3/4 supply.....1/2 section.....3/4 run....
Just a quickie. I thought I saw this answer before somewhere, but now I can't seem to find it again.
My question is one of fluid dynamics:
I have a 1/2" (copper) supply coming into my bathroom that changed from 3/4", inside the wall about 4". Impossible to reach without destroying adjacent bath. It was feeding just a shower in this room, but now I want to feed a shower and bath so I need it to be 3/4" for another 15 ft or so....
Can a 3/4 supply line have about a 1 foot section of 1/2" pipe in it without any noticeable drop in pressure or volume?:confused:
Plumber buddy says "No sweat".;) Just put reducer coupling at accessible point and go back to 3/4" for remaining run....."Absolutely NO drop in performance":D
Of course I'm here for a second, third, and fourth opinion because this will be feeding a multiple head shower and I'd hate to regret it later.....:(
Thanks a lot for your time!
do you have a choice anyway???
If what you said is true, you
would have to tear up another bathroom
just to even get to 3/4 pipe.......
just do it and see what happens...
then worry about gutting the other bathroom.
as far as flow charts and graphs goes ......
Las Vegas odds are probably 85% good in your favor...
so what more can you ask...
my 9 year old is now thorwing up and sitting on toilet....
a wonderful day had by all
you wont notice any noise levels
I really like those charts about the copper
I cant figure them out, but they are very impressive.....
you are not going hear a difference ,
no way , no how.....
especially while you are showering....
reducing noise. Measuring flow.
good to know! Three.
So, you want a lot of water, and as little pipe noise as possible. Very normal. I've never met a person who wanted the opposite. :)
Friction losses are a linear sum of the distance. A short distance of narrower pipe is not a long distance. Everyone keeps posting the same info, worded differently. Your plumber friend is right, within reason. To go deeper, just FYI, it is irrelevant where the narrow piece is in the entire run; it is independent.
So, a short distance doesn't add a lot of resistance to your flow.
It is true that it is more like a nozzle -- and no-one can predict the noises it will produce when "stressed" to its maximum limit, even if one could be there and see all the shapes (bends in of the pipe). Any direct contact to studs or other structure will transmit noise through solid material and then into the air where you can then hear it. So, it you can slide a thin pad between the pipe and its strapping, that will help a lot.
Musical instruments are complex geometry. Even the temperature of your hot water will change the noise the pipe produces. Personally, I think that the shape of the 3/4" pipe right after the 1/2" segment is what will determine a good part of the possible noise. Are you aware of how water produces microscopic vapor bubbles when it is pressurized and flowing fast over a microscopically rough surface like the inside of a copper pipe? This produces a hiss noise or lisping whistle. This noise gets amplified (slightly) at the 3/4" aperture acting like a horn spout does. When these bubbles come out of the 1/2" pipe, they won't get absorbed back into the main stream of water right away, but will at first expand a bit since the pressure has dropped. These two sudden changes will make some form of music or noise too, which then travels inside the water to an elbow or bend and then comes out into the air there. The length of the straight pipe determines at least one of the harmonics in the noise. That's the hypothesis, which you can verify by building a batch of similar setups and measuring noise as you change one variable at a time. If you were so inclined.
If anyone has more to add about pipe noises, please feel free to contradict me; I am eager and willing to learn what ever you know.
Now, Mr. Baum, if you really want to know whether you can fan out to three nozzles running 2.5 GpM each, and have acceptable plumbing performance elsewhere too, here is a way to test before installing. Build a pipe run equivalent (in number of elbows, and in total length, and in 3/4" copper) to the one you intend to install in your walls, and run it into the tub. Time how long it takes to fill the tub to e.g. 60 gallons, while turning on all the water (tub and shower, flushing toilet too). Note if you do not install the shower nozzles in this simulation as you are looking to know the total maximum amount of water you can get, you will not have the ultimate end flow, since a shower nozzle is a restriction, a friction, which reduces flow too. But I wouldn't sweat it. You can repeat this filling experiment with and without all the other variables.
1. More length = more loss = less water.
2. More bends = more loss = less water.
3. Shape of bends is one factor in creating noise.
4. Padding to prevent direct physical contact is important.
Since noises can start to happen later, it is good to pad even if there is no noise.
hope this helps.