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What are the advantages/disadvantages of Pex tubing? How does it compare to copper?

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See similar question: diy.stackexchange.com/questions/1331/… –  gregmac Aug 26 '10 at 20:17

9 Answers 9

up vote 13 down vote accepted

From Pex Information:

  • Flexible PEX tube is manufactured by extrusion, and shipped and stored on spools, where rigid plastic or metal piping must be cut to some practical length for shipping and storage. This leads to several advantages, including lower shipping and handling costs due to decreased weight and improved storage options.
  • PEX plumbing installations require fewer fittings than rigid piping. The flexible tubing can turn 90 degree corners without the need for elbow fittings, and PEX tubing unrolled from spools can be installed in long runs without the need for coupling fittings.
  • Attaching PEX tube to fittings does not require soldering, and so eliminates the health hazards involved with lead-based solder and acid fluxes; PEX is also safer to install since a torch is not needed to make connections..
  • PEX resists the scale build-up common with copper pipe, and does not pit or corrode when exposed to acidic water.
  • PEX is much more resistant to freeze-breakage than copper or rigid plastic pipe.
  • PEX tubing does not transfer heat as readily as copper, and so conserves energy.
  • Water flows more quietly through PEX tube, and the characteristic "water hammer" noise of copper pipe systems is virtually eliminated.
  • PEX plumbing installations cost less because:
    • PEX is less expensive than copper pipe.
    • Less time is spent running pipe and installing fittings than with rigid pipe systems.
    • Installing fewer fittings reduces the chances for expensive callbacks.

If you are only going to be doing a little bit of work, check with your local rental stores, you may be able to rent the tool for a decent price.

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The spool isn't always an advantage -- it means it's going to try to curl back up on you as you're running it. I've seen professionals who use the sticks of PEX, which defeats the advantage of fewer connections, but they said it goes up quicker than gluing PVC, and more forgiving if they need to bend it to route around an obstruction. –  Joe Jul 22 '10 at 15:50
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I've used both spooled and stick PEX, and can say without a doubt that the spool isn't worth the hassle, and it ends up looking like junk -- even the shortest lengths will have a visible curve when you're done. –  Mike Powell Jul 26 '10 at 5:03
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While soldering may still may be the most common method of joining copper pipe it should be noted that alternates such as ProPress and SharkBite exist that do not require solder and flux. –  pdd Jan 3 '13 at 19:40

I know PEX is cheaper (specially considering the rising price of copper), easier to run and less noisy than copper but you have to buy a special crimping tool for the fittings (don't know how expensive the tool is). My only fear would be long term effects depending on water type. For instance I have very hard water (very high calcium content ... I should NEVER have to worry about osteoperosis) and I wonder what will happen 10, 15, 20 years down the road to the PEX pipe based on the minerals in the water.

I'm also not sure if there are any long term health effects from having water run over PVC. Not sure what kind of chemicals leech into the water over time. I'm 99.99% sure it's safe though.

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The tools are often quite expensive. I looked into purchasing a tool to work with PEX that a contractor installed in my house (I've forgotten which brand). It was over $200 for something that was really a simple crimping tool. –  rsgoheen Jul 22 '10 at 14:31
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@rsgoheen There ya have it .... figures they'd do something like that. Jack up the price on a simple tool. As an alternative you could also use the "Sharkbite or Gatorbite" connectors for plumbing. They're snap together plumbing fixtures and can join copper to PVC to clear tubing with no issues. More expensive but no soldier or torches. –  Scott Vercuski Jul 22 '10 at 14:39
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Note that PEX and PVC are two different things. –  DA01 Sep 1 '11 at 17:17
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Two years later - PEX crimping tools can be had for about $80 and that includes with multiple crimp heads. –  The Evil Greebo Jan 3 '13 at 19:34
    
You can get some very basic crimp tools for around $20, but they require vise-grip pliers to close, and would get pretty annoying if doing more than a handful of crimps. –  joshdoe Mar 7 '13 at 17:13

Another advantage to PEX if you're doing a from-scratch installation is that it's typically installed using a manifold at the water source with a run to each faucet. That approach significantly reduces pressure loss at one faucet when another faucet on the same branch is turned on, as often happens with copper plumbing.

You could do the same thing with copper, of course, but it would be prohibitively expensive in time and materials.

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This is a great point. We have PEX with a manifold in our new house. I can turn on practically every faucet with no loss of pressure. –  aphoria Jul 22 '10 at 16:51

There is one huge advantage I see just from reading these posts.

No More Copper Thieves!

I live in New Orleans and had to have my whole system redone because it was cut and stolen.

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That's a sad, but very good point. ;) –  DA01 Sep 1 '11 at 17:17
    
I've heard of people who replaced copper with PEX, where the price for the PEX came out to about the same amount that they got out of the copper. –  Brad Gilbert Oct 28 '11 at 5:45
    
Yeah, but after some of these glowing answers, thieves will be craving PEX pipe. –  Kaz Mar 29 '13 at 5:33

A huge disadvantage with PEX is that it is semi-transparent. If your water supply has nutrients in it and the PEX is installed so that light will get to it, you will find that algae (green), bacteria (black, orange or yellow) will grow inside it. It sloughs off in long, stringy goop similar to the biofilm that grows in diesel tanks that haven't been treated to prevent bacteria growth. Keep it well hidden in walls and away from crawlspace vents where sunlight can penetrate.

diy even has a question submitted on the subject

Keep squirrels away from it, they find it delectable.

Also another advantage listed is that there's no lead. That's true insofar as you stay away from the type that requires brass fittings.

Otherwise, you have a highly flexible, smooth bore water supply system that will allow for using smaller tubing, which can speed up hot water temperature delivery. It's cheap enough that you can do end-run (star) delivery to a central control manifold, typically each run will only have two joints, one at the manifold and one at the the coupling to the shutoff valve. You also don't have a problem with meth addicted copper thieves coming and stripping your house plumbing out if you leave it unattended (summer cottages, another reason iron ain't so bad).

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There are many examples of building products that claimed to be "the wave of the future" and turned out to be utter failures, sometimes dangerous. (polybutylene plumbing, aluminum wiring, and asbestos building products to name a few.) Despite the manufacturer's glowing claims, the actual long-term characteristics and behavior of PEX tubing cannot yet be known.

One of copper's distinct advantages is its long history of solid performance and desirability.

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Another example: theverge.com/2014/1/3/5270310/… –  Bob Jan 21 at 15:15

There is a notable potential downside with PEX (and I'm saying this as someone who's chosen it for his own house).

PEX has the lowest strength of the three most common materials. If I recall my numbers correctly, copper will burst at something over 5,000 PSI. CPVC at around 3,000, and PEX at around 1,200.

Of course, if you get 1,200 PSI in your system to begin with, you've got bigger problems. But still...

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With pex pipe you just need shark bite fittings . Don't require special tools for installation.. shark bite fittings are considerable more expensive than others but you can fix a leak without ever turning the water off if you like

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I'm a huge fan of SharkBites--at least for DIY repairs. I don't know if I'd do a whole house in it (due to the cost) but they are absolutely the best thing for small projects--as well as connecting PEX to existing copper. –  DA01 Jan 14 at 5:49

Copper developes pin holes leaks.... PEX doesn't. Copper's proven track record is pocked with major water leak damage.

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