Isolating main hot downstairs tap on system boiler.

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I have a leak on the hot pipe in the wall in the kitchen. I have a system boiler with cylinder in bedroom. From what I can see there are 2 valve's by the cylinder. One valve which is on the pipe what feeds the cylinder from the header tank and another which is a gate valve on the bottom pipe by the cylinder. I am trying to leave the cylinder full but isolate the pipe to the kitchen so I can work on it . This way it will prevent me from dropping the full cylinder and possibly getting a airlock. I have shut the gate valve and then opened the downstairs tap but it is not isolating it. Am I missing something here ?[/b]
 
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A picture would help.
Normally the supply from the loft tank comes down and enters the tank at the bottom with a valve. That shuts water off to the whole cylinder.

Often there is one on the draw off (the pipe from the top of the cylinder to the tap) A vent pipe comes from the top of the cylinder and rises up without any valve or restriction to terminate over the tank. The draw off tees into this vent pipe and may have a valve on it that closes off just the hot taps.

If this turns off the water may run for a short time if you have other taps open till the pipe empties.

If the supply into the bottom of the tank is closed off water may run for a bit longer as the water in the vent pipe drains down.

Either way water will not drain further than the point that the draw off tees in above the cylinder.
 
That looks like the balancing valve on the domestic hot water return it will stop circulation on the hot water circuit heating the cylinder.

It is normally set by the installer to balance the system (not to be moved opps!) can you remember how far you had to turn it to off if possible you need to open it the same amount.

Too little and the boiler will overheat and keep shutting off, too much and the heating may be "robbed" by the hot water side. If you do open it more than is was that will be better than not enough all that will happen is the heating will be slow to heat up while the hot water is heating up too.
 
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The gate valve you are closing is the return from the cylinder this used as a balancing valve and will not isolate the hot water.
There should be another one which is usually a little higher than the cylinder which should isolate the hot water.
Failing that you will have to tie up the ball valve in the CWSC.
 
The gate valve you are closing is the return from the cylinder this used as a balancing valve and will not isolate the hot water.
There should be another one which is usually a little higher than the cylinder which should isolate the hot water.
Failing that you will have to tie up the ball valve in the CWSC.

Thanks for reply. there is a valve abit higher than the cylinder . I thought this was to stop the cylinder filling up then you can drop it via a tap.

Bit confused what tieing up the ball valve will do in the header tank. If I do this then do you mean drop the water out the both tanks ?

If so I know I have a isolation on the header tank so no need to tie up the valve but dropping these is what I am trying to avoid.

Sorry if I have gone off on one and this is not what you intend .
 
Don't know if the tap above will turn off the cylinder it will usually go in at the bottom on the other side to the one in the photo, then as you say the taps can be used to drain the cylinder, it will however take a while to sop running.
 
Don't know if the tap above will turn off the cylinder it will usually go in at the bottom on the other side to the one in the photo, then as you say the taps can be used to drain the cylinder, it will however take a while to sop running.

I know but I am trying to keep cylinder full so I do not get a airlock as these are a pain.
 
The cylinder will remain full whichever way you isolate the hot.
If you isolate the cold to the CWSC and open the taps the water will stop running when the CWSC is empty but the cylinder will still be full.
 
If the cold tank is isolated then I open the both taps will this not empty the both cylinders but not re - fill as the cold tank is isolated which also feeds the hot cylinder ?
 
Water cannot drain any lower than the point where it is drained from, the draw off (tap supply) is taken from above the cylinder that tees in above the cylinder that is the only level it can drain to.

To drain the cylinder you would need to open the drain tap on the bottom of the cylinder usually on the entry point of the cold feed hidden away in an inaccessible point at the back!

You cannot drain the water from the cylinder through the hot taps ;)
 
Water cannot drain any lower than the point where it is drained from, the draw off (tap supply) is taken from above the cylinder that tees in above the cylinder that is the only level it can drain to.

To drain the cylinder you would need to open the drain tap on the bottom of the cylinder usually on the entry point of the cold feed hidden away in an inaccessible point at the back!

You cannot drain the water from the cylinder through the hot taps ;)

Ok thanks I have a look for another tap then as is the feed from the cold tanks the other is a balancing gate valve so to isolate there must be another one hidden .Is this correct ?

Thanks for help
 
Have a look at the link.

http://www.muswell-hill.com/foxandco/pages/boilertypes.htm

The pipe on the lower right of the picture connected to the coil in the cylinder is the one in your picture that is the hot water heating circuit, as said that should not be tampered with.

The one on the left with "Drain Cock" by it is the cold feed from the tank (cistern) to the cylinder that is the pipe you need to follow and find a tap on to shut off the water.
 
Have a look at the link.

http://www.muswell-hill.com/foxandco/pages/boilertypes.htm

The pipe on the lower right of the picture connected to the coil in the cylinder is the one in your picture that is the hot water heating circuit, as said that should not be tampered with.

The one on the left with "Drain Cock" by it is the cold feed from the tank (cistern) to the cylinder that is the pipe you need to follow and find a tap on to shut off the water.

I can find cold feed from cistern shut off but wouldnt the cylinder still me full but not re - fill. Do I not need to find on shut on the domestic on water feed on the image ?
 
You want to repair the pipe from the cylinder to the tap.

You want to drain water from that bit.

Turn off the water going into the cylinder.

Open all the hot taps, the water will drain out of the pipe all the way up to the open vent in the loft.

It will only drain as far as the top of the cylinder.

Repair the pipe.

Turn the water back on it will flow into the cylinder and push the water that has been sitting in the cylinder out up the open vent and along to the taps which you then close one by one as the water comes through.

Sit back make a cup of tea and give yourself a pat on the back ;)
 

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