Cross-linked polyethylene tubing, or PEX if you're into the whole brevity thing, has become one of the major types of conduit for fluid that needs to run from one place to another in a plumbing system. As a result it's probably a good idea for plumbers to add some PEX knowledge to their toolboxes because you can never tell when it might come in handy.
   We tracked down a trio of experts and asked them a series of questions in hopes they would put us wise to the basics of the flexible stuff. Stepping up this month are Dale Stroud, North America business strategy manager for Uponor, Inc., J.P. Fay, associate applications engineer for Viega North America, Inc., and Steve Barrett from Watts Water Technologies.

Reeves Journal: What is your company's best-known brand of PEX tubing and when did you enter the U.S. market with it?

Uponor: Uponor has two PEX brands: AquaPEX for plumbing applications and Wirsbo hePEX plus tubing for radiant floor heating. Equally well known is our ProPEX family of fittings for use with both brands.

Viega: Viega's brand name is ViegaPEX but we also offer ViegaPEX Ultra (which has better UV resistance) so depending on the construction type and potential for excessive UV exposure you have those two choices. We began producing PEX tubing in 1996.

Watts: For our potable product line, Watts uses the brand name WaterPEX. Watts Radiant introduced it in 2003. In 2005, the product line was transferred to the Watts Regulator Group and incorporated into our plumbing and heating product offering.

RJ: Assuming a typical middle-class suburban home (3BR, 2BA), about how much time could PEX save on a repiping job? How about in new construction?

Uponor: There are many variables, so it is difficult to provide a consensus estimate. Although PEX is typically quick to install, the primary attributes that drive its increased use are its properties and characteristics-not just installation ease. For example, PEX does not pit or corrode; therefore, PEX helps keep clean water clean. Also, the inherent flexibility of PEX means that it can be installed with far fewer fittings than rigid piping systems. In particular, the flexibility of PEX is an advantage in re-piping applications. This flexibility allows PEX to be more easily installed in confined spaces and maneuvered around obstructions that are so common in existing buildings.

Viega: [I would refer readers to] the Brighton report conducted by NAHB to address these cost comparisons.

Watts: Repiping is always difficult, and I would estimate that a repipe job with PEX would only save 10- to 15 percent of the time necessary to repipe over a similar rigid system. On new construction, though, PEX can be run in 1/4 of the time and at about 1/3 the overall cost compared to a rigid system. The estimate would vary depending on what piping method (home run vs. tee-and-branch). Home run plumbing systems start at a master manifold, and the pipe is run directly to the end fixture. It uses a lot more pipe, but there are no fittings between the manifold and fixture, therefore, no fittings. The pipe is basically run like electrical wire. Tee and branch systems are run very similar to traditional rigid systems and require a fitting any time a directional transition is made. So the trade-off becomes pipe versus fittings. It really becomes an issue of what the contractor feels more comfortable with.

RJ: Are there any potable water applications for which PEX is not the best choice? Why?

Uponor: PEX is approved for all potable water applications.

Viega: Not that I'm aware of, potable water applications are exactly what PEX is tested and listed for use in. There is a potential for R.O. and D.I. systems (water purification systems) to be used in potable water distribution system that are very corrosive to metallic components. These are safe for PEX tubing and should only be used with plastic fittings, not with metallic fittings.

Watts: Not really. The only cautions would be on a hot water recirculation system where there may be high concentrations of chlorine, but even then, any potable PEX pipe that has a 5006 listing is rated for this type of service. Lastly, as with all plastic pipes, direct, prolonged exposure to sunlight is not a good idea, so running an out door system, say to a swimming pool or to outdoor shower units, is not a good idea unless the pipe is protected from direct sunlight.

RJ: Let's talk fittings-are the fittings and tools used to join PEX to itself or to existing systems standardized across manufacturers? Can I use Co. A's fittings on Co. B's PEX using Co. C's tool?

Uponor: Some fitting systems, such as ProPEX, rely on the "shape memory" of the PEX tube. Thus, only PEX-a tube that is approved for such fittings should be used. Conventional "insert" fittings can be used with all types of PEX pipe, although their reduced inside diameter affects flow characteristics.

Viega: There are specific ASTM standards in place for PEX fitting systems, as long as these fitting systems meet their respective standard and have been tested and listed for use with the PEX tubing manufacturers PEX tubing (marked on the PEX tubing's print line) then you can be assured it's compatible. Generally interchanging one manufacturer's supplied fitting with another manufacturers PEX tubing will be compatible (as long as each PEX manufacturer promotes that particular type of fitting system with their PEX tubing and it is listed and tested for use with it) however there may be a warranty limitation by one of the manufacturers if all the system components aren't supplied by that manufacturer. The tools used for these fitting systems shouldn't be an issue as long as they are designed to make the appropriate connection for that fitting type as out lined in each respective fitting type's standard.

Watts: No. Each manufacturer has preferred system for joining pipe. In the case of Watts WaterPEX, we offer three different methods of joining our pipe. First is the traditional method using a standard brass or poly barbed fitting and securing the fitting to the pipe with a copper crimp ring. Secondly, we offer a similar method using the same fittings and use a stainless steel cinch clamp at the joining method. Both methods require a special tool, however the crimp ring tools are size dependent, while the cinch clamp tool can be used on any size cinch clamp. Lastly, we offer both a poly and brass Quick-Connect fittings. These fittings do not require any tools, and seal on the outside diameter of the pipe and have no flow restriction. They can also be used in concealed spaces and can be used for buried service as well. Most fitting systems can be used across the board. It's always best to check the individual manufacturer's warranty, as it may not cover each type of joining method, and may be limited with other manufacturer's products.

RJ: What are PEX manufacturers doing, if anything, to protect PEX from the DIY market? Bad, handyman-type installations could make for bad P.R. for the tubing, yes? Are there certifications?

Uponor: Some brands of PEX tubing are available in the DIY channel. To date, Uponor has chosen to focus solely on the professional and the plumbing and heating wholesale channel and does not offer its system directly to the DIY-er.

Viega: I'm not aware of any specific activity in the industry to deter this occurrence, but keep in mind there are plumbing codes in place to help promote proper installations of our products. This is no different than some going out and buying car parts from places like AutoZone to fix their own car even though they are not a factory trained mechanic. This, too, can void their manufacturer's car warranties.

Watts: Very little. Most retail stores carry some brand of PEX pipe and joining system, just as they do copper and CPVC. In reality, I'd rather have a DIY'er use PEX over copper or CPVC due to the flame used to solder and the chemical issues with CPVC.

RJ: PEX has come along way toward acceptance over the past few years, with California, the last holdout approving it for potable water use last year. What's next for PEX? Is the era of explosive growth over?

Uponor: The "explosive" growth occurred primarily due to plumber conversions from copper, much of which took place during the housing boom. Thus, as housing slowed, the growth rate of PEX decreased. As the housing market recovers, PEX sales will also increase. The pending requirement for fire sprinklers in one- and two-family homes (beginning in 2011) will also spur considerable growth for PEX. In addition, more and more PEX is being used for plumbing and radiant heating and cooling applications in nonresidential construction, and this trend will create a considerable amount of demand for PEX-based systems. Finally, because of the need to implement green building techniques, PEX will benefit because it exhibits a favorable carbon footprint (as demonstrated by Life Cycle Analysis data). Green building is also creating a great deal of interest in radiant heating and cooling, because of the energy savings that can be realized.

Viega: PEX is a great fit for today's water conditions and plumbing applications, and as one of the largest PEX manufacturers in the industry we stay in tune with water quality issues as well as legislation changes nationally to ensure our products meet the constantly changing requirements/needs.

Watts: I think all of the PEX manufacturers will continue to look for more refined joining methods, and will continue to enhance their pipe compounds with certain attributes. As for growth, that is largely dependent on how the housing market rebounds over the next several years. One thing is certain: PEX is here to stay as a viable, lower cost piping method. I would say that all plumbers have been exposed to PEX piping over the past 10 years and, while many remain traditional in their views as to piping methods, PEX will continue to [be used in plumbing systems] because it's such a sensible, versatile, viable product. It is less expensive to install, safe to work with, and offers long-term system reliability.