Isolating water supplies.

[securespark]

I can't seem to find in the wikis any info on isolating water supplies:

I need to solate HW to my bath. Cold is off the mains, so I'll shut off the main cock downstairs, no worries.

There is no valve on the supply pipe unfortunately, but is there a way to isolate the hot water without having to drain it all away?

Also, the shower has a gravity cold feed. Is there a way to isolate this simply?

Thanks.

 

[Symptoms]

secure - if you've got a cold water cylinder in the loft try sticking a bung in the outlet pipe (this tank will supply cold water to your H/W side). By bunging it you may cancel pressure to the H/W side and stop flow. Yep, you'll get a wet arm by reaching to the bottom of the cold water tank. Bung = wine bottle cork, carrot, or obtain a bung kit from B&Q.

 

[securespark]

Thanks. There is a CW storage tank in the loft.

In case that fails, are there any other ways?

 

[Symptoms]

secure - yep, pipe freezer or tie-up ball-cock above C/W tank (to prevent refilling), drain H/W side via bath tap 'till flow stops. Oh, and whilst C/W tank is empty consider fitting a gate valve somewhere convenient so you can shut off C/W suppy from tank in future.

 

[Whitespirit66]

Oh, and whilst C/W tank is empty consider fitting a gate valve somewhere convenient

Gate valve.

No sir.

Work of the Devil!

A full flow lever arm valve if you please.

If you must revisit the past and fit a gate valve, at least make it a Pegler brand.

 

[securespark]

Cheers fellas.

To a confirmed non-plumber like me that's some good advice: thanks!

 

[securespark]

I have found a couple of valves in the airing cupboard. This one acts on a pipe which feeds into the bottom of the cylinder on the LHS, where there is also a drain cock.

This second one acts on a pipe that feeds into the bottom of the cylinder on the RHS.

Are these CH pipes?

 

[xr4x4]

If you have a boiler, you should have....

22mm top, hot water out. (well get hot when hot tap is opened)
22mm/28mm very bottom cold water in from storage tank.(will always be cold)
22mm near bottom and one slighty above for boiler flow and return. (will get hot when boiler/hot water is on.

 

[securespark]

Thanks. I've just literally looked up a diagram of an indirect cylinder and then gone and looked at mine.

1. I have a 22mm coming out the top.

2. I have a feed in at the bottom LHS (the one with the gate valve on it and a drain cock at the bottom).

3. I have two pipes 1 above the other on the RHS of the cylinder.


So:

1 is the HW out?

2 is the cold in from the tank?

3 are the flow/return?

And if 2 has a gate valve in it (that works.... ) then will that close off the tank fed cold supplies and, once the HW is drained off, the HW too?

Or have I got it all wrong?

 

[Whitespirit66]

Sounds right.

Close off 2 - cold from tank. Then run hot taps for a few mins until flow stops. You only lose some of your hw.

Then you can do what you need to do.

 

[securespark]

You mean I won't lose the whole cylinder full?

If not, why not?

 

[xr4x4]

Just make sure the gate valve works fully, sometimes they let by a little, which could become annoying when you've cut the pipe..!

 

[xr4x4]

You mean I won't lose the whole cylinder full?

If not, why not?

Ermm hard to explain fully.

The cold goes in at bottom and pushes the hot out the top, the hot water outlet at the top isn't immersed in the tank, it's just an opening.

So if theres no cold water entering the bottom, once the level in the tank goes down past the opening at the top...it stops flowing.

 

[Whitespirit66]

You mean I won't lose the whole cylinder full?

If not, why not?

No, maybe less than 1/4 of the cylinder.

The weight of the water in the cold storage tank concentrates it's downward force in the supply pipe down to the cylinder. This force enters the bottom of the cylinder via this cold supply pipe and pushes/displaces the hot water upwards, out of top of cylinder to taps.

It's a bit like holding a short length of hose full of water in a U shape. As long as both ends are level, the water stays in the hose. Lower one end and some water will flow out of it.

By turning off the cold supply gate valve, the force down from the cold storage tank is blocked.

Hope my explaination makes sense.

 

[securespark]

Thanks!

While I appear to be understanding some aspects of plumbing, quite obviously others are tying my brain in knots....!