On Mar 2, 8:56*am, Chris J Dixon wrote:
Andy Burns wrote:
That'll leave the hot cylinder full, look for a drain point at the base
of the cylinder where the cold enters, or failing that you may need to
undo the threaded connection at the top where the hot exits, and syphon
it with a hose.

Whatever you do, don't close the inlet valve to the hot tank, and
open the kitchen hot tap. This can be an effective, but costly,
way to demonstrate the power of atmospheric pressure.

Rubbish! I've done that lots of times.

The hot water take off is at the top of the cylinder, with an overflow
up to the header tank. All that happens is that the pipes to the taps
drain down and air is sucked down the overflow to replace the water.
The cyclinder is left full of water, as other have pointed out.

MBQ