PEX and Connector Fittings

GreenDog194March 28, 2012

I would like your advice on what is the most reliable way to use PEX for residential plumbing. Two folks I know (one is my dad) had leaks from a crack in the plastic joint that is used to fit PEX tubes together.

My plumber for repairs says he only uses brass "compression fittings" or "ferrules" to connect the PEX because it is stronger and has a larger diameter hole. He also only uses plastic brackets, not sharp edged metal ones to attach the PEX to the wall because the PEX vibrates some and he doesn't want friction to cause a problem behind closed walls. That all sounds great.

The problem is we are now headed into a to the studs remodel and none of the contractors seem to think there is anything wrong with going with the cheaper plastic connectors; and they don't want to get in trouble with their insurance by telling a plumber sub how to do his job. Plus, each we interviewed wants to use their own plumbers, not my repair guy (who probably does not want to do a whole house anyway because he'd get so backed up with other work).

It does look like I can get the contractors to use real metal pipes to connect to the fixtures. I gather the PEX would attach to the metal, and the metal would come out of the wall and attach to the faucets, etc.

We have radiators that use something that looks like PEX, and all of these joints seem to be metal. OUr contractors say when they do in-ceiling hydronic, the joints will be plastic. I'm worried about that too, but I suppose hydronic heating plumbing is not the same as water plumbing. So this concern may be another question thread.

Sorry my terminology is probably all garbled. I'm trying to understand stuff I know nothing about because I don't want to end up with a $400K remodel job in 5 years to deal with mold and leaks caused by joint plumbing failures like our friend faced. (My dad's fix was not that costly fortunately!)

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Many novices and homeowners seem to have a notion that running PEX is simply a matter of stretching a long plastic hose across the job and putting a fitting on each end, but I can assure you, that is not the case. When done correctly PEX requires much more attention to detail than any of the other piping materials available.

By example, PEX expands or contracts approximately 1" for every 100' of pipe for every 10degF differential in operating temperature. For that reason the standard is to provide 7" of slack for every 50' of PEX tubing. The code prohibits using metal hangers and the hangers or support methods must allow for the movement.

All Fixture stubouts are metal and the connection to the PEX is to be made inside the wall where the PEX will not be subjected to sunlight or UV light sources.

You must use the correct tools to make a PEX joint. Careful here, There are subtle differences between the fitting made by different manufacturers. You must insure that the crimp sleeves your using are made by the same manufacturer as the fitting they are being attached to, and you must insure that the crimping tool is properly adjusted to fit that particular brand of crimp.

ALL CRIMPS must be tested with the appropriate GO/NO GO guage and any fitting that does not pass with the guage must be cut out and redone.

Some fittings require the use of a special expander tool before applying the crimp. (Per MFG spec).

When making a change in direction the minimum radius for the curve is 6x the external diameter of the tubing. By example, the minimum radius for a 90deg bend with 1/2" PEX is a 4" radius. (The installation handbook has a table for the curve radius)

PEX must be located away from heat sources such as chimneys, flues motors or lighting fixtures. (The installation handbook gives a table for required distance).

If installed correctly there is no reason to believe that the plastic will not provide the same service life as the tubing, BUT- the operative phrase is, when installed correctly. If they failed to provide the correct radius on a bend, did not properly support the tubing or if they failed to allow for thermal expansion it could easily result in undo force on the fitting which could cause the cracks such as you described above.

For more complete information you can download a free copy of the 14page PPFA (Plastic Pipe & Fitting Association) "Cross Linked Polyethelene (PEX)Installation Handbook at:

And if you want even more information you can download a free copy of the 147 page PPFA Apprentice Training Manual (Which covers all types of plastic pipe for both pressure & DWV)

Now in regard to the builder wanting to use his plumbers. You must keep in mind that time is money and the GC has to schedule the different trades close so they don't have major delays in the project, therefore a builder likes to stay with a crew that he/she if familiar with. Your man might be able to plumb the house but how long will it take?

When I was going through my apprenticeship they would allow us a maximum of 3 days to plumb a house. One day to run the supply & sewer line from the street to the house and all under slab piping within the house. When the framing was up we then went back for a second day, inwhich we had to run all the water distribution piping and DWV piping that would ultimately be under floors or behind walls. As the house neared completion we then went back for a third day to do the Trim out, where we set all the fixtures and made all the final connections, pressure tested and got our final inspection. Believe me, I have worked a lot of 16 & 18 hour days to make it all come together on schedule, but we had to finish because we were already scheduled on another job the next day.

    Bookmark   March 28, 2012 at 4:00PM
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Thanks so much for all this information. I think my question really boils down to should I care if a plumber uses PEX with Wirsbo fittings (the plastic ones, or some other brand that uses plastic fittings, hopefully BPA-free) or PEX with REHAU fittings (the metal ones, and the kind my current plumber feels is a better product). Sure, both meet the plumbing code, but which system would you rather have in your house, and why?

    Bookmark   March 28, 2012 at 6:35PM
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I think the plastic & copper fittings are both quality products and I am sure they could present a sound argument for both.

When I do run PEX I strictly use metal fittings but that is because I use a Cordless Power Crimper and the manufacturer specs say it is set up for metal fittings and crimps.

Now when you ask which I would put in my house the answer is simple,,


all water distribution lines in my house are copper and all concealed joints are silver brazed instead of soldered, with the exception of the fixture supply tubes from the fixture stop to the fixture, which are plated brass tube.

    Bookmark   March 28, 2012 at 8:40PM
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"all water distribution lines in my house are copper..."

That statement speaks VOLUMES when spoken by a plumber.

I'm not anti-technology, but it seems that every 10 or 20 years there's a new fantastic plastic introduced for plumbing and then 10 or 20 years later that plastic that will revolutionize the plumbing is followed up with class action lawsuits and expensive re-plumb and repair jobs.

Regardless of the price copper seems to stay and stay and stay if the water conditions are right.

    Bookmark   March 29, 2012 at 4:53PM
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We just can't afford the copper piping for the whole house, unfortunately. There is always the gold standard. Given that we need to compromise, it seems that I would prefer the REHAU method with PEX because it uses metal fitting (lead free), rather than another method that uses all plastic.

Would you agree?

I realize that the answer I get may differ depending on the perspective of the person answering. I'm learning that when asking about quality, I should ask tradesfolk who do repairs, rather than construction / remodels. Those who make a living on repair work need to have their work last or they will not stay in business. Construction work -- there is always hope for another job, and what homeowner can even track down the sub on the job 5 years prior. That is an aside, but I mention it because would not be surprised to learn that for plumbers who do repair 70% use REHAU (or copper), and for plumbers that do construction 2% use REHAU and none use copper.

    Bookmark   March 29, 2012 at 9:07PM
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The bitterness of less quality lingers long after the sweetness of lower cost is gone... or something like that.

There's nothing quite like wet sheet rock.

    Bookmark   March 29, 2012 at 9:39PM
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"Those who make a living on repair work need to have their work last or they will not stay in business. Construction work -- there is always hope for another job, and what homeowner can even track down the sub on the job 5 years prior."

Taht statement is totally ridiculous...Go to the county courthouse and have them pull the Occupancy Certificate.

1. The C.O. will list all the trade permits and date of inspection from ground breaking until turnkey, and the original installer is listed on each trade permit.

2. Real plumbers do new construction, rehabs & service work whereas those who only do repair work are generally wanna be plumbers with just the bare essentials of trade credentials and often have neither a plumbing license or the proper insurance to be working on your house.

    Bookmark   March 29, 2012 at 10:58PM
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Thanks for setting me straight. I'm showing my bias against those instant developments and highrise condos that fall apart or go unoccupied.

Talking to the plumbers doing the bids, I'm learning much about the pride in their work and their expertise.

Perhaps it is not the wand, it is the magician!

    Bookmark   April 4, 2012 at 8:44PM
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It's the beautiful assistant...

    Bookmark   April 4, 2012 at 8:52PM
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I am not resistant to change, I just fail to see any advantage by using PEX over Copper.

First off, contrary to the popular belief, when PEX is run correctly according to code and manufacturers specs it requires much more attention to detail and labor than does copper. (but then the operative phrase here is, "when run correctly")

2.When you factor in the cost of fittings there is very little savings by using PEX, especially if you elect to use the PEX manifold system.

3.technically speaking, there is nothing in code that would prevent one from running copper in a manifold configuration.

4. Friction head losses per linear foot are nearly 3 times as high in PEX as it is in copper. Don't believe it? Check the facts for yourself, you can download both PEX and copper Friction head loss tables free in PDF format, but for illustration here are some examples:

1/2" type L copper @ 4gpm = 0.106psi/ft loss
1/2" PEX @ 4gpm = 0.204psi/ft loss

1/2" type L copper @ 5gpm = 0.161psi/ft
1/2" PEX @ 5gpm = 0.308psi/ft loss

Many homeowners are impressed by the manifold system with one central location to turn the water off, but I find it a total PITA when I am attempting to work on a lavatory faucett on the second floor, but I have to go all the way down to the basement to turn the water off, instead of simply reaching down under the sink and turning the fixture stop off (but then many local codes require that you must still install the individual fixture stops.)

The manufacturers specifications state that PEX systems MUST BE sanitized at least once every three years, but does anyone tell the homeowner? On the other hand, copper forms a layer of copper sulphate on the inside of the pipe, which is one of the best anti-bacterial substances known to man.

Now, while there is some monies to be saved when installing PEX in the common main @ branch configuration in most instances if you elect for a PEX manifold system, due to the increased amount of tubing and fittings required most plumbers are actually bidding the PEX manifold system for the same price as copper.

    Bookmark   April 4, 2012 at 11:35PM
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"The C.O. will list all the trade permits and date of inspection from ground breaking until turnkey, and the original installer is listed on each trade permit. "

Go try to find the folks listed on any paperwork more than about 2-3 yeas old.

Around the Washington, DC area the turnover is so high it is ridiculous.

Housing costs are so high most of the tradesmen live hours away.

I know one group of plumbers (3 guys) that rent an apartment they share and only drive 2-3 hours home for the weekend.

Finding any of them a few years from now would probably take hours after finding what address their license is registered at presently.

This is not a 'small town' type area with long term tradesmen.

    Bookmark   April 5, 2012 at 11:07AM
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This is an interesting discussion and thanks for your post. No doubt, copper and galvanized pipes are being replaced with newer plastics in my house when problems arise. Only offer I've had for copper is on the water line to my refrigerator when my spouse ran over the pre-existing plastic one which predated our purchase.

So you prompted my learning some on PEX (cross linked polyethylene where the X stands for crossed). My mind tells me copper would be preferable, as plastics are xenoestrogenic, meaning they are are a type of xenohormone that imitates estrogen. This is not good for at least 50% of our human population, and bisexual amphibians are increasingly common.

I found one connector that may be of benefit to you and will up load it below. It is on Wikipedia under PEX, pictures on the lower right. Wikipedia notes it as a PEX compression fitting makes it possible to join copper and PEX pipes by simply pushing them together for a watertight fit. Perhaps it will offer a compromise for you.

brickeyee: I'm in the Washington DC area too and in need of a good plumber for an old house. If you have a name, perhaps you might share one. thanx.

Here is a link that might be useful:

    Bookmark   April 6, 2012 at 10:15PM
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"plastics are xenoestrogenic"

Only certain plastics.

Ascribing a characteristic to "plastics" as a general class never works well since there are millions of formulations, and probably billions if you want to consider all the additives available.

    Bookmark   April 7, 2012 at 10:15AM
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"SparkingWater" thanks for your photo link. This seems to be a photo of the Rehau fittings that prompted my post. Here is more about it, but perhaps not a definitive link:

I am learning that these Rehau fittings are having problems with "zinc-ification" and have had to be replaced. Again, here is a link that may not be definitive, but at least explains the problem: If it is not one thing it is another.

As an alternative, it seems that for connector fittings the Wirsbo, now Uponor is the system of choice these days for PEX (at least from my limited interviews here in Seattle). Who knows down the road what will happen. Here's more information about Uponor:

here is an interesting link from apparently an inspector's view:

I do have concerns about long term health exposure using PEX. I hope someone can point me to more recent data, but here is an analysis which reports that PEX likely leaches substances harmful in drinking water, including BPA, but the issue has not been fully studied:
No filtration system seems to be able to filter out BPA.
So, although PEX is approved in CA building codes, the issue of safety in drinking water was not fully vetted (perhaps a lawsuit addressed this issue, but I have not researched that).

(Are Upanor fittings made in Germany so no BPA?? Is that a crazy assumption?)

I think the gist of the message on this discussion link is "go with copper". Oh boy, that I could! I will go ahead and get a quote for copper, but I bet it will really blow our budget. Still, I have young children and I do not want my choice on plumbing to put them at any risk, knowing that perhaps at this point the risks have not been fully evaluated yet.

Of course, the issue that really started this thread for me was reliability of PEX fittings...

Here is a link that might be useful: BPA in PEX?

    Bookmark   April 7, 2012 at 4:45PM
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