Isolate Water

[kevinsmbuk]

I have a system CH boiler and a hot water cylinder, there is a cold water tank in the loft.

I want to remove the bath unit and sink unit from the upstairs bathroom, what would I need to do to isolate the hot and cold water supplies upstairs?

I don't have isolation valves but plan to fit them.

Thanks

 

[Blagard]

The chances are your cold water taps are fed from the mains , so you need to turn off the mains stopcock.

Your hot water is fed by the cold water from the feed tank replacing the hot water you draw off, so you either have to turn off the gate valve on the feed pipe that goes into the bottom of your cylinder, of if that is not working (A common issue with gate valves) you need to draw off the hot water to empty the feed tank while the stop tap is off.

Then fit isolation valves to save the hassle in the future.

Your boiler/central heating is not affected by the above and can continue to be used.

 

[kevinsmbuk]

Hi thanks that is really helpful, the house is 1980's so you think that it would all be mains fed upstairs for the cold?

To give you a bit more info on the system here is a pic of the airing cupboard



and am I right in thinking that this is the cold water stopcock? below fuseboard

 

[Blagard]

To check that the cold upstairs is all mains fed just turn off the stop cock.

Then you will only be able to run a litre or two out of mains fed pipes as just the water in the pipes is released.

The cold feed tank feed to the cylinder seems out of the picture. I would expect it to be connected to your cylinder on the bottom right hand side opposite the coil primaries you can see on the left. Trace that right hand connection back and you should find a gate valve that may or may not work to turn off the hot water.

The gate valve in the lower left of the cylinder is set by the heating engineer to regulate the flow though the cylinder coil so leave that valve alone.

The system appears to be a Y plan with a three port valve that controls flow into the cylinder coil and heating circuit. The three port valve will be HW only in its rest position. Your programmer will move the internal ball to mid position for CH and HW. And finally if you call for CH only the ball in the valve will move all the way over to block the HW circuit. The cylinder thermostat on the lower left of the cylinder will turn off the hot water heating via the three port valve when your hot water reaches the set temperature.

The valve on the left above the shelf is difficult to see for size but if it is on a 22mm pipe I would expect it to be the cold water feed to your cylinder. So it would have to go across at low level to the right side of the cylinder before connecting into it. If I am correct that valve will shut off your hot water. But as noted, those valves are notorious for failing because they are so rarely used they seize up or fail to shut the supply off 100%.

 

[kevinsmbuk]

thanks so much for all your help it is appreciated, would you mind if I took a couple of extra pics when we complete our purchase on the house, it is imminent now just to 100% clarify what they are?

If the gate valve did fail which sounds fairly likely then is there another way of shutting off the hot water?

 

[Blagard]

<snipped>If the gate valve did fail which sounds fairly likely then is there another way of shutting off the hot water?

Not really - You would have to turn off the cold water supply to the feed tank and then drain it off (the cylinder remains full). After that you could replace the gate valve ideally with one of these: http://www.screwfix.com/p/pegler-ball-valve-blue-22mm/18343
They are more reliable!

 

[chantelle]

<snipped>If the gate valve did fail which sounds fairly likely then is there another way of shutting off the hot water?

Not really - You would have to turn off the cold water supply to the feed tank and then drain it off (the cylinder remains full). After that you could replace the gate valve ideally with one of these: http://www.screwfix.com/p/pegler-ball-valve-blue-22mm/18343
They are more reliable!

Wrong...You can climb up to your loft, go to your header tank and bung the outlet to your hot water cylinder, use a carrot!! run off your hot water taps..Bingo,no need to turn off your mains at all.

P.S. If he drains down his header tank how can his cylinder remain full.

 

[Blagard]

<snipped>If the gate valve did fail which sounds fairly likely then is there another way of shutting off the hot water?

Not really - You would have to turn off the cold water supply to the feed tank and then drain it off (the cylinder remains full). After that you could replace the gate valve ideally with one of these: http://www.screwfix.com/p/pegler-ball-valve-blue-22mm/18343
They are more reliable!

Wrong...You can climb up to your loft, go to your header tank and bung the outlet to your hot water cylinder, use a carrot!! run off your hot water taps..Bingo,no need to turn off your mains at all.

I would not advise the OP to do that, as anything that could break such as your suggestion could end up obstructing the pipework. While a suitable "bung" would do as you say it would be quicker for most DIY'ers to simply turn off the stopcock and run the tank dry.

 

[chantelle]

So how do you drain the header tank whilst leaving a full cylinder noob? You should change your name to Bullsh**ter.

 

[Blagard]

So how do you drain the header tank whilst leaving a full cylinder noob? You should change your name to Bullsh**ter.

Oh my! - You really didn't know that the water only flows through the cylinder when you open the hot tap. You seriously think the cylinder becomes empty! Your hot water will stop flowing when the header tank is dry not when the cylinder is empty

Oh - Get some of these - better than carrots!
http://www.screwfix.com/p/6-nylon-drain-plugs/81203

 

[chantelle]

How do you drain the header tank,that`s the question. Tell me.Google it just like you have the bungs,take your time,

To drain the header tank you have to empty the hot water cylinder, Muppet!

 

[Blagard]

How do you drain the header tank,that`s the question. Tell me.

Just read the second post

 

[chantelle]

You don`t know what I mean because you are neither a plumber or gas engineer,you`re busted Muppet!

 

[sooey]

chantelle you're a t*t, just like bamber was. hmmmmm

 

[kevinsmbuk]

Guys I appreciate the help, but there is no need for flaming.

I want to make sure I know all risks, so I dont flood the house!!!

Will an isolation valve hold back the water as good as a push fit end cap?