"John Law" wrote in message
...
Hi all

The hot water pressure in our kitchen is awful: we have to wait maybe 90
secs for the really hot water to come through from the tank upstairs.
On the other hand, it takes a few seconds only for the water to come to
the upstairs basin.

So far, so fairly bleeding obvious. (Additionally: the kitchen tap is
one of those fancy pull lever up and swing left or right for hot or
cold, on a long flexible pipe so you can hose the dishes, and with a
press-button spray system; and goodness knows (I've forgotten) what
convolutions the feed pipe goes through on its way from upstairs to
down.)

My question: what would The Panel suggest, as a means of improving
reaction time downstairs? Get rid of the fancy tap? Look at and
improve the route? or could I perhaps replace the standard 15mm pipe
with 22mm pipe?

I'll be grateful for any suggestions -- [for those who saw the thread: I
am no Jackie].

So far no one has really attacked the question with any great logic. The
time it takes for hot water to come through should be a function of the flow
rate and the volume in the pipe between the cylinder and the tap. So the
first stage is to measure the flow rate. My own hot water tap in the sink
fills a pint glass in about 4 seconds or 7 seconds per litre. The cold tap
at mains pressure does it in half that. So what is the flow rate from your
own tap? Can you live with that flow rate or does it take too long to fill
the sink? If yes then you need a better tap anyway, or as you have been
told, one that is suitable for non-mains pressure water.

Step 2 is the volume of water between the cylinder and the sink. 15mm pipe
has an i/d of 13.6mm which equates to 145cc per metre or 1 litre every 7
metres.

22mm pipe has an i/d of 20.2mm which equates to 320cc per metre or 1 litre
every 3 metres.

So measure the length of pipe run to the sink and note the pipe diameter.
Work out the pipe volume. Does the flow rate and pipe volume equate to the
90 seconds it takes for hot water to come through? It would take a very long
pipe run and a truly awful tap to account for 90 seconds of cold flow.
Normally you'd expect it to be under 15 seconds.

There are only three solutions. Reduce the pipe diameter, reduce the pipe
length, increase the flow rate of the tap.
--
Dave Baker
Puma Race Engines
www.pumaracing.co.uk
Camp USA engineer minces about for high performance specialist (4,4,7)