cdb wrote:

> Personally I think local instantaneous heating not only saves
> electrickery but also reduces water used. The only time this would
> not be so in my opinion is if running a bath was required (will be in
> next years Olympics as a sport) and where constant high usage hot
> water is required.=20
>=20
> Reasons for assertion:=20
>=20
> Only heating the water that you actually use - so as kW's are charged
> in units of time, 5 minutes is less than the 30 or 40 minutes it
> takes to heat a large tank.=20
>=20
> Less than 500ml (3/4 pint) of water is 'wasted' between being cold
> and hot. assuming the system is installed at point of use.=20

The downside is that local instantaneous heating basically assumes
heating with electricity. (Using oil or gas for local heating is at
least inconvenient.) Heating with electricity is not only more expensive
in many places, but usually also less efficient (overall).

> Sadly they don't seem to be legal in OZ, especially now that it is
> mandated solar or heatpump systems can only be installed in
> Queensland.

If you factor in the efficiency of a heatpump/solar system, I don't
think that local instantaneous heating saves energy. It still saves
water, though.

There is the possibility of having a small backflow pipe with each hot
water pipe, inside the insulation, and force a small amount of flow at
all times, from the end of the hot water pipe back to the hot water
reservoir. This would of course increase the energy losses, but it would
also reduce the amount of water wasted. Has anybody experience with such
a system?

Gerhard
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.