Question about water pressure in relation to valve and feeder pipe diameters...

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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:

<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
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Ken Moiarty wrote:

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.
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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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Ken Moiarty wrote:

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.
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Ken Moiarty wrote:

Hi, You just say pressure is on the low side. My house has regulator and gauge at the water main entry point. It's always more or less 60 psi. I can raise it higher if I want to.
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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.
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Take the shower head off and drill out the restricter orifice. You'll get plenty of volume and pressure from your 1/2" line.
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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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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.

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

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/consumer/default.php/cPath/421_277 http://www.h20managementservices.com/savershower.htm in Birkenhead Wirral
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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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[links to "water conservation" web sites deleted]
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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. .
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What answer was that?

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.

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?
wrote

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

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.
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See article at http://www.bobvila.com/HowTo_Library/Plumbing_Basics-Miscellaneous_Plumbing-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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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.

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
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Ken Moiarty wrote:

Hmmm, Ever thought about water conservation?
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