My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.
However, I also (long time ago) purchased an inline pressure balance valve
which my shower needs to prevent myself from getting either scalded or
cold-shocked everytime someone in my family turns a tap on or off elsewhere
in the house. But this inline pressure balance valve I have (and I had a
hard time finding an _inline_ one ...*) provides only 1/2 inch diameter
passages for the water to flow through it. With the water having to flow
through this smaller diameter before reaching my shower, I'm concerned about
whether or not this will hinder or undo the pressure increase resulting from
my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

{* Explanation regarding "inline" choice: I specifically wanted an _inline_
pressure balance valve as the commonly available ones, which are integrated
into a complete faucet-tap-fixture unit, would require me to have to mess
with my shower's ceramic tile in order to install.}

TIA,
Ken

PS: My apologies if I in error I might have crossposted this to the wrong
group.
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Ken Moiarty wrote:

My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.

SNIP

Sorry, IMHO you are on the wrong track.

1/2" Cu will easily support all the flow that
your shower can demand. In fact, 3/8" Cu would
probably not make any noticeable difference.

The flow problem you have is either caused by
inadequate pressure at the source or by restriction(s)
in the shower valving and head.

Do some more investigating before you expend a great
deal of effort and expense on the re-piping project.

Jim

Ken Moiarty wrote:

My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.
However, I also (long time ago) purchased an inline pressure balance valve
which my shower needs to prevent myself from getting either scalded or
cold-shocked everytime someone in my family turns a tap on or off elsewhere
in the house. But this inline pressure balance valve I have (and I had a
hard time finding an _inline_ one ...*) provides only 1/2 inch diameter
passages for the water to flow through it. With the water having to flow
through this smaller diameter before reaching my shower, I'm concerned about
whether or not this will hinder or undo the pressure increase resulting from
my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

{* Explanation regarding "inline" choice: I specifically wanted an _inline_
pressure balance valve as the commonly available ones, which are integrated
into a complete faucet-tap-fixture unit, would require me to have to mess
with my shower's ceramic tile in order to install.}

TIA,
Ken

PS: My apologies if I in error I might have crossposted this to the wrong
group.
Hi,
How many showers in your place? If more than one, do they all have
problem or only one you use? I am almost certain pipe size has nothing
to do with it. Problem is caused by some other factor. 1/2 inch pipe is
plenty for home use.

Ken,

Here's a few thoughts (I'm assuming both hot and cold are weak,
right?). First of all, have you checked the pressure with the shower
head removed? Maybe replacing the shower head will solve your pressure
problems. Often the head gets clogged with rust and sediment. If it's
not the shower head, then maybe the valve itself is clogged. Turn off
the water, and take the valve apart.

Running 3/4" pipe to the shower supplies won't help. The 1/2"
supplies are plenty big.

The one thing that caught my eye is that you have the problem of
getting scalded or cold-shocked when other fixtures are used. If the
plumbing is installed properly, it just shouldn't happen. Maybe the
problem is that your entire system is undersized, or maybe the water
supply coming into the house is undersized. In any case, you probably
need a pro to diagnose the situation.

Take the shower head off and drill out the restricter orifice. You'll
get plenty of volume and pressure from your 1/2" line.

"Ken Moiarty" wrote in message
...
My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.

Can you explain this? Are you changing the laws of physics and not telling
the rest of us? Oh, wait, I see you are in Canada; different laws.


I'm concerned about whether or not this will hinder or undo the pressure
increase resulting from my installation of the 3/4 inch pipes?

Not to worry, it won't hinder anything. See above.


Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

OK, you asked. First piece of advice is to find out the difference between
pressure and volume. Look at how a hydraulic cylinder works as a way to
help understand how pressure is actually made higher in the smaller diameter
lines.

Now determine exactly what your problem is. The pressure may be low, but it
may also be your perception do to lack of flow, or the dispersment of the
water from the shower head. Velocity is the key. I replaced a fairly
expensive shower head with one about 1/5 the price made by SaverShower. It
is the best shower heat I ever used even though it is a lower flow than
most. It is sufficient to rinse wll, but you have hte perception that you
are getting deluged with much more water than the actual flow.
Invest five bucks in this
http://www.energyfederation.org/cons.../cPath/421_277
http://www.h20managementservices.com/savershower.htm in Birkenhead Wirral

"Ken Moiarty" wrote in message
...
My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.
However, I also (long time ago) purchased an inline pressure balance valve
which my shower needs to prevent myself from getting either scalded or
cold-shocked everytime someone in my family turns a tap on or off
elsewhere in the house. But this inline pressure balance valve I have
(and I had a hard time finding an _inline_ one ...*) provides only 1/2
inch diameter passages for the water to flow through it. With the water
having to flow through this smaller diameter before reaching my shower,
I'm concerned about whether or not this will hinder or undo the pressure
increase resulting from my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

{* Explanation regarding "inline" choice: I specifically wanted an
_inline_ pressure balance valve as the commonly available ones, which are
integrated into a complete faucet-tap-fixture unit, would require me to
have to mess with my shower's ceramic tile in order to install.}

TIA,
Ken

PS: My apologies if I in error I might have crossposted this to the wrong
group.
--

I think you've received sufficient answers, but I wanted to reinforce what
others have stated. It isn't the pressure, its the shower head. I switched
my shower head to a low pressure model and right away I noticed a huge
difference in how the show "felt". It took some experimenting to be sure,
but I wouldn't trade my current one for nothing - and I've had it for years
now. Going to 3/4" is just going to make you hate life - especially
considering that you'll have to neck it down to 1/2" anyways at the shower
head - so all that 3/4" inch pipe won't make any difference anyway.

All three showers in the house have less pressure than what I prefer to
have. I have already seen to it that there are no "water savers" in any of
my showers. Open any faucet in my house and the water is on the
slow-flowing side. I believe this is due to (in addition to the 1/4 inch
pvc pipe used below sink faucets) the local water main pressure being
somewhat on the low side. Having the pressure regulator in my house cranked
to maximum, I have checked the water pressure at an outside faucet (when no
other taps/valves were open in or around the house) and found it to be in
the lower part of the typical range. (It's been a while since I did this,
so I don't recall the exact psi reading.)

Ken


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"Tony Hwang" wrote in message
news:OYAYg.148609$R63.129096@pd7urf1no...
Ken Moiarty wrote:

My shower lacks pressure so I want to replace the existing 1/2 inch
copper pipe that leads up to it with 3/4 inch copper pipe. Obviously, if
done correctly this will increase the water pressure available at my
shower. However, I also (long time ago) purchased an inline pressure
balance valve which my shower needs to prevent myself from getting either
scalded or cold-shocked everytime someone in my family turns a tap on or
off elsewhere in the house. But this inline pressure balance valve I
have (and I had a hard time finding an _inline_ one ...*) provides only
1/2 inch diameter passages for the water to flow through it. With the
water having to flow through this smaller diameter before reaching my
shower, I'm concerned about whether or not this will hinder or undo the
pressure increase resulting from my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

{* Explanation regarding "inline" choice: I specifically wanted an
_inline_ pressure balance valve as the commonly available ones, which are
integrated into a complete faucet-tap-fixture unit, would require me to
have to mess with my shower's ceramic tile in order to install.}

TIA,
Ken

PS: My apologies if I in error I might have crossposted this to the
wrong group.
Hi,
How many showers in your place? If more than one, do they all have problem
or only one you use? I am almost certain pipe size has nothing to do with
it. Problem is caused by some other factor. 1/2 inch pipe is
plenty for home use.

I've already seen to it that none of my showers have "water savers" or
restrictor orifices. (I'm very "politically incorrect" when it comes to
having these.)

Ken

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wrote in message
...
Take the shower head off and drill out the restricter orifice. You'll
get plenty of volume and pressure from your 1/2" line.

On Sun, 15 Oct 2006 17:25:14 -0700, "Ken Moiarty"
wrote:

My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.
However, I also (long time ago) purchased an inline pressure balance valve
which my shower needs to prevent myself from getting either scalded or
cold-shocked everytime someone in my family turns a tap on or off elsewhere
in the house. But this inline pressure balance valve I have (and I had a
hard time finding an _inline_ one ...*) provides only 1/2 inch diameter
passages for the water to flow through it. With the water having to flow
through this smaller diameter before reaching my shower, I'm concerned about
whether or not this will hinder or undo the pressure increase resulting from
my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

{* Explanation regarding "inline" choice: I specifically wanted an _inline_
pressure balance valve as the commonly available ones, which are integrated
into a complete faucet-tap-fixture unit, would require me to have to mess
with my shower's ceramic tile in order to install.}

TIA,
Ken

PS: My apologies if I in error I might have crossposted this to the wrong
group.

My $.02

Not to be argumentative with other posters, but 3/4 pipe has less
resistance to flow than 1/2, so for a given flow rate and pipe length
there *will* be less pressure drop, resulting in higher pressure
available at the shower head. But unless you have a very long run
it's won't be enough difference to make it worthwhile. BTW, this is
true even if your valve is 1/2, but the flow resistance of the valve
may very well cancel out the gain from upping the pipe size.

Others have made good suggestions, let me add another point: If your
showers are on higher floors, you loose a lot a pressure overcoming
gravity. This exacerbates the problem, especially if your pressure is
marginal to begin with.

A more practical solution than re-piping may be to add a booster pump.
If your main supply pressure is truly marginal, a booster pump will
work wonders. They are available as packaged solutions with a pump,
controls, and a very small pressure tank. Placed inline with your
cold water supply, it will help both cold and hot pressure throughout
your home.

HTH,

Paul

Thanks, but no thanks, for your personal advice. My apologies as well, as I
erred in my including the term, "advice", in conveying my request for
further information as would be germane to the content of my post.
Translation: I'm really asking only for discretely factual "information"
here, not personal attitudes and/or opinions.

Please and thank you,
Ken
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"Edwin Pawlowski" wrote in message
. net...

"Ken Moiarty" wrote in message
...
My shower lacks pressure so I want to replace the existing 1/2 inch
copper pipe that leads up to it with 3/4 inch copper pipe. Obviously, if
done correctly this will increase the water pressure available at my
shower.

Can you explain this? Are you changing the laws of physics and not
telling the rest of us? Oh, wait, I see you are in Canada; different
laws.


I'm concerned about whether or not this will hinder or undo the pressure
increase resulting from my installation of the 3/4 inch pipes?

Not to worry, it won't hinder anything. See above.


Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.

OK, you asked. First piece of advice is to find out the difference
between pressure and volume. Look at how a hydraulic cylinder works as a
way to help understand how pressure is actually made higher in the smaller
diameter lines.

Now determine exactly what your problem is. The pressure may be low, but
it may also be your perception do to lack of flow, or the dispersment of
the water from the shower head. Velocity is the key. I replaced a fairly
expensive shower head with one about 1/5 the price made by SaverShower. It
is the best shower heat I ever used even though it is a lower flow than
most. It is sufficient to rinse wll, but you have hte perception that you
are getting deluged with much more water than the actual flow.
Invest five bucks in this

[links to "water conservation" web sites deleted]

Ken Moiarty wrote:
All three showers in the house have less pressure than what I prefer to
have. I have already seen to it that there are no "water savers" in any of
my showers. Open any faucet in my house and the water is on the
slow-flowing side. I believe this is due to (in addition to the 1/4 inch
pvc pipe used below sink faucets) the local water main pressure being
somewhat on the low side. Having the pressure regulator in my house cranked
to maximum, I have checked the water pressure at an outside faucet (when no
other taps/valves were open in or around the house) and found it to be in
the lower part of the typical range. (It's been a while since I did this,
so I don't recall the exact psi reading.)

Ken

Ken
The presence of a pressure regulator is a useful clue. Those are not
usually installed on systems were the pressure from the water main is
low but rather were it is to high for ordinary plumbing to withstand.
It is sometimes true that a builder will go cheap on the regulator
itself and it will not be sized for an adequate flow.
--
Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.

"Ken Moiarty" wrote in message
...
Thanks, but no thanks, for your personal advice. My apologies as well, as
I erred in my including the term, "advice", in conveying my request for
further information as would be germane to the content of my post.
Translation: I'm really asking only for discretely factual "information"
here, not personal attitudes and/or opinions.

Please and thank you,
Ken

It is sufficient to rinse wll, but you have hte perception that you are
getting deluged with much more water than the actual flow.
Invest five bucks in this

[links to "water conservation" web sites deleted]

But you got the right answer didn't you? I noticed you deleted the links
that would be of value to you. but you can do your own search and find a
similar product that will solve your problem.

Glad I could be of help and fulfill your request for advice, even if it was
asked for in error. .

"Edwin Pawlowski" wrote

But you got the right answer didn't you?

What answer was that?

I noticed you deleted the links that would be of value to you. but you can
do your own search and find a similar product that will solve your
problem.


I'm not interested here in shower devices that do a better job of sprinkling
with less water. I'm only interested in getting information clarifying
whether my "mere 1/2 inch diameter" pressure-balance valve should prove or
prove not to be a bottleneck in my system; whether it will defeat or just
mildly offset the greater water volume that will be coming in from my freer
flowing 3/4 inch feeder pipes. My untrained intuition suggests it shouldn't
make too much difference. But having read some things too long ago to
recall with clarity now about pipe diameter determining relative water
pressure and volume, I was hoping to get some feedback from someone who
appears, either, to have had direct experience with such a scenario, or to
be authoritatively versed in hydraulic theory, so as to give me a more solid
idea of what to expect before going ahead with my plans.

Glad I could be of help and fulfill your request for advice, even if it
was asked for in error. .

I appreciate the well meaning attempt.

Ken


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Ken,

Don't mind Pollawsky's "wise ass" responses. He's been doing that for years
and we all just "deal with it".

There is some good information to be gained here but some "sifting" is
required. Makes life interesting, eh?

"Ken Moiarty" wrote in message
...

"Edwin Pawlowski" wrote

But you got the right answer didn't you?

What answer was that?

I noticed you deleted the links that would be of value to you. but you
can do your own search and find a similar product that will solve your
problem.


I'm not interested here in shower devices that do a better job of
sprinkling with less water. I'm only interested in getting information
clarifying whether my "mere 1/2 inch diameter" pressure-balance valve
should prove or prove not to be a bottleneck in my system; whether it will
defeat or just mildly offset the greater water volume that will be coming
in from my freer flowing 3/4 inch feeder pipes. My untrained intuition
suggests it shouldn't make too much difference. But having read some
things too long ago to recall with clarity now about pipe diameter
determining relative water pressure and volume, I was hoping to get some
feedback from someone who appears, either, to have had direct experience
with such a scenario, or to be authoritatively versed in hydraulic theory,
so as to give me a more solid idea of what to expect before going ahead
with my plans.

Glad I could be of help and fulfill your request for advice, even if it
was asked for in error. .

I appreciate the well meaning attempt.

Ken


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"Ken Moiarty" wrote in message
But you got the right answer didn't you?

What answer was that?

That the problem you are having is not pressure related. Volume and
velocity is what you need.




I'm not interested here in shower devices that do a better job of
sprinkling with less water. I'm only interested in getting information
clarifying whether my "mere 1/2 inch diameter" pressure-balance valve
should prove or prove not to be a bottleneck in my system; whether it will
defeat or just mildly offset the greater water volume that will be coming
in from my freer flowing 3/4 inch feeder pipes. My untrained intuition
suggests it shouldn't make too much difference.

You have been told by me and others that increasing the diameter is not
going to increase pressure. Those devices that do a better job of
sprinkling will do what you want with much less labor and expense than
increasing pipe sizes. Go beyond what you think is going to solve the
problem to something that will solve the problem. I have personal
experience with this.

"Craven Morehead" wrote in message
. ..
Ken,

Don't mind Pollawsky's "wise ass" responses. He's been doing that for
years and we all just "deal with it".

There is some good information to be gained here but some "sifting" is
required. Makes life interesting, eh?

No reason to "deal with it", just kill file me. OTOH, I do give some good
and accurate information. In this case, the OP asked for advice and I gave
it. Turns out, he did not want what he asked for. Hey, not my fault.

"Ken Moiarty" wrote in message
...
My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.
However, I also (long time ago) purchased an inline pressure balance valve
which my shower needs to prevent myself from getting either scalded or
cold-shocked everytime someone in my family turns a tap on or off
elsewhere
in the house. But this inline pressure balance valve I have (and I had a
hard time finding an _inline_ one ...*) provides only 1/2 inch diameter
passages for the water to flow through it. With the water having to flow
through this smaller diameter before reaching my shower, I'm concerned
about
whether or not this will hinder or undo the pressure increase resulting
from
my installation of the 3/4 inch pipes?

Any information, enlightenment, advice, or experience in regards to this
would be much appreciated.


Measure the pressure available - if it is low, that is your problem.
If not, raising the heater temp may help because then more cold
would be added to it to get the right temp - reducing pressure
losses in the hot pipe.

Did you have the problem before installing the balsance valve?

Bob

"Bob F" wrote

[...]
Did you have the problem before installing the balsance valve?

Bob


I haven't installed the balance valve yet.

Ken

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"Edwin Pawlowski" wrote in message
. com...

"Ken Moiarty" wrote in message
But you got the right answer didn't you?

What answer was that?

That the problem you are having is not pressure related. [...]


Oh, in that case... No, that was not the right answer.

snip

Ken

"Edwin Pawlowski" wrote in message
. com...

snip You have been told by me and others that increasing the diameter is
not going to increase pressure. snip


See article at
http://www.bobvila.com/HowTo_Library...ing-A1895.html

"The plumber and the plumbing designer rely on the internal diameter of the
water delivery pipes to control water pressure. The smaller the pipe
diameter, the lower the pressure and the greater the velocity of the water
moving through it."

"... manipulation of pressure is achieved entirely by varying the internal
diameters of the pipes."

Ken



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"Edwin Pawlowski" wrote in message
. com...


snip Volume and velocity is what you need.

Increased volume and velocity of the water _exiting of the shower head_
is what I want (what I "only need" is nobody's concern here). This is not
to be confused with velocity of flow in the supply pipe (i.e. the copper
pipe in the wall), which by itself has nothing to do with the velocity at
which water will exit the shower head. While the _velocity_ of the same or
similar quantity of water exiting the shower head may well be increased by a
low flow shower head (which I'm simply not interested in here for my own
reasons not related to anything being discussed here), there's no logical
reason to believe that volume (or quantity of water delivered per second)
will increase without an increase in supply pipe pressure.
And besides, if somehow a low flow shower head were to somehow result in
an increase in volume (quantity of water delivered per second) that would
only fly counter to the reason for the existence of "low flow" shower heads,
which is, to decrease (not increase) water consumption. So either you
are so bent on promoting water conservation devices that you'll say
anything, however confused, to get others to buy into the sales hype, or you
are someone who has succumbed to becoming confused by such hype yourself.

I have personal experience with this.

Then tell us your experience. I'd like to know the particulars about it, as
opposed to only what you've personally come to conclude 'in lieu of' it,
please.

TIA,
Ken

Ken,

I noticed everyone and his mother has been giving you advice. This
is coming from the plumbing newsgroup.

Increasing the feed pipes to 3/4" won't help. Incidentally, since
water is not compressible, the smallest pipe or port in the system
affects whatever's after it.

Here's three thoughts..

#1 Is the shower the only place in your house where this low
pressure occurs? If this problem exists elsewhere, write back for more
advice.

#2 Since the problem isn't a clogged shower head (which was the
first thing to check), then, assuming some rust hasn't lodged in the
valve body, I'd suspect the balancing valve itself. If you're handy
enough, take the valve out and see if that doesn't increase the
pressure. If it does, then just get a new valve. BTW, you shouldn't
need a balancing valve. Something is awry somewhere. Perhaps you'll
end up repiping the main arteries that feed the fixtures.

#3 Don't ask plumbing questions in the "alt.home.repair" group,
unless you want a bunch of amateurish, faulty advice.

First do what I've suggested, then write the plumbing group if you
need more advice. Sice we're not there to look at things ourselves, it
might take a message or two.

Mike Grooms wrote:
Ken,

I noticed everyone and his mother has been giving you advice. This
is coming from the plumbing newsgroup.

Thanks. Finally a response suggesting credibility.


Increasing the feed pipes to 3/4" won't help.

Okay, this appears on the surface to be saying exactly what others
before you have been saying. Am I to be sure then that you mean to be
saying here that using 3/4" pipe in place of the current 1/2" pipe
*won't* result in less pressure loss (in relation to the main supply
line into the house)? If so, maybe you could indulge my curiosity and
explain how this can be so in light of the many references that appear
to say otherwise (such as the "Bob Villa" reference I quoted, for
example)? But somehow I'm inclined to to think you don't mean to be
saying this at all, but rather could be somewhat misunderstanding my
original post.

Incidentally, since water is not compressible, the smallest pipe or port in the system
affects whatever's after it.


Thank you!. So a reduction in pipe diameter from, say 3/4" to 1/2" for
a travel distance of, say, 4" (the length of my PB valve) and then back
again, would definitely limit the pressure at the end to what it would
be if the entire line were just 1/2" in diameter to begin with?


Here's three thoughts..

#1 Is the shower the only place in your house where this low
pressure occurs? If this problem exists elsewhere, write back for more
advice.


No, the pressure is low throughout the house. (Bear in mind, however,
that when I say "low", I don't mean abnormally low; just lower than
what I've been used to from older dwellings I've lived in prior. I can
write back later and give you the actual psi value since my memory is
not so numerically precise, but I will tell you now that I recall
checking the water pressure at an outside faucet in the past and
finding it to be within the lower end of the normal range.)

#2 Since the problem isn't a clogged shower head (which was the
first thing to check), then, assuming some rust hasn't lodged in the
valve body, I'd suspect the balancing valve itself.

Okay, I don't have the valve installed yet. When I bought this house
there were no pressure balance valves installed whatsoever. Since the
time it was built however, local laws have come into effect that
require these be installed for each shower in all new (as well as legal
rental) dwellings. I have bought an inline pressure-balance valve
still waiting for me to install. But it's openings are only standard
1/2", as opposed to the 3/4" piping I have more recently been thinking
of installing for a separate and totally distinct reason (i.e. my
personal preference for increased overall pressure to shower - think
'President Lyndon Johnson with his 100 PSI shower in the White
House...', though not necessarily that extreme g)..., thus prompting
my original question.


If you're handy
enough, take the valve out and see if that doesn't increase the
pressure. If it does, then just get a new valve. BTW, you shouldn't
need a balancing valve. Something is awry somewhere. Perhaps you'll
end up repiping the main arteries that feed the fixtures.

This comes to me as a surprise. In every house I've ever lived in
prior to, as well as including, this one, people have had to time their
showers (or tell others before showering) in order to avoid being
scalded or cold-shocked while showering. I remember my Dad turning
down the thermostat of a new hot water tank that had just been
installed in his house, as a safety precaution to decrease the chance
of somebody getting seriously injured while showering in the event that
somebody opened or closed a tap somewhere unawares during.


#3 Don't ask plumbing questions in the "alt.home.repair" group,
unless you want a bunch of amateurish, faulty advice.

First do what I've suggested, then write the plumbing group if you
need more advice. Sice we're not there to look at things ourselves, it
might take a message or two.

Okay, thanks for your helpful feedback.

Ken

Paul Franklin wrote:

My $.02

Not to be argumentative with other posters, but 3/4 pipe has less
resistance to flow than 1/2, so for a given flow rate and pipe length
there *will* be less pressure drop, resulting in higher pressure
available at the shower head. But unless you have a very long run
it's won't be enough difference to make it worthwhile. BTW, this is
true even if your valve is 1/2, but the flow resistance of the valve
may very well cancel out the gain from upping the pipe size.


Yes, this is what I'm thinking could be the case. But I would like to
find out for more certain.

Others have made good suggestions, let me add another point: If your
showers are on higher floors, you loose a lot a pressure overcoming
gravity. This exacerbates the problem, especially if your pressure is
marginal to begin with.

This shower's on the lower floor.

A more practical solution than re-piping may be to add a booster pump.
If your main supply pressure is truly marginal, a booster pump will
work wonders. They are available as packaged solutions with a pump,
controls, and a very small pressure tank. Placed inline with your
cold water supply, it will help both cold and hot pressure throughout
your home.


Yes I've thought of this. But I'm not comfortable with the idea of
increasing the pressure for the entire household. If one of my
neighbors learned I was doing this during the summer months when water
restrictions are in effect (and inexplicably, water pressure for
everybody in the neighborhood always seems to be much lower than during
the rest of the year), I'm pretty sure I'd soon receive a visitor from
the city abruptly ordering me to 'shut er down' due to some
bureaucratic bylaw prohibiting such. (Hey, in this city where I now
live it's even illegal to use a sump pump, because -silly as it may
seem- that is considered to be abuse of public sewer system capacity.)

Ken

"My shower lacks pressure so I want to replace the existing 1/2 inch
copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done

correctly this will increase the water pressure available at my
shower."

The first paragraph of your post is incorrect and untrue. It makes me
wonder how you could be so judgemental of everyone's response when you
don't have a clue of what your asking yourself.

kenny b

wrote in message
oups.com...

"My shower lacks pressure so I want to replace the existing 1/2 inch
copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower."

The first paragraph of your post is incorrect and untrue. It makes me
wonder how you could be so judgemental of everyone's response when you
don't have a clue of what your asking yourself.
kenny b


Thank you. Your feelings are noted, kenny bs.

Ken

My apologies. I replied to your message last night from my work computer,
through Google Groups (since it doesn't have direct newsgroup access), and
forgot that my display name is slightly different there ("Ken" instead of
"Ken Moiarty"). So I'll paste and resubmit my reply to you below.
----

Mike Grooms wrote:
Ken,

I noticed everyone and his mother has been giving you advice. This
is coming from the plumbing newsgroup.

Thanks. Finally a response suggesting credibility.


Increasing the feed pipes to 3/4" won't help.

Okay, this appears on the surface to be saying exactly what others
before you have been saying. Am I to be sure then that you mean to be
saying here that using 3/4" pipe in place of the current 1/2" pipe
*won't* result in less pressure loss (in relation to the main supply
line into the house)? If so, maybe you could indulge my curiosity and
explain how this can be so in light of the many references that appear
to say otherwise (such as the "Bob Villa" reference I quoted, for
example)? But somehow I'm inclined to to think you don't mean to be
saying this at all, but rather could be somewhat misunderstanding my
original post.

Incidentally, since water is not compressible, the smallest pipe or port
in the system
affects whatever's after it.


Thank you!. So a reduction in pipe diameter from, say 3/4" to 1/2" for
a travel distance of, say, 4" (the length of my PB valve) and then back
again, would definitely limit the pressure at the end to what it would
be if the entire line were just 1/2" in diameter to begin with?


Here's three thoughts..

#1 Is the shower the only place in your house where this low
pressure occurs? If this problem exists elsewhere, write back for more
advice.


No, the pressure is low throughout the house. (Bear in mind, however,
that when I say "low", I don't mean abnormally low; just lower than
what I've been used to from older dwellings I've lived in prior. I can
write back later and give you the actual psi value since my memory is
not so numerically precise, but I will tell you now that I recall
checking the water pressure at an outside faucet in the past and
finding it to be within the lower end of the normal range.)

#2 Since the problem isn't a clogged shower head (which was the
first thing to check), then, assuming some rust hasn't lodged in the
valve body, I'd suspect the balancing valve itself.

Okay, I don't have the valve installed yet. When I bought this house
there were no pressure balance valves installed whatsoever. Since the
time it was built however, local laws have come into effect that
require these be installed for each shower in all new (as well as legal
rental) dwellings. I have bought an inline pressure-balance valve
still waiting for me to install. But it's openings are only standard
1/2", as opposed to the 3/4" piping I have more recently been thinking
of installing for a separate and totally distinct reason (i.e. my
personal preference for increased overall pressure to shower - think
'President Lyndon Johnson with his 100 PSI shower in the White
House...', though not necessarily that extreme g)..., thus prompting
my original question.


If you're handy
enough, take the valve out and see if that doesn't increase the
pressure. If it does, then just get a new valve. BTW, you shouldn't
need a balancing valve. Something is awry somewhere. Perhaps you'll
end up repiping the main arteries that feed the fixtures.

This comes to me as a surprise. In every house I've ever lived in
prior to, as well as including, this one, people have had to time their
showers (or tell others before showering) in order to avoid being
scalded or cold-shocked while showering. I remember my Dad turning
down the thermostat of a new hot water tank that had just been
installed in his house, as a safety precaution to decrease the chance
of somebody getting seriously injured while showering in the event that
somebody opened or closed a tap somewhere unawares during.


#3 Don't ask plumbing questions in the "alt.home.repair" group,
unless you want a bunch of amateurish, faulty advice.

First do what I've suggested, then write the plumbing group if you
need more advice. Sice we're not there to look at things ourselves, it
might take a message or two.

Okay, thanks for your helpful feedback.

Ken

--


----------------------------------------------------
This mailbox protected from junk email by MailFrontier Desktop
from MailFrontier, Inc. http://info.mailfrontier.com

kenny

The first paragraph of your post is incorrect and untrue. It makes me
wonder how you could be so judgemental of everyone's response when you
don't have a clue of what your asking yourself.

kenny b


Now Kenny, is that the way we plumbers write? You're going to give
everyone the impression that we're a little harsh.

Mike Grooms wrote:
kenny

The first paragraph of your post is incorrect and untrue. It makes me
wonder how you could be so judgemental of everyone's response when you
don't have a clue of what your asking yourself.

kenny b


Now Kenny, is that the way we plumbers write? You're going to give
everyone the impression that we're a little harsh.


Sorry I'm trying to stay away from the 4 letter words that come so easy
to us every day, it's the new me.

kenny b

"Ken" wrote in message
But it's openings are only standard
1/2", as opposed to the 3/4" piping I have more recently been thinking
of installing for a separate and totally distinct reason (i.e. my
personal preference for increased overall pressure to shower - think
'President Lyndon Johnson with his 100 PSI shower in the White
House...', though not necessarily that extreme g)..., thus prompting
my original question.

Pressure and volume are different things. Increasing the pipe size will NOT
increase the pressure. Can't happen. Won't happen. Put in a 6" pipe and
you won't get any more pressure If your feed from the street is corroded,
you may get better flow by replacing it, but putting in a section of larger
pipe will do nothing.

If you want to increase the pressure, the first step is to find what
pressure is at the street. Then you compare that to your house. If they
are the same, nothing you do will increase it. If you get a big pressure
drop, it may be from a flow restriction on the main to the house. What size
and type of pipe is it? If it is an old galvanzied pipe it may be corroded
or have buildup inside and giving restriction. This is a different scenario
than what you are suggesting. Replacing a section inside will do nothing.

If you want a high pressure shower, move to the town that I work in. We
have 110 psi feed.

Pressure and volume are different things. Increasing the pipe size will NOT
increase the pressure. Can't happen. Won't happen.

In the original post increasing the size won't do anything measurable,
"Can't happen. Won't happen" I don't think so.
In theory and in practice with long runs pressure drops will add up
and increasing the pipe diameter will increase the pressure at the
output end.

This thread keeps getting harder for me to believe! But a tentative picture
is beginning to form in my mind that there's some kind of "culture" gap at
play between myself and you guys here. If I was rude to anyone, I apologize
since I'm beginning to see I may have put a wrong construction on some of
the remarks made here. Edwin, you're not American are you? With that
smart-ass remark you initially made I had assumed you were (which goes to
perceived connotation, believe it or not). I see I really should have not
cross-posted to so many groups, otherwise I could have better anticipated
what part of the world someone was responding from (e.g. the U.K. in
free.uk.trade.plumbing, dah!). Yet it may not just be connotations that are
getting misinterpreted here. It must be technical things too. If it's not
that then it's either, you guys are all crazy, or (even less likely) I am
crazy; scenarios both of which seem to me at this time to be less than
highly probable.

"Edwin Pawlowski" wrote...
[...] Increasing the pipe size will NOT increase the pressure. Can't
happen. Won't happen. Put in a 6" pipe and you won't get any more
pressure

If you want to put it that way, nor will 'moving into a bigger house
increase my income'! I didn't quite mean it the way you have apparently
understood me to be speaking. I don't know exactly what psi my street's
water main is at. But I do know the pressure in it far exceeds that which
reaches my plumbing fixtures. By the same token, I also know that all the
1/2" copper pipes that feed these fixtures are connected to larger diameter
(3/4") intermediate pipes ("pipes" in plural as I'm referring to both the
hot and cold, respectively) which are at a higher psi, being that it is
*less decreased* removed from in the street than is the psi in the smaller
diameter 1/2" pipes.

Now I will stop here, and wait for feedback as to just this little bit,
before I continue to to finish trying to communicate myself to you on this
as least ambiguously as I can manage.


If your feed from the street is corroded, you may get better flow by
replacing it, but putting in a section of larger pipe will do nothing.

I never implied I was intending to "put in a section" of larger pipe. (The
statement in my original post, "if properly done", was meant to assure the
knowledgeable reader of my awareness here such as to preclude any such
unnecessary confusion.)


If you want to increase the pressure, the first step is to find what
pressure is at the street. Then you compare that to your house. If they
are the same, nothing you do will increase it.

Everyone around these parts expects that the pressure at the street is going
to be a lot higher than the pressure in the house is permitted to be. I've
never heard of both being the same. Certainly no place where I've lived (in
Canada, of course) have these been the same. What is it that makes one so
automatically presume that mine would be? Or that in presuming that these
are the same in my case, that I must therefore necessarily be to oblivious
to the obvious futility of any effort to get more pressure than is there to
tap into?


If you want a high pressure shower, move to the town that I work in. We
have 110 psi feed.


It's not going to be 110 psi at my shower since it has to go through
reductions in pipe diameter. Herein lies the rub: The less reduction in
pipe diameter after the main supply line, the greater (i.e. closer to the
original 110 psi) the pressure. Hence my rationale for replacing the 1/2"
diameter shower feeding runs (that currently branch from the central 3/4"
lines they are tied into), with 3/4" runs instead.

Ken

"Ken Moiarty" wrote in message
...
This thread keeps getting harder for me to believe! But a tentative
picture is beginning to form in my mind that there's some kind of
"culture" gap at play between myself and you guys here. If I was rude to
anyone, I apologize since I'm beginning to see I may have put a wrong
construction on some of the remarks made here. Edwin, you're not American
are you? With that smart-ass remark you initially made I had assumed you
were (which goes to perceived connotation, believe it or not). I see I
really should have not cross-posted to so many groups, otherwise I could
have better anticipated what part of the world someone was responding from
(e.g. the U.K. in free.uk.trade.plumbing, dah!). Yet it may not just be
connotations that are getting misinterpreted here. It must be technical
things too. If it's not that then it's either, you guys are all crazy, or
(even less likely) I am crazy; scenarios both of which seem to me at this
time to be less than highly probable.

"Edwin Pawlowski" wrote...
[...] Increasing the pipe size will NOT increase the pressure. Can't
happen. Won't happen. Put in a 6" pipe and you won't get any more
pressure

If you want to put it that way, nor will 'moving into a bigger house
increase my income'! I didn't quite mean it the way you have apparently
understood me to be speaking. I don't know exactly what psi my street's
water main is at. But I do know the pressure in it far exceeds that which
reaches my plumbing fixtures. By the same token, I also know that all the
1/2" copper pipes that feed these fixtures are connected to larger
diameter (3/4") intermediate pipes ("pipes" in plural as I'm referring to
both the hot and cold, respectively) which are at a higher psi, being that
it is *less decreased* removed from in the street than is the psi in the
smaller diameter 1/2" pipes.

Now I will stop here, and wait for feedback as to just this little bit,
before I continue to to finish trying to communicate myself to you on this
as least ambiguously as I can manage.


If your feed from the street is corroded, you may get better flow by
replacing it, but putting in a section of larger pipe will do nothing.

I never implied I was intending to "put in a section" of larger pipe.
(The statement in my original post, "if properly done", was meant to
assure the knowledgeable reader of my awareness here such as to preclude
any such unnecessary confusion.)


If you want to increase the pressure, the first step is to find what
pressure is at the street. Then you compare that to your house. If they
are the same, nothing you do will increase it.

Everyone around these parts expects that the pressure at the street is
going to be a lot higher than the pressure in the house is permitted to
be. I've never heard of both being the same. Certainly no place where
I've lived (in Canada, of course) have these been the same. What is it
that makes one so automatically presume that mine would be? Or that in
presuming that these are the same in my case, that I must therefore
necessarily be to oblivious to the obvious futility of any effort to get
more pressure than is there to tap into?


If you want a high pressure shower, move to the town that I work in. We
have 110 psi feed.


It's not going to be 110 psi at my shower since it has to go through
reductions in pipe diameter. Herein lies the rub: The less reduction in
pipe diameter after the main supply line, the greater (i.e. closer to the
original 110 psi) the pressure. Hence my rationale for replacing the 1/2"
diameter shower feeding runs (that currently branch from the central 3/4"
lines they are tied into), with 3/4" runs instead.

Ken



You've cross posted to many groups - This reply is from
pdaxs.services.plumbing.

I am not sure whether you are wanting a debate or an answer to a question.
Either that or you are hell bent to change your supply to 3/4". If the
latter is your intent then why come ask anything, just do what you want. You
certainly don't need our permission.
If it's the former then I am going to give you your answer, but I've been
plumbing way too long to debate anyone about anything.

There are two different characteristics that affect the perceived amount of
water flow from a faucet.
1. Pressure
2. Volume

Plumbers don't use those terms interchangeably. Upsizing your lines will not
increase your pressure. It will increase your volume.....BUT.....
ONLY if you change the valve to something that was designed to accept the
larger supply lines. The industry standard (in the states) is 1/2". It works
just fine on every valve I've installed for thirty years. I thought I read
in one of the previous posts where someone brought up your valve. That's the
key.
If you've tried changing showerheads and/or removing water savers then I'd
recommend that you go out and buy yourself a brand new Moen pressure
balancing valve and install it.

I thought someone else suggested adjusting your PRV (pressure reducing
valve)
I have no idea if you have one or not, but if you don't have a history of
problems and now you do, I'd look real hard at that valve if you have one.
The "moving parts" of any system are always the weak link.
Pipe is not a "moving part".
If this problem just popped up, look at the "moving parts" first.

Bob Wheatley

There's a lot of misinformation and incomplete information in this
thread. Let's bring some citations and facts to the game. You wanted
details and facts, here you go.

At least part of the mess here is due to confusing static pressure and
dynamic pressure. In this context, static pressure is the pressure at
a specified point in the system when flow is zero. Dynamic pressure
is pressure at a specified point in the system when water is flowing
at some non-zero rate.

What you asked about is the dynamic pressure at the showerhead when
the water is flowing at whatever rate it flows when you have the
shower on. The greater the dynamic pressure at that point, the more
forceful the shower stream will seem, for a given showerhead. Yes, as
many posters have pointed out, different showerheads will feel better
or worse all else being the same, but for a given showerhead, the
higher the dynamic pressure at the showerhead, the more forceful feel
the water streams will have.

So first a word about static pressure. The static pressure at the
shower head is determined by the static pressure at the point your
water pipe enters your house, minus 0.433 lbs for every foot of
elevation difference between the entry point and the shower head,
assuming your showerhead is higher than the entry point and you don't
have a pressure regulator valve. So if the static pressure at the
entry point is 50 lbs, and your showerhead is 10 feet higher than the
entry point, the static pressure at the showerhead will be 45.67 lbs.

Note that pipe size (within reason), number of turns, fittings, etc.,
does not enter into this. So when a previous poster says pipe size
doesn't affect pressure, they are talking about static pressure (or
they are wrong, see below).

For a good explanation of static pressure, see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

On to dynamic pressure. When water flows through a pipe, a pressure
drop occurs along the pipe due to the energy that is required to
overcome the friction between the pipe and the flowing water. Pressure
drop in a pipe is affected by flow rate, the viscosity of the liquid,
the diameter of the pipe, and how smooth the pipe interior is
(corrosion and deposits increase pressure drop).

Fittings such as els, tees, shutoffs, etc., also cause a pressure
drop, and for the same reason. Pressure drop for fittings is often
expressed as the length of equal diameter pipe that would cause the
same pressure drop at the same flow rate.

For an example, a 1/2 inch copper el has a pressure drop equivilent to
2 inches of 1/2 copper pipe. A 3/4 copper el has a pressure drop
equivilent to 3 inches of 3/4 copper pipe.

Pressure drop is usually expressed as lbs per 100 feet of pipe at a
given flow rate. For an example, water flowing at 2 gpm through 1/2
copper pipe will have a pressure drop of 2.6 lbs per hundred feet. For
3/4 copper pipe under the same 2.0 gpm flow, the pressure drop is 0.5
lbs per hundred feet.

For a good explanation of pressure drop and tables for pipe and
fittings see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

What does all this mean for your shower?

Let assume the pressure at the entry point to your house is 50lbs.
Lets assume you have 4 elbows and 100 feet of total pipe length (not
counting the elbows) between the entry and your showerhead, and that
the showerhead is 10 feet higher than the entry point. Let's also
assume copper pipe and a flow rate of 2 gpm. What will be the dynamic
pressure at the showerhead with both 1/2 inch and 3/4 inch pipe?

Dynamic pressure at showerhead equals static pressure at entry, minus
static pressure drop due to change in elevation, minus dynamic
pressure drop in pipe, minus dynamic pressure drop in fittings.

For 1/2 inch this is:

50 - (.433 x 10) - 2.6 - (((4 x 2) / 1200) x 2.6) = 43.0527lbs

For 3/4 inch this is:

50 - (.433 x 10) - 0.5 - (((4 x 3) / 1200) x 0.5) = 45.165

All the figures come from the cited references.

The complicated term is the number of ells times the equivilent length
of pipe in inches divided by the number of inches in 100 feet, times
the pressure drop of pipe per 100 feet.

So for the above example, the dynamic pressure will be a little over
two lbs greater for 3/4 pipe compared to 1/2 pipe. Will you notice it
standing in the shower? I doubt it.

You will notice that the pressure drop due to elevation change is the
major factor, followed by the dynamic drop of the 100 feet of pipe.
The elbows contribute only a tiny amount.

Sticking a valve in the pipe will add a dynamic pressure drop term to
the calculation. The magnitude of the term will depend on the valve
and the flow rate but it will be the same for the two cases, so you
will still be better off (albeit only a tiny bit) with 3/4 pipe.

For completeness I will mention one complicating factor. The above
calculations assume the same flow rate in both cases. However, in
practice this won't quite be true, because the dynamic pressure is
higher in the 3/4 case. This will mean the flow rate will be slightly
higher, which will increase all the pressure drops slightly. The net
affect is that the difference in practice will be even less than shown
above.

I hope this helps clear up some of the confusion.

Paul Franklin

Ken Moiarty wrote:
My shower lacks pressure so I want to replace the existing 1/2 inch copper
pipe that leads up to it with 3/4 inch copper pipe. Obviously, if done
correctly this will increase the water pressure available at my shower.

Increasing diameter increases flow, not pressure. Pressure is
determined by head, or height of fixture relative to height of water
source if no pumps are used. Increase pressure by having your
town buy a new water tower.

Increasing to 3/4" would be useful for multiple showerhead fixtures.

"Ken Moiarty" wrote in message
If you're handy
enough, take the valve out and see if that doesn't increase the
pressure. If it does, then just get a new valve. BTW, you shouldn't
need a balancing valve. Something is awry somewhere. Perhaps you'll
end up repiping the main arteries that feed the fixtures.

This comes to me as a surprise. In every house I've ever lived in
prior to, as well as including, this one, people have had to time their
showers (or tell others before showering) in order to avoid being
scalded or cold-shocked while showering. I remember my Dad turning
down the thermostat of a new hot water tank that had just been
installed in his house, as a safety precaution to decrease the chance
of somebody getting seriously injured while showering in the event that
somebody opened or closed a tap somewhere unawares during.

I've never lived in a house with such a problem, and I've seen some
pretty corroded galvanized pipes. It would take a significant constriction
in the cold line to make this a problem if you have reasonable supply
pressure.

You really need to be looking at your static water pressure and make sure
all valves in the supply are open fully.

Bob

"Paul Franklin" wrote in message
...
There's a lot of misinformation and incomplete information in this
thread. Let's bring some citations and facts to the game. You wanted
details and facts, here you go.

At least part of the mess here is due to confusing static pressure and
dynamic pressure. In this context, static pressure is the pressure at
a specified point in the system when flow is zero. Dynamic pressure
is pressure at a specified point in the system when water is flowing
at some non-zero rate.

What you asked about is the dynamic pressure at the showerhead when
the water is flowing at whatever rate it flows when you have the
shower on. The greater the dynamic pressure at that point, the more
forceful the shower stream will seem, for a given showerhead. Yes, as
many posters have pointed out, different showerheads will feel better
or worse all else being the same, but for a given showerhead, the
higher the dynamic pressure at the showerhead, the more forceful feel
the water streams will have.

So first a word about static pressure. The static pressure at the
shower head is determined by the static pressure at the point your
water pipe enters your house, minus 0.433 lbs for every foot of
elevation difference between the entry point and the shower head,
assuming your showerhead is higher than the entry point and you don't
have a pressure regulator valve. So if the static pressure at the
entry point is 50 lbs, and your showerhead is 10 feet higher than the
entry point, the static pressure at the showerhead will be 45.67 lbs.

Note that pipe size (within reason), number of turns, fittings, etc.,
does not enter into this. So when a previous poster says pipe size
doesn't affect pressure, they are talking about static pressure (or
they are wrong, see below).

For a good explanation of static pressure, see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

On to dynamic pressure. When water flows through a pipe, a pressure
drop occurs along the pipe due to the energy that is required to
overcome the friction between the pipe and the flowing water. Pressure
drop in a pipe is affected by flow rate, the viscosity of the liquid,
the diameter of the pipe, and how smooth the pipe interior is
(corrosion and deposits increase pressure drop).

Fittings such as els, tees, shutoffs, etc., also cause a pressure
drop, and for the same reason. Pressure drop for fittings is often
expressed as the length of equal diameter pipe that would cause the
same pressure drop at the same flow rate.

For an example, a 1/2 inch copper el has a pressure drop equivilent to
2 inches of 1/2 copper pipe. A 3/4 copper el has a pressure drop
equivilent to 3 inches of 3/4 copper pipe.

Pressure drop is usually expressed as lbs per 100 feet of pipe at a
given flow rate. For an example, water flowing at 2 gpm through 1/2
copper pipe will have a pressure drop of 2.6 lbs per hundred feet. For
3/4 copper pipe under the same 2.0 gpm flow, the pressure drop is 0.5
lbs per hundred feet.

For a good explanation of pressure drop and tables for pipe and
fittings see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

What does all this mean for your shower?

Let assume the pressure at the entry point to your house is 50lbs.
Lets assume you have 4 elbows and 100 feet of total pipe length (not
counting the elbows) between the entry and your showerhead, and that
the showerhead is 10 feet higher than the entry point. Let's also
assume copper pipe and a flow rate of 2 gpm. What will be the dynamic
pressure at the showerhead with both 1/2 inch and 3/4 inch pipe?

Dynamic pressure at showerhead equals static pressure at entry, minus
static pressure drop due to change in elevation, minus dynamic
pressure drop in pipe, minus dynamic pressure drop in fittings.

For 1/2 inch this is:

50 - (.433 x 10) - 2.6 - (((4 x 2) / 1200) x 2.6) = 43.0527lbs

For 3/4 inch this is:

50 - (.433 x 10) - 0.5 - (((4 x 3) / 1200) x 0.5) = 45.165

All the figures come from the cited references.

The complicated term is the number of ells times the equivilent length
of pipe in inches divided by the number of inches in 100 feet, times
the pressure drop of pipe per 100 feet.

So for the above example, the dynamic pressure will be a little over
two lbs greater for 3/4 pipe compared to 1/2 pipe. Will you notice it
standing in the shower? I doubt it.

You will notice that the pressure drop due to elevation change is the
major factor, followed by the dynamic drop of the 100 feet of pipe.
The elbows contribute only a tiny amount.

Sticking a valve in the pipe will add a dynamic pressure drop term to
the calculation. The magnitude of the term will depend on the valve
and the flow rate but it will be the same for the two cases, so you
will still be better off (albeit only a tiny bit) with 3/4 pipe.

For completeness I will mention one complicating factor. The above
calculations assume the same flow rate in both cases. However, in
practice this won't quite be true, because the dynamic pressure is
higher in the 3/4 case. This will mean the flow rate will be slightly
higher, which will increase all the pressure drops slightly. The net
affect is that the difference in practice will be even less than shown
above.

I hope this helps clear up some of the confusion.

Paul Franklin

This is a real good and complete explanation of the situation. I had noticed
that some posters were referring to static pressure and others to dynamic
pressure without stating which.

I agree with the conclusion that increasing the pipe size is very unlikely
to satisfactorily solve the problem. The 1/2 inch pipe is adequate for the
service and is pretty much standard in the plumbing systems I have come in
contact with. I suspect low source pressure, a faulty reducing valve, a
localized restriction such as a clogged screen, obstruction in the pipe, or
obstruction in the valve. It is also possible that the pathway has
generalized obstruction caused by deposits in the piping. If there is
another restriction, then increasing the pipe size will theoretically and
actually increase the water flow, but it is unlikely to be any significant
amount of increase.

Don Young

wrote in message
...

In the original post increasing the size won't do anything measurable,
"Can't happen. Won't happen" I don't think so.
In theory and in practice with long runs pressure drops will add up
and increasing the pipe diameter will increase the pressure at the
output end.

Increasing pipe diameter reduces restriction on the flow. Static pressure
remains exactly the same. There will be less pressure drop once the flow is
started. But pressure is never increased by larger pipes.

Paul Franklin wrote:
There's a lot of misinformation and incomplete information in this
thread.

You've hit the nail right on the head! A lot of "incomplete
information" and/or incomplete communication (which I'll admit to being
a part of, as well).

Let's bring some citations and facts to the game. You wanted
details and facts, here you go.

At least part of the mess here is due to confusing static pressure and
dynamic pressure. In this context, static pressure is the pressure at
a specified point in the system when flow is zero. Dynamic pressure
is pressure at a specified point in the system when water is flowing
at some non-zero rate.

What you asked about is the dynamic pressure at the showerhead when
the water is flowing at whatever rate it flows when you have the
shower on. The greater the dynamic pressure at that point, the more
forceful the shower stream will seem, for a given showerhead. Yes, as
many posters have pointed out, different showerheads will feel better
or worse all else being the same, but for a given showerhead, the
higher the dynamic pressure at the showerhead, the more forceful feel
the water streams will have.

So first a word about static pressure. The static pressure at the
shower head is determined by the static pressure at the point your
water pipe enters your house, minus 0.433 lbs for every foot of
elevation difference between the entry point and the shower head,
assuming your showerhead is higher than the entry point and you don't
have a pressure regulator valve. So if the static pressure at the
entry point is 50 lbs, and your showerhead is 10 feet higher than the
entry point, the static pressure at the showerhead will be 45.67 lbs.

Note that pipe size (within reason), number of turns, fittings, etc.,
does not enter into this. So when a previous poster says pipe size
doesn't affect pressure, they are talking about static pressure (or
they are wrong, see below).

For a good explanation of static pressure, see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

On to dynamic pressure. When water flows through a pipe, a pressure
drop occurs along the pipe due to the energy that is required to
overcome the friction between the pipe and the flowing water. Pressure
drop in a pipe is affected by flow rate, the viscosity of the liquid,
the diameter of the pipe, and how smooth the pipe interior is
(corrosion and deposits increase pressure drop).

Fittings such as els, tees, shutoffs, etc., also cause a pressure
drop, and for the same reason. Pressure drop for fittings is often
expressed as the length of equal diameter pipe that would cause the
same pressure drop at the same flow rate.

For an example, a 1/2 inch copper el has a pressure drop equivilent to
2 inches of 1/2 copper pipe. A 3/4 copper el has a pressure drop
equivilent to 3 inches of 3/4 copper pipe.

Pressure drop is usually expressed as lbs per 100 feet of pipe at a
given flow rate. For an example, water flowing at 2 gpm through 1/2
copper pipe will have a pressure drop of 2.6 lbs per hundred feet. For
3/4 copper pipe under the same 2.0 gpm flow, the pressure drop is 0.5
lbs per hundred feet.

For a good explanation of pressure drop and tables for pipe and
fittings see:

http://www.nationaldriller.com/CDA/A...00f932a8c0____

What does all this mean for your shower?

Let assume the pressure at the entry point to your house is 50lbs.
Lets assume you have 4 elbows and 100 feet of total pipe length (not
counting the elbows) between the entry and your showerhead, and that
the showerhead is 10 feet higher than the entry point. Let's also
assume copper pipe and a flow rate of 2 gpm. What will be the dynamic
pressure at the showerhead with both 1/2 inch and 3/4 inch pipe?

Dynamic pressure at showerhead equals static pressure at entry, minus
static pressure drop due to change in elevation, minus dynamic
pressure drop in pipe, minus dynamic pressure drop in fittings.

For 1/2 inch this is:

50 - (.433 x 10) - 2.6 - (((4 x 2) / 1200) x 2.6) = 43.0527lbs

For 3/4 inch this is:

50 - (.433 x 10) - 0.5 - (((4 x 3) / 1200) x 0.5) = 45.165

That slight of a pressure difference, eh? Now it's all beginning to
make sense to me.


All the figures come from the cited references.

The complicated term is the number of ells times the equivilent length
of pipe in inches divided by the number of inches in 100 feet, times
the pressure drop of pipe per 100 feet.

So for the above example, the dynamic pressure will be a little over
two lbs greater for 3/4 pipe compared to 1/2 pipe. Will you notice it
standing in the shower? I doubt it.


Yes, yes. I see it now.


You will notice that the pressure drop due to elevation change is the
major factor, followed by the dynamic drop of the 100 feet of pipe.
The elbows contribute only a tiny amount.

Sticking a valve in the pipe will add a dynamic pressure drop term to
the calculation.
The magnitude of the term will depend on the valve
and the flow rate but it will be the same for the two cases, so you
will still be better off (albeit only a tiny bit) with 3/4 pipe.

For completeness I will mention one complicating factor. The above
calculations assume the same flow rate in both cases. However, in
practice this won't quite be true, because the dynamic pressure is
higher in the 3/4 case. This will mean the flow rate will be slightly
higher, which will increase all the pressure drops slightly. The net
affect is that the difference in practice will be even less than shown
above.

I hope this helps clear up some of the confusion.



This has most certainly done so for me. My questions are now finally
satisified. I thank you very much, Paul.

Ken