In today's Sunday Times there is an item about a company called Zenex.
Zenex has built a pre-heater for the cold water feed into combi
boilers which is
designed to extract the last "bits" of energy from the exhaust and
dump it into the cold feed to the HW feed.

When I looked for Zenex on this site, so as to check, all I found was
a lot of stuff in 2006 which was a tad dismissive. Lots of science,
pseudo or near-science about it.

3 - 4 years on, what are the real experiences?
Alpha have rites to the technology and have built an integrated unit.

It seems that the technology is a tad obvious but the value depends on
the cost benefit ratio.

Ideas... Comments.