What do you guys think about cpvc stubouts? I hear cpvc gets brittle over time, and I am afraid they will get bumped and cracked.

I am replacing my home's copper plumbing with cpvc. I try to use cpvc-to-brass drop elbows so I can have a durable brass nipple exposed outside the wall, but with the toilet stubouts, see pictures of my wet wall below, I think I am stuck with cpvc stubouts for two reasons:

1. The 1/2" cpvc pipe between the header and drop elbow will be very short and inflexible, so mounting the elbow to some blocking while trying to align everything will be very difficult. In the past, I have tried using washers as shims under a drop elbow to move it into alignment, but it was still difficult to not put a lot of stress on the plumbing. Perhaps a set of machinist's shims would help, but seems like overkill.

2. A short stiff pipe between the header and drop elbow will not flex much to allow thermal movement of the header.

[i93.photobucket.com]
[i93.photobucket.com]

I always consider installing CPVC a failure. If the copper is a problem, Pex is the next best solution.

DITTO

IMO: both are junk, but, PEX is better junk

chlorinated poly vinyl chloride

or

polyethylene, cross linked

hopefully you could use high density polyethylene, cross linked


ps. hj, don't start

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I didn't say a word, but I WAS thinking them, considering that I have NEVER used either PEX or CPVC for a repipe job.



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Sometimes Pex is just the right material for the job.

yes, when one is attempting to plumb non potable, though code compliant, water

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

obviously any piping system such as pex or cpvc that a homeowner can do themselves thus not needing to hire a licensed, bonded, insured and tattooed union plumber is considered JUNK.
i proudly install pex for all my customers with the exception of commercial applications. the unions could not stop pex in massachusetts so they had to settle for restricting it.
i have installed miles of pex with not one single failure nor leak. IT IS NOT JUNK...

Maybe relocate the tee?

Thank you, Steve. That was creative and could solve the first problem. The branch you added off the tee would give me the flexibility I need to more easily align and mount the drop elbow.

However, the branch you added runs parallel to the header so it wouldn't really absorb any thermal movement of the header. See sketch below. The branch would need to be perpendicular (and at least 6 inches long I guess) to absorb header movement. Notice the branch to the sink stub-outs in this sketch fits these criteria. It will wag back and forth as the header moves.

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I thought about splitting the difference and running the header at an elevation between the low stub-outs (toilets) and high stub-outs (sinks, shower control valves), so each drop elbow would have a decent length branch, but then I thought "I am way over thinking this. The professionals must have an easier solution."

CPVC expands and contracts with temperature 4 times more than copper, so I think you need to allow for that.[www.engineeringtoolbox.com]

If I could, I would go with copper, but for some unknown reason, copper does not last in my neighborhood. Maybe 10 years and it starts developing pin holes. Someday maybe I'll split open the copper pipe I am going to rip out, post the pictures on here, and let you guys do an autopsy report. The two plumbers that gave me quotes to repipe the house both suggested CPVC.

My difficulty with this design is partly due to how the wet wall, between the back-to-back bathrooms, is designed. It is two skinny walls with 1-5/8" deep metal studs spaced apart to allow room for the DWV plumbing. The water supply headers I have been referring to run through one of these skinny walls.

If the wet wall was one wide wall (using 2x6's or 6" deep metal studs), I probably could move the blocking forward or backward between two studs to fit against the drop elbows. Well, at least the skinny metal studs don't feed the termites.

How much expansion are you expecting on a cold water pipe?

You could move the t connection and the stub out for the copper without a problem regardless. The sheetrock is already off, and you aren't trying to match up holes. Moving away from the stud an inch wouldn't hurt a thing

Copper likes slightly alkaline water.

7.4 is perfect


6.5 - 8.5 is its' acceptable range


acidic water eats it

see: [www.epa.gov]


do you have M or L tubing ?

makes a HUGE difference in longevity

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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Quote

...obviously any piping system such as pex or cpvc that a homeowner can do themselves thus not needing to hire a licensed, bonded, insured and tattooed union plumber is considered JUNK.

CORRECT

The HO is not likely to purchase the 'better' professional grade of PEX, nor are they likely to use and calibrate the crimping tool properly.

As for 'union plumber' :

Yep, I was highly trained and was apprenticed to a licensed, insured, bonded master plumber for 5 years.
Guess that makes me incompetent.

Unlike yourself, who works in a state where ANY plumbing performed by a HO is a criminal offence.


HOWEVER

I will assume you had a very bad day, so we shall remain cordial fellow tradesmen.




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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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It is COLD water so any "thermal movement" would be almost infinitessimal.

Bernabeu, I should be ok with pH then. I measured 8 with some litmus paper. We do have very hard water though...lots of calcium. You can see white flakes of it in the water sometime. And, smell the chlorine sometime. I think my water velocities are within range.

I am 99% sure it is the thin stuff, type M. The stuff before that was soft copper.

Type M copper, 3/4", wall thickness = 0.032"
Type L copper, 3/4", wall thickness = 0.045"

0.045"/0.032" = 1.4....so I guess I would get 40% more life out of type L...so 14 years instead of 10 years. That's an improvement, but I was hoping for better.

By the way, I remember the types by thinking......M.artin L.uther K.ing

I remember being told that cooper fittings don't come in different types...they are all type M?? I'd have to check on that again.

Steve, I agree the cold water out of the ground is not going to vary much in temperature. Maybe I am worrying about nothing. But, then I think about the unconditioned air in my attic migrating into my wall cavities. Geez, it never ends.

velocity needs to kept under 4 feet per second (6 is the MAX)

if your home is 'looped' with 1/2 there may be an issue - especially if the pressure is good - counterintuitive but true

the quality of manufacture is equally important to the wall thickness

the tube wall will erode/corrode to a certain extent and then form a self protective 'layer' if thick enough so the wall thickness becomes a geometric curve in relationship to service life

have been retired so I am out of the loop re: brand of copper tubing reqs.

HAVE THE WATER TESTED FOR SULPHUR - sulfur ions are the 'kiss of death' for copper

best of luck, you seem to actually have a clue

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

that's thinking outside the box. nice.

It is easier to remember them by the alphabet j,K,L,M,n, (unless you are doing a DUI sobriety test), and fittings are NOT "type M", they are NOT any "type", and if they are cast brass rather than wrought copper, they are even thicker.



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Thank you for the information HJ and Bernabeu. There is always something to learn. Keeps life interesting.

I didn't even consider the QUALITY of the copper pipe. Good point. I just assumed it was all the same...an expensive commodity.



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some are seamless

some have seams


from personal ANECDOTAL experience - pinholes seem to form along the seam FIRST

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

quote; .an expensive commodity.

As I tell people, "I am not the cheapest plumber, but I may be the lowest priced one", meaning the bottom line is what is important, not how you got there.

In the 50s we were getting a lot of copper tubing from Canada, and their drawing process created a seam. After a fairly short time that seam would develop leaks.

yep

that is what was lurking in my subconscious




ps. if you installed the stuff then you are older than my rocks

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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