Hot cylinder connections

[dc1977uk]

Hi All,
Hoping someone can help me in working out how to stop the hot water from my hot water cylinder as there is no valve to do so from the top of the boiler.
Also what are the valves 'A', 'B', 'C', 'D' & 'E'?
The valve at the bottom of the boiler is seized, but I am hoping 'A' might be the cold water feed from the cold tank in the loft?
There is a an isolator thats feeding the hot water cylinder at the bottom which is seized (open) and I dare not touch - assume this is the cold feed in?

All I want to do is exchange a sink in the cloakroom but the hot feed has no isolator!
By the way this is a gravity system with a cold tank in the loft, hot cylinder (pictured) and a standard boiler in the kitchen.

Thanks!
Dan

 

[exedon2]

First there should not be any sort of valve on hot out of cylinder.
The valve your after is probably the one marked A I think you will find that drops behind cylinder and connects near bottom. B & C probably shower feeds
D is a 3 port motorised valve E heating pump.
I would personally be very careful using any of the valves they have a tendency to snap internally.
The seized valve is on cylinder return probably to throttle it down.

 

[SJB060685]

As above most likely valve A.
Just climb into the loft and either isolate cold fill into header tank if there is a valve or tie the ball valve up, alternatively shut the cold mains stopcock, you will have to drop some water out until you can replace the unit.

 

[dc1977uk]

Thanks all.
You were correct, A was the cold feed and isolating that stopped the hot water, although I had to open the kitchen hot tap to leak away the residue flow so as to keep the cloak room hot from dripping.