On Mon, 07 Aug 2006 00:09:05 +0100, Doctor Drivel wrote:


"John Stumbles" wrote in message
news

This works and provides excellent recovery but you do need a gravity
(not sealed/unvented) primary.

???

What do you mean '???' ?

If the primary is unvented you have an unvented hot water cylinder of 15l
requiring all the appropriate safety controls. This rapidly gets outside
DIY.