciate any advice on parts I could use for this.

"Ian Stirling" wrote in message
...
mackem wrote:
I have a 15mm pipe supplying my upstairs mains water for the bathroom and
loft storage tank.
Downstairs there is a stop cock in this pipe and ideally I would like to
have a drain valve immediately above the stop cock to allow me to drain
all
the cold water pipework upstairs.

Pipework, or all water?
If all water, you're going to need either a seperate pipe, or a anti
backflow valve just before the existing shutoff valve (in case of low
mains pressure), an anti-backflow valve mounted the other way in the tank,
so it'll let water flow out, connected to the existing pipe, a tee and
a drain-valve just above the existing stopcock.
Otherwise, a T above the existing valve, followed by a valve will work,
sort-of.
(as there is no means of admitting air, so the pipe may take a while to
drain.)

It's just the pipes I want to drain, so like you say I think I'll put a T
piece just above the stopcock. From looking in the Screwfix catalogue it's
not clear how I would attach a drain cock to the T piece.
How would I do this?
Tia

In an earlier contribution to this discussion,
mackem wrote:

I have a 15mm pipe supplying my upstairs mains water for the bathroom
and loft storage tank.
Downstairs there is a stop cock in this pipe and ideally I would like
to have a drain valve immediately above the stop cock to allow me to
drain all the cold water pipework upstairs.
Would appreciate any advice on parts I could use for this.
Tia

You could replace the stopcock with one which incorporates a drain point -
or you could simply insert a 15mm tee into the pipe immediately above the
stopcock, and fit a drain point into the branch. Take you pick between
solder, compression or push-fit fittings - you can get the appropriate bits
for any of these types.

This will enable the *pipes* to be drained but not, of course, the cold
storage tank.

While you're at it, you might consider fitting a full-flow quarter-turn
valve innediately above the stopcock and below the drain point. When you
want to turn the water off, use this quarter turn valve rather than the
stopcock - it's much easier and quicker.
--
Cheers,
Set Square
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In an earlier contribution to this discussion,
Ian Stirling wrote:

Otherwise, a T above the existing valve, followed by a valve will
work, sort-of.
(as there is no means of admitting air, so the pipe may take a while
to drain.)

If you run off some hot water - after turning off the cold - the tank level
will drop a bit, allowing the ball valve to drop. This will admit air. [I
suppose you could just force the ball down with a piece of wood to avoid
having to drain any hot off]
--
Cheers,
Set Square
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In an earlier contribution to this discussion,
mackem wrote:


It's just the pipes I want to drain, so like you say I think I'll put
a T piece just above the stopcock. From looking in the Screwfix
catalogue it's not clear how I would attach a drain cock to the T
piece.
How would I do this?
Tia

It depends on which technology you choose!

Screwfix 13349 or 17843 are designed to be used with solder fittings. They
have a 15mm inlet pipe which has to be soldered into the branch of the tee.

Screwfix 65868 screws in. You would use this if you are using compression
fittings. You would need a 15mm comp x 15mm comp x 1/2" BSP female iron
tee - which has a threaded boss on the branch for the drain fitting to screw
into. [Can't see one in the Screwfix catalogue - but your local plumbers
merchant will have one.] Seal the threads with PTFE tape.

Screwfix 12232 is very similar to 13349 etc. - but seems to be the one to
use if you're going the push-fit route. It just pushes into the branch of
the tee - where it is automatically gripped by a gripper ring and sealed by
an 'O' ring.

If using either solder or push-fit - particularly solder - you'll have to
make a good job of cleaning the pipe either side of where you cut it.

--
Cheers,
Set Square
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"Set Square" wrote in message
...
In an earlier contribution to this discussion,
mackem wrote:


It's just the pipes I want to drain, so like you say I think I'll put
a T piece just above the stopcock. From looking in the Screwfix
catalogue it's not clear how I would attach a drain cock to the T
piece.
How would I do this?
Tia

It depends on which technology you choose!

Screwfix 13349 or 17843 are designed to be used with solder fittings. They
have a 15mm inlet pipe which has to be soldered into the branch of the
tee.

Screwfix 65868 screws in. You would use this if you are using compression
fittings. You would need a 15mm comp x 15mm comp x 1/2" BSP female iron
tee - which has a threaded boss on the branch for the drain fitting to
screw
into. [Can't see one in the Screwfix catalogue - but your local plumbers
merchant will have one.] Seal the threads with PTFE tape.

With my level of expertise it'll have to be brass compression fittings !!
I'd seen the Screwfix 65868 drain cock which is referred to as 1/2 inch bsp
but what threw me was that the picture in the catalogue shows a plain shank
where I was expecting to see some threads.
However, problem now solved. I was looking for a 15mm x 15mm x 1/2 bsp T
piece on the BES site and found a 15mm T piece with a built in drain cock
http://www.bes.ltd.uk/nav_graf/frames_cat.htm
Thank you very much for pointing me in the right direction - much
appreciated.