How PEX is Changing the Commercial Plumbing Landscape

The residential market picked up on the PEX pipe trend first, but the flexible plastic pipe is a good fit for commercial applications as well

The commercial construction landscape is moving at breakneck speed with innovations in designs, materials and artificial intelligence to meet the needs of today’s buildings, which require tighter budgets, shorter timelines, and greater systems performance.

For plumbing applications, there is one building material that the commercial industry is rapidly moving toward — PEX pipe.

For installers in the residential building sector, PEX is well established. It first came onto the scene in the early 1980s when it started being used as a piping alternative to copper and other metal piping systems for radiant floor heating. Within a decade, both the residential and commercial markets began using PEX for radiant applications and found it to be a fast, easy and economic alternative to metal.

In the 1990s, PEX manufacturers began offering a potable piping product approved for plumbing applications. The residential industry went wild for this flexible, durable pipe that was faster and easier to install than copper and CPVC and was also more cost-effective.

But the commercial world still needed convincing that PEX could work for plumbing (and even hydronic-piping applications, such as chillers and fan coil units). The thought that a flexible, plastic piping product could be durable enough for the rigors of commercial plumbing was greeted skeptically, so adoption was slow.

The early 2000s finally saw the first commercial PEX plumbing installs. First, it was used strictly for in-suite applications and involved pipe sizes 1 inch and down. As PEX manufacturers began offering larger sizes up to 3 inches, usage broadened to include risers and mains.

Now engineers and installers are specifying PEX to help meet value engineering requirements and also support those tight production schedules for all types of commercial plumbing (and hydronic piping) applications.

Why the industry is moving to PEX

Professionals who have made the switch will tell you there are three main reasons why the commercial industry is choosing PEX more often: speed, cost and reliability.

In today’s fast-paced information age, where you can get news immediately on your smartphone, the commercial-building landscape is no different. Changes to building designs can happen rapidly, and professionals need a piping product that can move quickly with those changes. Because PEX is flexible and its piping connections relatively fast and easy to make, the product is a great solution to accommodate changes in the field. Plus, with today’s aging buildings, PEX is even more beneficial in re-pipe applications in which existing structures demand minimal invasion for renovation. (Think historically preserved buildings.)

When it comes to cost, every professional in the commercial world agrees — if the cost is attractive, but the product fails, it’s not worth it. PEX has proven to be both cost-effective and durable, a combination that makes it a win-win for engineers, building owners and mechanical installers alike.

Installers are also finding it’s not only the material costs that are reasonable; PEX also helps manage labor costs. Because the flexible pipe requires fewer connections (and those connections are faster and easier to make), it cuts down on labor costs in addition to the bill of material cost for the product.

With materials costing on average up to 30% less than copper, and installs taking up to half the time compared with rigid systems like copper and CPVC (which require more fittings with each change in direction), PEX is proving itself to be a smart solution that installers can rely on for consistent pricing, bidding and installations.

When it comes to worker safety, the lighter weight of PEX also offers benefits. For example, a 300-foot coil of 1/2-inch PEX weighs about 18 pounds, whereas the same amount of copper pipe weighs around 85 pounds. Lighter weight equals easier maneuvering around the job site and can help reduce the risk of injury due to body strain.

As for reliability, every installer has experienced a leak at one time or another. Leaks are the bane of the plumbing installer’s existence. Any material that can help minimize leaks is a plus, so here is a look at all the ways PEX helps minimize potential leaks.

• The flexible pipe can bend with each change in direction, reducing fittings and connections and, in turn, the potential for leaks. Fewer leak points means reduced potential for leaks.
• Certain PEX connection methods actually make it impossible to dry fit a connection. The expansion method of making connections requires expanding the pipe before inserting a fitting. As the expanded pipe shrinks back down, it creates a strong connection onto the fitting. No dry fits mean no potential for an unmade connection blowing off once the water is turned on or the system is pressure-tested.
• PEX is highly resistant to freeze damage. Because of its flexibility, PEX can expand to accommodate frozen water in the system and then contract back down after the water thaws.
• PEX resists corrosion. This means there are no chances of pinhole leaks due to corroded pipe.

Important things to know about PEX before installing it

Before buying products for your first PEX install, keep in mind the following points:

Different PEX types: There are three different types of PEX — PEX-a, PEX-b, and PEX-c, based on their manufacturing methods. The different methods create pipe that is cross-linked to different degrees and uniformity. Rule of thumb: The higher the degree and uniformity of cross-linking, the more durable and flexible the pipe. PEX-a offers the highest degree of cross-linking at around 85%; PEX-b, 65 to 70%; and PEX-c, 70 to 75%.

Different connection methods: Methods for connecting PEX include crimp, clamp, push-to-connect, expansion, and expansion with contraction.

• Crimp connections use a copper ring on the outside of the pipe to hold a smaller-diameter insert fitting that goes into the pipe.
• Clamp connections use a stainless steel ring on the outside of the pipe to hold a smaller-diameter insert fitting that goes into the pipe.
• Push-to-connect uses a fitting, and sometimes an insert stiffener, to support the pipe when the fitting is pushed onto it.
• Expansion expands the pipe to insert a larger-diameter fitting.
• Expansion with compression is a two-step process: expanding the pipe to insert a fitting and then pulling a compression sleeve over the pipe and fitting.

Pipe sizing: PEX pipe is manufactured with a copper tube size (CTS) outside diameter and a standard dimension ratio (SDR) of 9. The SDR is a correlation between the pipe’s outside diameter and wall thickness. This allows PEX to use the same hangers and supports used with copper, as well as any CTS insulations.

Thermal expansion and contraction: PEX pipe expands and contracts at a rate of 1.1 inches per 100 feet per 10°F ∆T. Using a PEX pipe support product (a 23-gauge steel channel)in suspended-piping applicationsin conjunction with fixed anchor points can reduce this expansion and contraction rate to an acceptable level.

Plenum installations: Some PEX is listed to ASTM E84 for use in return-air plenums. Before installing in a plenum, be sure both the pipe and the pipe support is listed for the application.

Through-penetration firestops: PEX must hold the proper ASTM E814 listings for through-penetrations, which can range from one-hour penetrations for combustible wood-frame construction to three-hour, noncombustible listings for steel-frame and concrete construction.

Stick to a single brand: When installing PEX pipe and fittings, it is best not to mix brands. Some PEX pipes and fittings are designed and manufactured to work specifically together for the most optimal performance and satisfaction. Using one brand of pipe and another brand of fitting can potentially compromise the installation and system performance and may also limit the warranty, which can add confusion or frustration if there is a need for service.

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