On 31/08/2012 15:49, Tim+ wrote:

No access panels. I think the main problem is that there is no separate
drain point and the lowest accessible point to drain it is the cold
water inlet which is about 18" up the side. I suspect the only way to
do this might be to syphon it down with a hosepipe inserted in the top
but that's going to involve disturbing quite a lot of soldered pipework.

There's no immersion heater?