Isolating hot water tap - Unvented system

[Dazzh]

Hi,

Once again I'm on looking for a bit of help.

My son has a leaking hot water bath tap. There are no isolation valve fitted to the tap, or indeed any in his house.

So my question is how do I isolate the tap to change the valve? It's on an unvented system. I checked the hot water cylinder. It has 2 gate valves, one at the very top of the cylinder controlling a single pipe and one tucked away under it which feeds various pipes. I've read there can be issues closing and opening gate valves to don't want to start messing about with the wrong ones.

My own heating is a combi boiler so I just turn off the mains to change a tap valve, easy. However wanted to check best way to isolate on an unvented system.

As ever all help and advice really appreciated.

Thanks.

 

[Mottie]

Surely you can turn off his mains too - even if it’s in the street?

 

[Dazzh]

Yes, can turn off his mains, stop cock in the kitchen. Is that's all that is required to stop the hot water from the tap?
I would have thought I would need to turn something off at the HW cylinder or it would continue to run until it drained off.

 

[JohnD]

what colour is the HW cylinder? (this is not a joke)

Is there anything in the loft?

 

[Dazzh]

Hi John,

Thanks for the reply

HW cylinder is white.
No tanks or anything in the loft. I think its what you call an S plan system.
There is a single pipe that comes up and goes directly into the very top of the cylinder with a red gate valve on it.
The cylinder is in an upstairs airing cupboard and is approx 1 1/2 ft off the floor, underneath it is all the port valves, pump etc. There is also another pipe going to the cylinder which enters it at the side near the bottom, it also has a red gate valve on it.

 

[JohnD]

then you can turn off the stop cock. Open a hot tap and water will briefly run out, then stop. The tap will not empty the cylinder.

 

[Dazzh]

Thanks John, appreciate your help and advice.