Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help diagnose
the location of the pressure drop (see original thread below

http://tinyurl.com/65xgo

Finally(!), I've got around to buying a gauge, and have put it to use.
There's a threaded outside tap very close to the stopcock, so I was able
to attach the gauge there.

Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar

All pressures measure at the outside tap.

Now, I'm still not clear whether this helps. Presumably, if the
pressure had stayed at 3.9 bar under all 4 test conditions, that would
have told me that my incoming pressure was OK, and that the restriction
was inside the house, right? But these results would seem to be
intermediate, so I'm not sure how much benefit there would be if I went
ahead and had the new MDPE pipe fitted?

Any thoughts, or any other diagnostic measurements I should make? :-)

Thanks
David

Lobster wrote:
Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help diagnose
the location of the pressure drop (see original thread below
snip
Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar

Right.
So, (approximately) if you were to cut the pipe immediately after the
stopcock, it'd read 0 bar.
With every tap/... in the house running, about half the pressure loss is in
the inlet, half in the house.
Increasing the bore of the pipes in the house, and the taps will significantly
increase your flow.
Is the house one or two stories?

Ian Stirling wrote:
Lobster wrote:

Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help diagnose
the location of the pressure drop (see original thread below

snip

Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar


Right.
So, (approximately) if you were to cut the pipe immediately after the
stopcock, it'd read 0 bar.
With every tap/... in the house running, about half the pressure loss is in
the inlet, half in the house.
Increasing the bore of the pipes in the house, and the taps will significantly
increase your flow.

Thanks. So are you saying that you reckon increasing the bore of the
pipes inside the house would have the same effect as renewing the
incoming pipe, and that presumably these effects would be additive?
Neither would be very easily accomplished, all the same, mainly due to
the geometry of the house. It's the shower that's the issue, so which
pipes should I be looking at inside: between HW cylinder and shower?
Stopcock and HW cylinder? Stopcock and shower? All the above?(!)

Is the house one or two stories?

Two.

Thanks
David

Lobster wrote:
Ian Stirling wrote:
Lobster wrote:

Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help diagnose
the location of the pressure drop (see original thread below

snip

Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar


Right.
So, (approximately) if you were to cut the pipe immediately after the
stopcock, it'd read 0 bar.
With every tap/... in the house running, about half the pressure loss is in
the inlet, half in the house.
Increasing the bore of the pipes in the house, and the taps will significantly
increase your flow.

Thanks. So are you saying that you reckon increasing the bore of the
pipes inside the house would have the same effect as renewing the
incoming pipe, and that presumably these effects would be additive?
Neither would be very easily accomplished, all the same, mainly due to
the geometry of the house. It's the shower that's the issue, so which
pipes should I be looking at inside: between HW cylinder and shower?
Stopcock and HW cylinder? Stopcock and shower? All the above?(!)

Is the house one or two stories?

Two.

Ok.
Part of the problem is that it's two stories, the shower will see at best
0.4 bar less than a tap in the lower story.

Does the heating come from a combi boiler, or do you have a header tank?

Another test - possibly not needing the boiler.
Does a tap downstairs cause the same problem as an equal volume of water/
minute drawn from an upstairs tap?

If not, this might indicate that there is some constriction
in the pipe upstairs.

"Ian Stirling" wrote in message
...
Lobster wrote:
Ian Stirling wrote:
Lobster wrote:

Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming
water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help diagnose
the location of the pressure drop (see original thread below

snip

Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar


Right.
So, (approximately) if you were to cut the pipe immediately after the
stopcock, it'd read 0 bar.
With every tap/... in the house running, about half the pressure loss
is in
the inlet, half in the house.
Increasing the bore of the pipes in the house, and the taps will
significantly
increase your flow.

Thanks. So are you saying that you reckon increasing the bore of the
pipes inside the house would have the same effect as renewing the
incoming pipe, and that presumably these effects would be additive?
Neither would be very easily accomplished, all the same, mainly due to
the geometry of the house. It's the shower that's the issue, so which
pipes should I be looking at inside: between HW cylinder and shower?
Stopcock and HW cylinder? Stopcock and shower? All the above?(!)

Is the house one or two stories?

Two.

Ok.
Part of the problem is that it's two stories, the shower will see at best
0.4 bar less than a tap in the lower story.

Does the heating come

He said he had an unvented cylinder.

Before digging the ground up, I would get the pipes inside right first.

1. Install a full bore stop cock.
2. Have a dedicated 22mm pipe directly to the unvented cylinder.
3. Tee off at the stop cock and run to all cold supplies in the house on a
dedicated cold pipe.
4. Take the cold of the shower from the cylinder cold feed line, just
before it enters the cylinder.

If that sorts it then all is fine. If there is still problems replace the
mains pipe. Either way the internal pipes need sorting, so get them done
first.








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"Doctor Evil" wrote in message
...

"Ian Stirling" wrote in message
...
Lobster wrote:
Ian Stirling wrote:
Lobster wrote:

Hi all

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming
water
main with a modern wide-bore MDPE affair, specifically to prevent my
shower pressure from being so badly affected by other water outlets in
the house (it's all fully mains pressure, with an unvented HW system).
I was advised that the best course of action was to take some water
pressure measurements close to the stopcock, which should help
diagnose
the location of the pressure drop (see original thread below

snip

Here's some data:

a) Static pressure, no water flowing: 3.9 bar
(Flow rate measured at kitchen sink, no other water running: 20 L/min)

b) Shower running (nothing else): 3.8 bar

c) Shower running, plus bathroom sink tap and toilet flushing - causes
severe reduction in shower flow rate: 2.7 bar

d) Every tap/shower in the house running - causes shower to stop
completely: 1.8 bar


Right.
So, (approximately) if you were to cut the pipe immediately after the
stopcock, it'd read 0 bar.
With every tap/... in the house running, about half the pressure loss
is in
the inlet, half in the house.
Increasing the bore of the pipes in the house, and the taps will
significantly
increase your flow.

Thanks. So are you saying that you reckon increasing the bore of the
pipes inside the house would have the same effect as renewing the
incoming pipe, and that presumably these effects would be additive?
Neither would be very easily accomplished, all the same, mainly due to
the geometry of the house. It's the shower that's the issue, so which
pipes should I be looking at inside: between HW cylinder and shower?
Stopcock and HW cylinder? Stopcock and shower? All the above?(!)

Is the house one or two stories?

Two.

Ok.
Part of the problem is that it's two stories, the shower will see at best
0.4 bar less than a tap in the lower story.

Does the heating come

He said he had an unvented cylinder.

Before digging the ground up, I would get the pipes inside right first.

1. Install a full bore stop cock.
2. Have a dedicated 22mm pipe directly to the unvented cylinder.
3. Tee off at the stop cock and run to all cold supplies in the house on
a
dedicated cold pipe.
4. Take the cold of the shower from the cylinder cold feed line, just
before it enters the cylinder.

If that sorts it then all is fine. If there is still problems replace the
mains pipe. Either way the internal pipes need sorting, so get them done
first.


Check the isolation valves bewteen the pressure reduction valve and the
cylinder, sometimes these are not full bore, or are part turned off. Try
checking that that toilets and the cold side of the kitchen sink are not fed
from the pressure reduction valve. Check the strainer in the pressure
control valve is it furred up.

James Salisbury wrote:
"Doctor Evil" wrote in message
...

Lobster wrote:

I posted a query here a few months ago asking whether it was likely to
be worth my while biting the bullet and replacing the old incoming water
main with a modern wide-bore MDPE affair

Before digging the ground up, I would get the pipes inside right first.

1. Install a full bore stop cock.
2. Have a dedicated 22mm pipe directly to the unvented cylinder.
3. Tee off at the stop cock and run to all cold supplies in the house on a dedicated cold pipe.
4. Take the cold of the shower from the cylinder cold feed line, just before it enters the cylinder.

I've been looking at this again, and TBH the big problem is that I'd
just about have to rip the house apart to make all the changes you
suggest... eg must be about 17 metres from the stop cock to the HW tank;
that pipe is buried behind tiled boxing, under carpeted floors, goes up
and down levels, etc etc, all of which I'm sure contributes to the
pressure problem. I can't begin to imagine how much work it would take
to put it all right.

What it boils down to is, "is the problem severe enough to warrant all
that upheaval", and the answer has to be "no"!

If that sorts it then all is fine. If there is still problems replace the
mains pipe. Either way the internal pipes need sorting, so get them done
first.

One reason this issue has come now is that we're probably going to get
our drive done this summer, so now is the time to be digging it all up
to fit a new MDPE pipe out to the boundary. It certainly won't happen
after the new drive is laid.

So perversely, maybe it's the external pipework I'm looking at maybe
changing. Given the pressure readings in my last post, which seem to me
to indicate a 50:50 split between external and internal, would it still
be worthwhile changing only the outside pipework?

Check the isolation valves bewteen the pressure reduction valve and the
cylinder, sometimes these are not full bore, or are part turned off. Try
checking that that toilets and the cold side of the kitchen sink are not fed
from the pressure reduction valve. Check the strainer in the pressure
control valve is it furred up.

Lost me here... where would the pressure reduction valve be, and why
would I have one/need one, especially if I have a low pressure problem?

Thanks
David

"Lobster" wrote in message
...
James Salisbury wrote:
"Doctor Evil" wrote in message
...

Lobster wrote:

I posted a query here a few months ago asking whether it was likely
to
be worth my while biting the bullet and replacing the old incoming
water
main with a modern wide-bore MDPE affair

Before digging the ground up, I would get the pipes inside right first.

1. Install a full bore stop cock.
2. Have a dedicated 22mm pipe directly to the unvented cylinder.
3. Tee off at the stop cock and run to all cold supplies in the house
on a dedicated cold pipe.
4. Take the cold of the shower from the cylinder cold feed line, just
before it enters the cylinder.

I've been looking at this again, and TBH the big problem is that I'd
just about have to rip the house apart to make all the changes you
suggest... eg must be about 17 metres from the stop cock to the HW tank;
that pipe is buried behind tiled boxing, under carpeted floors, goes up
and down levels, etc etc, all of which I'm sure contributes to the
pressure problem. I can't begin to imagine how much work it would take
to put it all right.

What it boils down to is, "is the problem severe enough to warrant all
that upheaval", and the answer has to be "no"!

If that sorts it then all is fine. If there is still problems replace
the
mains pipe. Either way the internal pipes need sorting, so get them
done
first.

One reason this issue has come now is that we're probably going to get
our drive done this summer, so now is the time to be digging it all up
to fit a new MDPE pipe out to the boundary. It certainly won't happen
after the new drive is laid.

So perversely, maybe it's the external pipework I'm looking at maybe
changing. Given the pressure readings in my last post, which seem to me
to indicate a 50:50 split between external and internal, would it still
be worthwhile changing only the outside pipework?

Check the isolation valves bewteen the pressure reduction valve and the
cylinder, sometimes these are not full bore, or are part turned off. Try
checking that that toilets and the cold side of the kitchen sink are not
fed
from the pressure reduction valve. Check the strainer in the pressure
control valve is it furred up.

Lost me here... where would the pressure reduction valve be, and why
would I have one/need one, especially if I have a low pressure problem?

David, you said you had an unvented cylinder, so one will be there.

In your case as you are having the drive ripped up, get a new mains pipe run
in and see how that goes. If a long run then use 32mm. They may reduce it
and connect to 25mm at the street stop cock, but the resistance to
pressure/flow will be far less. And have a "full bore" stop cock in the
house.





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Doctor Evil wrote:
In your case as you are having the drive ripped up, get a new mains pipe run
in and see how that goes. If a long run then use 32mm. They may reduce it
and connect to 25mm at the street stop cock, but the resistance to
pressure/flow will be far less. And have a "full bore" stop cock in the
house.

I noticed you mentioned fitting a 'full bore' stop cock again elsewhere
today... by that do you just mean a stopcock with 22mm output as opposed
to 15mm, (like
http://www.screwfix.com/app/sfd/cat/...17273&ts=64119) or is the
'full bore' descriptor refering to something else?

Thanks
David