"Kevsy1" wrote in news:1128242615.721875.124780
@g44g2000cwa.googlegroups.com:

The 'unusual' fixing I mentioned above is a compression gate valve
(BS5154) but dows not have the red turning dial on it! Just the loose
nut at the end. Turning this just makes the nut go up and down the
thread. (http://www.gofixit.co.uk/en-gb/dept_1289.html)

Your hot water is driven, (in a vented system) by water from the cold
tank above entering the cylinder and pushing hot water out of the top.

This is where your handle-less gate valve is.

It sounds buggered, it certainly needs a handle.

To replace it you need to empty your cold water tank by turning off your
stopcock, and opeing the lowest tap in the house. (and any others for
speed)

You can then remove the gate valve by unscrewing the nuts, and fit a new
one.

It can be a good idea to leave the old nuts and olives(little collars) on
the pipe and just use the new body. If you're a wuss you can smear Fernox
LS-X on the olive to make sure of a watertight joint with the new body,
also a smear of grease on the threads acn help.

HTH

mike