"John Aston" wrote in message
.. .

Ed Sirett wrote in message
news
On Wed, 06 Oct 2004 00:40:02 +0100, John Aston wrote:

snip

A question regarding an unvented domestic hot water system: Cambridge
Water
tested my incoming main supply and informed me that the pressure = 2.8
bar
and the flow rate = 25 litres per minute. Is this sufficiently high
for
an
unvented supply feeding a family home containing two power showers, a
bath,
five sinks, three toilets, a washing machine and a dishwasher?

snip

Given that you want to soften the water I strongly think that a pumped
storage cistern approach will be best.

Better than an accumulator?


I think Ed means a basement located tank with a pressure pump doing all the
house, hot and cold. I prefer the combination cylinder.

I'm really surprised that 2.8 bar
static on 32mm (25mm inside) MDPE pipe gives only 25lpm.
This implies that the supply in the road is somewhat restrictive.

I wonder if the water meter could be resticting the flow significantly.

They sometimes do. Make sure you have a full bore 1/4 turn stop cock.

Did the Water Company section in the road get replaced all the way to
the
main? or just to the meter? or just to the property boundary.

The 32mm MDPE pipe was laid by me from the water meter point at the
boundary
of my property to the main stopcock in my house (a distance of 45m).

How was the 25 lpm derived?

Unfortunately I wasn't present when the Cambridge Water engineer came to
measure the flow rate, so I don't know how the figure of 25 lpm was
derived.
My own test was very empirical - I switched off all water supplied to the
house and turned on the garden hose. The jet of water did not "feel" very
substantial, particularly if is to be shared among appliances.

The garden hose is usually at the end a run in 15 mm pipe running through
double check valve. If you can, take a large bore hose directly from the
stop cock and measure that. If it is substantially better then run 22mm to
any mains fed appliances.

The are all sorts of tanks for using the eaves and apex of roof spaces
if
that is an issue.

Thanks. I'll look around.