HELP! Drain airing cupboard hot water tank

[Smileysmile]

Ok guys I have to solder a solder ring onto a downstairs toilet hot water pipe. I currently have a push fit plastic connector inplace but I was told by my plumber a solder joint would be better. The pipe join will be concealed behind plasterboard.

I have attached a photo of my water tank that I was told needed to be drained. First the cold main feed to house was to be isolated. Then the hot water tank. But as you can see their are a number of red gate valves that surely a couple isolated would all that would be needed?

Possibly keeping the hot water but isolating it from the pipes I need to work on. I tried it before and had a drip drip all the time and even tried bread so I could work on the solder. In the end I put a push fit connector on. Maybe I need to give it more time to stop dripping? Ok looking at the attached photo which gate valves do I need to isolate?
Any help will be gratefully appreciated

 

[45yearsagasman]

To isolate your hot water it's the gate valve on the LHS of your picture. They can sometimes be unreliable so maybe you could insert a bung in the CWS tank outlet.
Open all your hot taps.

 

[Smileysmile]

Hi. The CWS is? Is that the central water system in loft? I have 2 tanks in the loft. One is a small one central heating the large is the hot water supply? They both have isolation valves? So Isolate which one? Oh and thanks for replying

 

[mogget]

Cws = cold water supply or cold water storage cistern. Ie, the big tank in the loft.

The gate valve on the left should isolate the hot water supply. However if it doesn't close properly you will need to bung the outlet from the cwst as stated above. Also do not heat the cylinder whilst you're doing the job or the water will expand to where you don't want it.

 

[Smileysmile]

BUNG? As in isolate the water going into the main tank in the loft? ONLY if the gate valve doesn't fully close which would be evident if I have a continous drip from the pipe I am working on?

 

[Smileysmile]

BUNG? As in isolate the water going into the main tank in the loft? ONLY if the gate valve doesn't fully close which would be evident if I have a continous drip from the pipe I am working on?

 

[Madrab]

Bung, as in stick a bung into the outlet pipe at the bottom of the CWSC tank in the loft that feeds that gate valve, stopping the water running down to the ctlinder ....then run the hot taps till no more flow. Oh and remove said gate valve and replace it while you're at it.

 

[Smileysmile]

I see. Bung the hole at bottom of tank rather than drain it? So no water will flow into pipe that feeds the hot water tank.
Replace the gate valve? Any reason for this? Because if their is drip after closing it then it's obvious the valve is not closing properly so replace it? Hmmm Maybe I could do this myself *rolls eyes*

 

[Razor900]

Just turn the incoming water main off and open the hot taps until the cistern is empty and they stop dripping. Bear in mind that unless there's a drain off at a lower level then you're working at there will still be some water in the pipe. You don't need to drain the cylinder

 

[Madrab]

That's the stuff Smiley. You've sussed it.

Firing on and replacing it yourself ... hmm... honestly... if you're not sure then don't try is my advice. All sorts of fun if you haven't bunged the tank feed properly and you take the old gate valve off.

 

[Smileysmile]

Just turn the incoming water main off and open the hot taps until the cistern is empty and they stop dripping. Bear in mind that unless there's a drain off at a lower level then you're working at there will still be some water in the pipe. You don't need to drain the cylinder

Don't need to drain the cylinder? Now I am confused. I thought by turning the water mains off from the stopcock into the house then opening the taps eventually you will drain both the cylinder and the tank in the loft?

So if I turn the gatevalve off on the left side of the cylinder that would stop the water from the loft tank feeding the cylinder? With the taps open the water will gradually empty from the cylinder? Isn't the cylinder where the water is stored to feed the pipes I am working on?

So would I BUNG the loft tank outlet hole with a rag perhaps?

 

[gavgas]

hot water comes out of the top of the cylinder and can only do so if cold can go in at the bottom. So you either isolate cold feed into cylinder with gate valve on left or isolate mains cold feed to main storage tank in loft then run hot taps till they stop. the storage tank in the loft will be empty and the cylinder still full.

 

[Madrab]

If you turn off that gate valve, but the open hot water tap doesn't stop dripping, as you said in your original post (sometimes gate valves don't close completely when they're older). Buy a bung and place it into the cold outlet in the bottom of the cold water tank in the loft, the dripping should then stop (no water now feeding the hot water cylinder from the cold tank, therefore no pressure to push the water out of the top of the HW cylinder into the hot pipework)
That will then allow you to solder the fitting.

 

[Smileysmile]

This is annoying. Paid £18 for a rubber black bung to plug the outlet hole in bottom of water tank. The instructions say use a screwing action. But I don't want to use to much force as I might break the pipe or something. Surely their is an easier way as the pipe I am working on is still dripping and nearly filled the bucket I need to do this today. Anybody reading this or are you all slogging it out in work?

 

[avonmouth]

Empty the tank using a hosepipe = syphon after first closing mains supply to the tank.