Get to Know PEX

PEX’s flexibility and tolerance of temperatures ranging from below freezing to 200ºF makes it ideal for hot- and cold-water plumbing systems, hydronic radiant heating systems, snow-melting applications, and even ice rinks and refrigeration warehouses.

And those are the characteristics that keep PEX on its upward trend.

Why PEX?
PEX differs from rigid pipe in one obvious way: it is flexible. This makes it easier for you to snake it to different areas of a building. You may have to run more pipe, but there are far fewer fittings, which may attract many plumbers, says Joe Wiehagen, senior research engineer for the NAHB Research Center.

What’s more, all fittings in a PEX system are mechanical, which appeals to some plumbing contractors, Wiehagen says. “There are those that say they can install and solder copper piping in the same amount of time as mechanical fittings,” he adds. “It depends on your preference.” Either way, mechanical fittings allow the PEX system to be pressure-tested immediately.

Fewer fittings and its bending capabilities allow you many different design options: manifold systems, tree and branch systems, remote manifold systems and combinations.

Furthermore, working with PEX is fairly intuitive. “In our experience with plumbers installing PEX tubing is that they get the hang of it after a couple installations,” Wiehagen says. However, more experience is needed when dealing with different manufacturers of PEX tubing because most of them produce the tube and fittings differently, and they rarely match up, he adds.

But you’re not the only one that can benefit. Consider extolling the virtues of PEX to your clients; their decision to implement a PEX system could be a win-win for you. They reap the benefits, you spend less time on service and installation. In fact, cost of home-run plumbing system materials are often less than similar rigid pipe systems, though it depends on system design, house size, your distributor and product availability.

Let your clients know these advantages the next time you have to make a service call:

• PEX is quieter than rigid piping
• PEX has a smooth interior that resists scale build up and corrosion, which later on can affect the pipe flow
• PEX is freeze-break resistant, although not freeze proof
• PEX systems have attractive installation costs when compared with rigid materials

In fact, about half of the new-home starts in California are installing PEX systems, says Mike Cudahy, codes and training specialist at the Plastic Pipe and Fittings Association (PPFA). This partly is due to corrosion of copper pipe in some areas, and because of copper price fluctuations.

Go Green
PEX pipe often is used in green buildings, installed either as a remote manifold or plumbing system, Cudahy says.

In a paralell system, each fixture has a dedicated smaller diameter PEX tube run directly from the hot water source, which means a thinner pipe may be used for the entire connection, reducing the volume in the line. Therefore, waiting times for hot water are reduced and less water is purged down the drain, Cudahy says.

It becomes a cost savings on energy and on water.

Keep It Indoors
PEX, with all its benefits, has drawbacks. One being that it is not suitable for outdoor use because of UV exposure, which causes a reaction with the polyethylene; the maximum UV exposure typically is no more than 60 days, but varies by manufacturer.

Furthermore, there are some chemical exposure concerns to consider, for instance, burying the pipe. However, using PEX for underground water supplies is not ideal, even if UV exposure is decreased.

Alternative
There is another kind of PEX piping that is used in residential and commercial applications and in pressure service on compressed air and compressed gas systems. It is known as crosslinked polyethylene-aluminum-crosslinked polyethylene (PEX-AL-PEX).

PEX-AL-PEX composite tubing resists corrosion and chemicals and capitlizes on the pressure capacity of metal by laminating the aluminum layer between layers of plastic. The tubing also bends for form stability and resists most acids, salt solutions, alkalis, fats and oils, according to the Plastics Pipe Institute’s (PPI) Plumbing and Heating Division.