In an earlier contribution to this discussion,
Lobster wrote:

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Lobster wrote:

Anyway, I'm now considering biting the bullet and installing a
'proper' blue MDPE pipe, which means digging up the drive and
considerable expense/hassle, and so not something to be undertaken
lightly, and unless I'm 100% sure it's going to make a decent
difference to the water flow at the two shower heads. So my question
is, is there a way of finding out? How can I be certain that the
bottle-neck is caused by the length of water pipe under the drive,
or elsewhere (eg the yards of 15mm pipework inside the house, or
whether the water pressure out in the road is not that great in the
first place?)

You could install a pressure gauge close to your rising main, and
measure the static pressure with no appliances running. This would
be the same as the pressure out in the street. Then turn on all your
taps, and measure it again. The difference in pressure would
represent the pressure drop along your underground pipe.

Thanks for that. I'll need to equip myself with a gauge first; I
guess once I've made some measurements I'll be back here with the
numbers asking what the implications of the results are!

As a follow-up to this... the easiest way to attach a gauge close to
the rising main would clearly be via a hose to the drain cock
adjacent to the stop cock. Or would the innards of the valve
contribute too much to any pressure loss? Also, can anyone tell me
what sort of flexible piping you're meant to attach to these drain
cocks? I've often wondered in the past, while experiment
unsuccessfully with lengths of garden hose, which are just too large
and even with jubilee clips fitted, they leak badly.

Thanks
David

Screwfix do a pressure gauge for 30 quid (No. 10179) which has a 15mm
pushfit connection. I think if I were doing it, I'd make up an adapter with
a piece of 15mm pipe at one end and a 3/4"BSP female thread the other end.
It would then be easy to connect the gauge to an outside tap or washing
machine tap.

I don't think I'd use a drain tap - they're not intended to be opened when
the system is under pressure!
--
Cheers,
Set Square
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