Isolating hot water supply.

[amfisted]

Hi All

Hopefully a query with a fairly easy solution.

I have a bathroom washbasin with twin taps both connected to copper supply pipes via flexible tap connectors with iso valves. I changed the taps about 2 years ago, but at the time I used a freezing kit on the hot connection in order to change the tap and swap the connector for one with an iso, as I couldn't work out how to turn the hot supply off without draining the tank. Its a conventional open vented system.

One of the replacement taps seized completely a couple of weeks back, so I decided to take the opportunity to fit a pair of lever taps, which would be easier for a member of my family to use because she has problems with her grip due to arthritis. I managed to connect the cold supply without any problems, but on the hot side I've had trouble getting a watertight seal between the old tap connector and the new tap. It may be, therefore, that I'll have to renew the connector.

What I wanted to ask is whether there's a way to isolate the hot supply so I can change the tap connector without having to buy another freezing kit, and without draining the tank. I can see where the hot water supply pipe exits the top of the tank and goes down behind it to join the hot supply pipes at the bottom rear of the airing cupboard on their way to bathroom and kitchen, but there doesn't appear to be any isolating valve.

Thanks in advance.

 

[ianmcd]

post a pic of the isolating valves and a pic of your hot water cylinder

 

[therambler]

Assuming that you have a conventional system (not a combi boiler) the hot water cylinder is normally supplied from the header tank in the loft. If you make up a suitable plug and use it to block the water from exiting the header tank you should be able to drain off the pipe to the tap in question. With no water going into the hot water cylinder you shouldn't get any out as they normally work on a displacement arrangement.

While you're doing the tap replacement I'd strongly recommend that you install a flex hose and ball valve on the feed pipe to the tap, you can get them in any of the DIY stores. That way you can isolate just that tap the next time (there will be one). As a matter of course I always install this arrangement on any taps, cisterns etc. that I have to work on. Its so much simpler to just turn the ball valve with a screwdriver to isolate the tap etc. that you're working on.

 

[amfisted]

I've already fitted flexi connectors with iso valves, but the problem is that I'm not getting a watertight seal with the new tap, so if all else fails I may have to fit a new connector. Hence the need to isolate the hot water supply to the basin below the connector.

I'll check the header tank to see whether there's already a valve on the exit pipe, and if not I'll try your solution, thanks.

Will post pics tomorrow, hopefully.

 

[amfisted]

I've been doing a little extra reading about the topic, and have found a couple of posts on other forums where members asking a similar question have been advised to turn off the mains supply to stop the header tank from refilling, thereby cutting off the supply to hot taps by preventing displacement.

Would this work?

 

[ianmcd]

I've already fitted flexi connectors with iso valves, but the problem is that I'm not getting a watertight seal with the new tap, so if all else fails I may have to fit a new connector. Hence the need to isolate the hot water supply to the basin below the connector.

I'll check the header tank to see whether there's already a valve on the exit pipe, and if not I'll try your solution, thanks.

Will post pics tomorrow, hopefully.

just shut the iso valve on the flexi , that is what it is there for

 

[amfisted]

just shut the iso valve on the flexi , that is what it is there for

Yes, I know what its there for. I fitted it myself. ;0)

I'm obviously not making myself clear.

I'm trying to fit a new hot tap on an old flexi with iso, and unable so far to get a watertight seal between tap and connector. Thus I'm asking about ways to isolate the hot supply so that I can fit a new flexi.

 

[ianmcd]

where your hot water cylinder is there will be a pipe entering the bottom of the cylinder, it should have red handled gate valve on that pipe close that and open the hot tap until the water stops running

 

[Alec_t]

Have you investigated why you aren't getting a watertight connection to the tap? Usually there's a red-fibre washer to seal the joint. If so, renew the washer. Also, check for any burr/roughness/notch on the base of the tap threaded part.

 

[Tay7]

Renew washer but wet it first.

Or...

As has been said, you need to look at the bottom of the cylinder not the top. The cold feed from the header tank enters the bottom of the cylinder and pushes hot out the top via the head of pressure from gravity.

There may be a way of isolating the cold feed into the bottom of the cylinder either by a gate valve, an iso valve further up the pipework in the airing cupboard (maybe at shoulder height) or in the loft even further up the pipe nearer the tank. Bunging the outlet and tying up the ball valve from the header tank will also work. Either way, its the cold feed pipe into the bottom of the cylinder that needs isolating to stop it pushing hot out the top.

 

[amfisted]

I've remade the connection using a new washer stolen from a spare connector, and the leak between tap and flexi seems to have stopped.

However, I will carefully study the hot water cylinder and associated pipework in conjunction with the advice given above, so that in future I shouldn't have to ask the same question.

Much obliged to all for your responses.