On Sat, 15 May 2010 19:47:19 +0100, Tim Watts wrote:
On 15/05/10 19:34, zzzzzzzzzz wrote:
So you waste the water in the pipes either way. If you're washing by hand
(with hot water) you're wasting all the hot water needed to get the tap up to
temperature, plus the water needed to do the dishes. Seems like an even
stronger argument for a hot-water plumed dishwasher.
No, because 10m of 15mm dia pipe contains 1.7 l of water. A typical
model 60cm wide Miele dishawasher takes in 13l of water over several
fills over 1-1.5 hours.
Someone just said six gallons, total. Models differ somewhat, but dishwashers
use significantly less water than washing by hand.
If it takes 4 fills (I haven't counted) that's about 3l of water per
fill so half of that is cold either way and the central heating has to
heat that half just to waste it cooling in the pipe and the machine has
to heat the other half from cold effectively. So it's hardly worth
bothering with.
Why do you put your water heaters out in the street? Almost every house I've
seen (with this being a *dumb* exception) has the plumbing centralized. My
first house had a run of less than ten feet to every hot-water tap in the
house.
Things may be worse with a combi boiler that actually has to fire up to
produce hot water from cold mains - there's now pipework wastage and
cold coming from the boiler while it gets the heat exchanger warmed up.
There is a stonger argument for a washing machine having a hot fill as
they use around 55 litres of water for a wash - but that's something to
do with (supposedly) the modern detergents preferring to work from cold
with a gentle warm up in the machine.
Our washing machine is right underneath the water heater.