"Tony Bryer" wrote in message
...
On Mon, 20 Feb 2006 14:14:16 -0000 Doctor Drivel wrote :
Firstly it "saves" water and reduces the water bill. The longer the
dead-leg DHW pipe runs the more the saving.

I don't deny the amenity value, but would challenge you to show how
this will save money.

The last time I checked metered water was 90p per cubic metre (1000
litres): assume it's doubled since.

Actually ....; even with the base price quoted it is (approximately)
double : 'they' sting you for the water supplied _and_ for the
waste removed [my supplier 'allows' five percent off the quantity
presumably 'they' reckon I perspire and/or urinate outside the house!]


10m of 15mm copper tube contains
about 1/8 litre - 8000 draw-offs saves £1.80. If you can do your
timer, return leg and pump for £100 you'd be doing well. So by the
time you get to 450,000 draw-offs you'll have recovered the
installation cost by the water saved. It's just that in the meantime
those pipes have continuously been losing expensive heat for x hours a
day instead of just once between each use. Yes you'd save money on
water more quickly on a longer dead leg but then you'd be spending
even more keeping the water hot - Google wouldn't quickly give me a
figure for the heat loss from an insulated copper pipe.


Concur with the economics.argument Saving water while wasting heat
isn't too good.

--

Brian