On Mon, 20 Feb 2006 21:06:58 +0000, Ed Sirett wrote:

On Mon, 20 Feb 2006 12:25:01 +0000, Dave Plowman (News) wrote:

In article ,
David WE Roberts wrote:
I have done a rough flow rate calculation using the cold tap at the bath
- I calibrated an orange B&Q builders bucket at 10 litres up to the
spout, then counted 'one and two' etc. as I didn't have two extra hands
to work the stop watch. It takes about 10 seconds to fill a 10 litre
bucket including the turn on time so flow should be at least 60 litres
per minute.

Sounds like that's coming off the header tank.

Thanks Dave, I'd missed that when I replied earlier.
The OP needs to measure the flow rate of cold at the kitchen sink, he'll
need 20litres/min to fit the Alpha CD50.

Hmmm....I'm pretty sure that the cold water is coming from the mains, not
the header tank,but I will check.
If I am getting this pressure from the header tank (around 8' head from
the tank (top of water level) to the bath tap then this is pretty
impressive.
I thought that in general cold should come from the mains (therefore
suitable for drinking), and also there seems no point in taking cold water
from the tank as it reduces the amount available for the hot tap.

You obviously need tank fed for applications such as a power shower where
balanced input pressures are needed.
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{puff, pant}
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Yep - mains pressure.
Checks:
(1) I turned the hot tap on and ran it for about 5 seconds. I could hear
the cistern in the loft start to fill. This ran on for a bit after I
turned the hot tap off.
(2) I turned the cold tap on. About twice the perceived pressure, and no
cistern filling sounds during or after running the cold tap.

I used the bath tap as a test because
(a) I knew there was restricted flow from the kitchen tap
(b) From looking at visible pipes I think that the bath is fed by 3/4"
cold mains as opposed to the 15mm to the kitchen tap, thus giving a better
measure of potential flow.

Still, worthwhile double checking.

Cheers

Dave R