In an earlier contribution to this discussion,
Ian & Hilda Dedic wrote:

Hi guys,
I have a gravity fed hot water system from a normal hot tank ch in the
upstairs bedroom (a long way away from the kitchen tap)
and the hot water takes ages to run, what's more is there is not
enough pressure to let the new spray tap work properly. Cold water is
not a problem.

I assume that the cold comes straight off the mains, and so is at mains
pressure.

can I fit a small pump to increase the hot water pressure?

Yes.

If so where should I put it? I have two sinks one in the utility room
(ie the old kitchen) and one in my lovely new kitchen in the
extension.
The hot water stop valve turns all hot water to taps off, so if I put
it near there it would increase the pressure all round.

It depends where the stop valve is! If it's between the cold header tank and
the hot cylinder (as is often the case) *don't* put it there 'cos it will
pressurise the hot cylinder, which is *very* bad.

Are there any items I should be wary of with the increase in pressure
ie hot feed to washing machine, hot tank bulging? CH hot water system
becoming upset?

Put it close to the hot cylinder's hot *output* - then it won't pressurise
the cylinder but will boost *all* hot taps. It won't upset the primary
circuit used by the CH and by the coil inside the HW cylinder. It shouldn't
upset the washing machine - but you may have swap a low-pressure inlet
nozzle with a high pressure one. Read the washing machine manual!

what pump could I actually use?

You need a pump designed for this purpose - with a built-in flow-switch so
as to turn on as soon as you open a tap. It probably needs bronze internals
since it is dealing with constantly changing oxygenated water - unlike a
central heating pump which is simply circulating the *same* water (hopefully
containing corrosion inhibitor) all the time.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!