"Andy Burns" wrote in message
...
On 18/11/2007 15:47, John wrote:

Have you actually done this, i.e. EMPTIED the hot water cylinder via a
cold tap?

You shouldn't be able to /empty/ your hot water cylinder through a hot
tap, let a lone a cold tap.

I must ask why you think this, If the main stoptap into the house is turned
off as the OP stated and a hot tap is opened then the cylinder would
eventually empty (apart from the dregs in the bottom), unless my
understanding of gravity is wrong!

John