Another know-it-all. Do a Google on groups and type in gfx. If you
did
that first you wouldn't nake such an idiot of yourself. There are some
Americans who have these installed and reported figures on them. The
average
temp rise is 17C. In effect it makes your cylinder bigger too. When
showering they are effective because you are heating the incoming cold
water
with waste water simultaneously.

Domestic applications have a far loger payback than commercial. Heavy
use
of waste water would make it feasible, in places sucj as hotels. Make
your
own, as in solar panels, and the payback is quite quick. See my post
on
making one.


So if you have a combi that gives 11 litres/min @:35C temp rise, then
having
one of these pre-heating the mains water to the combi will give and
extra
50% temperature rise. In effect making that 11 l/min to approx 17
litres/min


Its funny, but he's quite right.

NT