In article , Doctor Drivel wrote:

G3:
http://www.opsi.gov.uk/si/si2000/20002531.htm

"Requirement G3 does not apply to -

(a) a hot water storage system that has a storage vessel with a capacity
of 15 litres or less;

Interesting potential loophole in that it doesn't say has _only_ a storage
vessel with a capacity of 15 litres of less.....