I LIVE IN OHIO, AND I ALWAYS PLUMB HOUSES WITH TYPE M COPPER WHICH IS NORMAL IN MY AREA
I HAVE A CUSTOMER WITH A LOG HOUSE THAT A PLUMBER ALREADY DID THE UNDERSLAB BASEMENT PLUMBING AND THEN BACKED OUT. HE CONVINCED THEM TO USE WHAT THEY CALLED RED AND BLUE PLASTIC WATER PIPE, AFTER SEARCHING THE WEB I CAME UP WITH IPEX.
CAN SOMEONE TELL ME ABOUT IT, IF I WOULD PLUMB IT THE STANDARD WAY OR WOULD I USE THE HOMERUN METHOD AND I'VE READ PAST POST ABOUT NEEDING LARGER PIPE BECAUSE OF I.D. OF THE PIPE. IS THAT TRUE?

All that re-sizing stuff can add up. If you have the option of maintaining 3/4" mains to the last 2 branches it will pay off with better pressure. If not, I would not loose too much sleep over it. In the normal home, the differance will not be noticed.

Also, It is my opinion that PEX is superior in every way to M copper. I normally stress type "A" PEX, but A or B is better, stronger and will out last M copper.

As far as home run or traditional method, that is personal preferance as much as anything.

Look at a piece of 1/2" and you will see that the opening is not much larger than a piece of 3/8" copper tubing.

A 1/2" fitting yes, the pipe not much smaller at all. The pressure loss through the fittings is substantial but you can keep joints down with PEX, or use full port fittings like Everlock. There are some really easy to use 90* support bend pieces out there with nailer brackets on them that make a 90* bend in about 3" using the pipe without joints. It snaps in in a second too. A lot faster then a crimp 90* and 0 chance of a leak!

Also, if you have ever seen a flow venturi in an 8" hot water heating main that has a 2" hole in it, you know that the actual flow drop though a small opening in a short distance is not all that great.

I'm not smart enough to understand it fully, much less explain it, but I always wondered why not just run 2" pipe instead of 8" when you have a venturi like that in the line? (That's why I'm a plumber and not an engineer.)

Anyway, the same thing is true in any piping system. There are pressure and flow drops on any fitting, but by themselves are minimal. If joints are kept to a minimum, there should be no problem.

I would keep to 3/4" though on the runs to the last 2 branches, then use a 3/4" x 1/2" x 1/2" tee to get the last two.

Excuse me, but if two pipes have the same outer diameter and one has a thin wall and the other a thick wall the second one will have a smaller hole through it. And since the reduction takes place around the outer diameter, the difference in capacity is dramatically different. Once you introduce a fitting into the smaller pipe, it does reduce the size further, but since the reduction is for a short distance, the flow resistance is negligible so the capacity is not seriously affected.

Don't you guys calculate pressure losses in plumbing new construction water lines?

Pex is very slick and in homerun applications has no other pressure losses than its friction loss due to having no fittings other than the one on each end of the run. Compared to copper with numerous fittings the lessor ID is not a problem and in many cases using same size comparisons, PEX will deliver the sam gpm or more than the same size copper.

Also, doesn't most fixture feed lines reduce to 3/8"? And if they don't.... aren't all fixtures water conservation types anyway with limited gpm ratings?

I'm not a plumber and I know the answers are Yes and Yes. So why use plumbing that can provide much more water than the building's required flow needs? Or more to the point, than the fixture needs or can use?

To me there is no reason to do so. And thereby my thinking is it's done to support not changing from copper to something else rather than the arguement being logic based.

As to the venturi. The velocity of the fluid increases going through the venturi, so there is very little pressure loss and most venturies are very smooth, unlike the right angle the water flow sees going through an ID reduction type fitting.

Gary
Quality Water Asscoiates

IT SOUNDS LIKE IF I USE THE PEX I SHOULD USE THE HOME RUN METHOD. IN MY AREA MOST PLUMBERS REFER TO PEX AS JUNK. I WOULD PROBABLY NOT USE IT IF THE CUSTOMER HAD NOT REQUESTED IT. HOW MANY DIFFERENT TYPES OF PEX ARE THERE AND ARE MOST COLOR CODED FOR HOT AND COLD?

Something is to be said about piping and it's uses because there is so much controversy about this product and what to consider in it's application.
I admit, I have alot to learn about this product and it's uses, and plastic piping is used in many ways in different applications.


It happens in these forums and out in the field alike. The only issue that presses me is the long-term effects and what happens years long after I have left, short of the main issue being, What customers think when you go trying to change thier piping. It then makes it subject to criticism in an area where copper dominates the industry standard. People could easily refuse this product from being installed if they don't know what history shows in it's functionality. And yes, I agree, It can provide good functionality in some cases of applications.


Now, I have never recalled in any situation discussing copper piping in this way.



A little food for thought when anyone reads this posting.


Granted, I do see some advantages to this piping in certain circumstances....but I have scratched all the hair off my head and now I'm bald thinking about it.



Anyone know a good rogaine site?



Post Edited

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Everything in Plumbing can be repaired or replaced.

Homerun it or go to 3/4" if not. But the rest of your comments causes me to ask you what your opinion is based on other than hearsay gossip? And if you think it's a good idea for you to go on what the uninformed say.

PEX has a 25+ year problem free history in Europe and so far about 10 years here in the US. PB also (still) has a long problem free history in other parts of the world; given that they don't use chlorine to treat their water and they may not have used Acetal fittings, or that they calibrated their crimpers more often and didn't get sloppy about leaving the stuff out in the sun as 'we' seem to have done here B U T ...

PEX isn't PB and Acetal (it was Acetal right) fittings are long gone. Hopefully those using PEX will read the instructions after they learn all they can about the different types made by various manufacturers and the limitations if any. Plastic water line is like the first automobiles, they were feared and said to never be able to make the grade etc.. But plastic is a fact of life as the best bar none product for all things medical and food processing and storage and water line material in the opinon of those in the 'know'.

So who can name me any beverage or food stuff that is packaged etc. in copper other than beer in the brewery? And don't beleive it is due to cost alone. Cost is a factor but it is used because plastic is inert and there is no metal that is inert. So IMO the most learned plumber or home/property owner is not going to remain so if they don't accept plastic water lines as the best there is if they are at all aware of water quality issues. Far too many plumbers are not aware of the libility they face if their copper does cause a water quality issue and they weren't aware it could become one on down the road. The public sees a plumber as THE one to do anything and everything concerning their plumbing AND what is run through it, no?

Gary
Quality Water Associates

Because there are people like you who specilize in water quality I do not deal or work on water filtration products.
It seems everyone has a better mousetrap.
I am a plumber.
Thanks for your expert advice
Southern Plumber

Thanks Gary.

As another, I'll bet if I dug out my dial calipers that the ID differance between any PEX and Copper (not counting fittings, just the tubing) would be only a couple of percent. Not enough to loose a lot of sleep over with todays low flow fixtures.

At least HJ and I seen to agree that the fitting ID is not that big a deal.

The old 9gpm showers might have needed a .50"IDd pipe, but I doubt that todays 2.5GPM are going to suffer from the .47 ID or so PEX.

There is PEX "a" , "B" and "c". A is opnly made by Wirsbo and Rahau. Most others are "b". A and B are ok for regular domestic water. A has a few advatages for streanth way beyond residential use though.

Look through the pex posts on this site and you'l learn alot.

Now you are going to make me measure a piece of 1/2" PEX and then compute its area compared to 1/2" copper, but I doubt that any piece of plastic is going to have a wall that is only about 1/16" thick.

Your analogy to the drink industry is interesting, because the products in the plastic bottles will go "flat" whereas the cans do not. The plastic is permeable and the carbonation escapes. I will not buy soda in a plastic bottle unless I am desperate, and am willing to suffer the difference in taste.

That's only due to beers' storage life being longer than other carbonated beverages but loss of carbonation has nothing to do with my original points.

Gary
Quality Water Associates

You're right that the ID is less in the same size PEX compared to the same size copper, no question. But the same size homerun PEX will deliver all but the same amount of water in gpm. But back to my question, why deliver more water than the fixture can use? What's the reason for wanting to do so or selling the idea that more/bigger is better?

Gary
Quality Water Associates

The answer is not the volume of water being delivered but the velocity of the water in the lines to deliver it. A very small line, given enough pressure, will deliver a lot of water, but the velocity would be such that it could induce noises in the system. It's the difference between a lazy river and a raging stream.

I await your data on the area difference so we can see if we might have to decrease the pressure in the PEX line to reduce the velocity so we don't get any noise but...

Any noise will be less in PEX and than it would be in copper due to the homerun of PEX and its sound deadening ability.

Gary
Quality Water Asscoaites

i have the same stuff it's called Rehau...[www.rehau-na.com]

i had a customer who had the same volume question, pex or copper, i finally got PO ed with him, invited him to my home\ shop and done the experiment. we made an appuratus off my hose bibb, 20 inches drop, 1 90 elbow, 20 ft of straght pipe and a 5 gallon pail. We had a digital stop watch and the results will shock you, .005 seconds slower FOR THE COPPER, final answer.