In article ,
GB wrote:
You only need to cut off the cold supply from the header tank and drop
the water level down to the level of the immersion flange - usually on
the top.

I'll pretty much empty it anyway. The last thing I need is the tank
splitting and deluging very hot water.

Run it out via the taps? It will then be replaced with cold. There may be
less risk of damage to the cylinder and pipes if it's full of water - the
extra mass will help stop it moving.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman London SW
To e-mail, change noise into sound.