My house is fully plumbed on high pressure water; ie no cold water storage
tank and an unvented HW cylinder. It provides a pretty flow of water at the
taps/shower, but the shower is definitely affected if another tap is run or
the dishwasher fires up. I'm shortly going to install a second shower to
cope with the demands of a growing family (ie, a 13-y-o daughter) and am
concerned that if both showers are run together (which would be the whole
idea), then neither will be satisfactory.

The plumber who fitted our unvented system a few years ago did express
concern about our incoming watermain, and said that we might need to renew
it if the pressure was inadequate. I can't remember what bore it is where
it runs underground 25 yards out to the road (but it was partly exposed at
the time, hence the plumber's remark), but what comes up through the kitchen
floor is just 15mm copper).

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?)

Thanks for any pointers
David

In an earlier contribution to this discussion,
Lobster wrote:

My house is fully plumbed on high pressure water; ie no cold water
storage tank and an unvented HW cylinder. It provides a pretty flow
of water at the taps/shower, but the shower is definitely affected if
another tap is run or the dishwasher fires up. I'm shortly going to
install a second shower to cope with the demands of a growing family
(ie, a 13-y-o daughter) and am concerned that if both showers are
run together (which would be the whole idea), then neither will be
satisfactory.

The plumber who fitted our unvented system a few years ago did express
concern about our incoming watermain, and said that we might need to
renew it if the pressure was inadequate. I can't remember what bore
it is where it runs underground 25 yards out to the road (but it was
partly exposed at the time, hence the plumber's remark), but what
comes up through the kitchen floor is just 15mm copper).

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?)

Thanks for any pointers
David

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.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"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

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
______
Please reply to newsgroup. Reply address is invalid.

I can definitely confirm that replacing your old main which terminates in 15 mm
copper
with 25mm MDPE wil very substantially increase your flow rate whatever the
pressure is.
I recently replaced my old steel incoming pipe which was about the same ID as
15mm copper, and old and internally corroded, with 25mm MDPE and the two ran
"side
by side" for a while, with valves to allow the house to take via the old or the
new.

The max flow rate into the bath with both bath taps running, filling a bucket,
was 13 litres a minute on the old incoming pipe and a massive 45 litres a
minute on the new ! !
I fact it was more, as a fair amount was spraying around the bucket the force /
flow
rate was so good! - I had also replumbed everywhere with 22mm copper as far as
possible
so pressure drop was minimised in the house - anyway, shower now gave a flow
rate of
some 20 litres a minute which was too much ( on a meter now) so fitted the
smaller bore
shower hose which dropped it a bit to some 15 litres a minute, which is still
good!
If you heat water on demand (combi) I would say you also need to consider
whether the boiler
will cope with two showers running ? Mine was a 105,000 BTU , and I like
cooler, high flow
showers - flow reduces in winter and / or with hotter showers.

Go for a 25 or 32 mm re-plumb and keep the bore big in the house as far as
possible.
The water company may charge more for larger pipe sizes !

Nick

"Lobster" wrote in message
news
My house is fully plumbed on high pressure water; ie no cold water storage
tank and an unvented HW cylinder. It provides a pretty flow of water at
the
taps/shower, but the shower is definitely affected if another tap is run
or
the dishwasher fires up. I'm shortly going to install a second shower to
cope with the demands of a growing family (ie, a 13-y-o daughter) and am
concerned that if both showers are run together (which would be the whole
idea), then neither will be satisfactory.

The plumber who fitted our unvented system a few years ago did express
concern about our incoming watermain, and said that we might need to renew
it if the pressure was inadequate. I can't remember what bore it is where
it runs underground 25 yards out to the road (but it was partly exposed at
the time, hence the plumber's remark), but what comes up through the
kitchen
floor is just 15mm copper).

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?)

Thanks for any pointers
David

You need 22mm from the stop cock to the cylinder and also a full bore stop
cock. If either of these is not done, get it done, and then see if the
performance improves. the plumber is probably right in the mains being too,
small, but you still those two points seen to.

nick smith wrote:

I can definitely confirm that replacing your old main which terminates in 15 mm
copper
with 25mm MDPE wil very substantially increase your flow rate whatever the
pressure is.
I recently replaced my old steel incoming pipe which was about the same ID as
15mm copper, and old and internally corroded, with 25mm MDPE and the two ran
"side
by side" for a while, with valves to allow the house to take via the old or the
new.

The max flow rate into the bath with both bath taps running, filling a bucket,
was 13 litres a minute on the old incoming pipe and a massive 45 litres a
minute on the new ! !
I fact it was more, as a fair amount was spraying around the bucket the force /
flow
rate was so good! - I had also replumbed everywhere with 22mm copper as far as
possible
so pressure drop was minimised in the house - anyway, shower now gave a flow
rate of
some 20 litres a minute which was too much ( on a meter now) so fitted the
smaller bore
shower hose which dropped it a bit to some 15 litres a minute, which is still
good!
If you heat water on demand (combi) I would say you also need to consider
whether the boiler
will cope with two showers running ? Mine was a 105,000 BTU , and I like
cooler, high flow
showers - flow reduces in winter and / or with hotter showers.

Go for a 25 or 32 mm re-plumb and keep the bore big in the house as far as
possible.
The water company may charge more for larger pipe sizes !

Nick


Unlike Nick I replaced lead pipe with 25mm MPDE, it made no difference
that I could tell. I must say I am somewhat confused by flow rates,
with MPDE an insert is fitted at the joints to reinforce, these have a
relatively small hole compared to the pipe, so surely that is the same
as fitting a small pipe?

--
Please do not reply by Email, as all
emails to this address are automatically deleted.

"Lobster" wrote in message
news
SNIP

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?)


"If" the main under the road is of adequate size then a drop in flow must be
related to your supply branch pipework. However if you and your neighbours
are being supplied by a somewhat smaller street main then a pressure loss
due in part to the resistance of the street main will affect you "and" your
close neighbours. Try asking your next door neighbour if turning on your
taps can be noticed in the flow rate available in their house too. A
practical test may be needed.
The most likely scenario is the loss occurs in your suply branch but if you
are at the end of a street or live in a terrace then the shared supply may
be the problem.

"John" wrote in message
...

"Lobster" wrote in message
news
SNIP

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?)


"If" the main under the road is of adequate size then a drop in flow must
be
related to your supply branch pipework. However if you and your neighbours
are being supplied by a somewhat smaller street main then a pressure loss
due in part to the resistance of the street main will affect you "and"
your
close neighbours. Try asking your next door neighbour if turning on your
taps can be noticed in the flow rate available in their house too. A
practical test may be needed.
The most likely scenario is the loss occurs in your suply branch but if
you
are at the end of a street or live in a terrace then the shared supply may
be the problem.

If the steet main is too small, then foitt a larger supply pipe as water
takes the least rsistance. Also go down the strett and turn down the water
cocks of all the other homes that have cold tank system (don't let them
know). They don't need full rate, this then favours your house, which does.

On Mon, 30 Aug 2004 12:15:14 +0100, "IMM" wrote:



If the steet main is too small, then foitt a larger supply pipe as water
takes the least rsistance. Also go down the strett and turn down the water
cocks of all the other homes that have cold tank system (don't let them
know). They don't need full rate, this then favours your house, which does.



One of your better ones.

How would you suggest that this clandestine cock turning could be
accomplished without being spotted?

Visions of IMM, dressed like the Sandeman Port man; sliding through
the streets in the night time fog looking for houses with overflows
from the loft and turning down their water supply.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Mon, 30 Aug 2004 12:15:14 +0100, "IMM" wrote:

If the steet main is too small, then foitt a larger supply pipe as water
takes the least rsistance. Also go down the strett and turn down the
water
cocks of all the other homes that have cold tank system (don't let them
know). They don't need full rate, this then favours your house, which
does.

One of your better ones.

Thank you.

How would you suggest that this clandestine cock turning could be
accomplished without being spotted?

During the night. I know someone who did this with his neighbours either
side. he just opened the lids and screwed the cocks half down. They didn't
know the difference and his system didn't have fluctuations after.

Visions of IMM, dressed like the Sandeman Port man; sliding through
the streets in the night time fog looking for houses with overflows
from the loft and turning down their water supply.