PEX

While PEX has been used for more than 40 years in radiant heating applications, it’s now getting more traction in commercial hydronic heating and cooling applications as well. Contractors and engineers are beginning to spec and install PEX for distribution piping to various terminal units, such as fan coils, reheat coils, heat pumps, baseboard radiators and chilled beams.

However, while PEX is thoroughly tested and proven in the field, it can sometimes be misunderstood. Many wonder if a plastic pipe can really compete with, let alone outperform, metallic piping in these types of applications.

So, to make it easy, I’ve outlined a few important facts you should know before installing PEX in a hydronic distribution piping application.

All PEX is not the same

Professional PEX products fall into three categories: PEX-a, PEX-b and PEX-c. Of those three, PEX-a, manufactured using the Engel Method, has the highest degree of consistent crosslinking — at 80 percent. This produces a pipe that is more flexible and more durable with thermal and elastic memory properties.

Understanding thermal and elastic memory

Thermal memory is the ability to repair accidental kinks in the PEX-a piping with a controlled heating source, such as a heat gun. The controlled heat quickly eliminates the kink in minutes, while the pipe is restored to its original durability.

Elastic memory refers specifically to how PEX-a piping will quickly return to its original dimensions after expansion. This allows the use of the exceptionally strong, ASTM F1960 fitting connection.

In creating a PEX-a connection, the installer uses a specially made expansion tool to enlarge the diameter of the pipe, so that a fitting with a slightly larger internal diameter can be inserted. The pipe quickly compresses over the fitting, creating a durable connection that actually strengthens over time.

Just as important: Because the fitting diameter is a bit larger than the pipe diameter, “dry-fit” pipe connections are physically impossible. This eliminates the problem when an installer neglects to solder or glue a fitting in a copper or CPVC system, resulting in costly leaks inside the walls of a completed project. An ASTM F1960 fitting requires the connection be fully made, permitting quick visual confirmation.

The difference with expansion fittings

Unlike with metallic pipe, an expansion fitting is actually the strongest part of a PEX-a system. It will not leak. In fact, pull testing shows that even 3,000 pounds of force with over 13 inches of displacement does not compromise the integrity of the ASTM F1960 PEX-a connection. In all likelihood, there would be a catastrophic failure of the building structure before enough force is applied to break that connection.

Using hangers and supports

PEX-a pipe can be hung at similar intervals as metallic pipe. It’s true that other plastic piping systems typically require supports every 32 inches. Some manufacturers, however, offer PEX-a pipe supports — a galvanized steel channel that provides continuous support in suspended-piping applications. This support allows PEX-a to behave just like a metallic piping system in many ways, including hanger spacing: ½-inch and ¾-inch PEX-a pipe can be hung at 6-foot intervals; 1-inch through 3-inch pipe, at 8-foot intervals.

Addressing expansion and contraction

The PEX-a pipe support controls the natural expansion and contraction that occurs as the piping heats and cools. Used in conjunction with manufacturer-recommended installation practices, the pipe support allows PEX-a to undergo an expansion rate equal to or, in some cases, less than that of copper.

Temperature and pressure considerations

PEX-a is rated for continuous operation at 200°F at 80 psi. Any hydronic application with water temperatures at or below this value is perfectly applicable for the product.

Fire-resistant construction ratings

PEX-a is ASTM E84-rated for flame- and smoke-resistance inside a non-ducted, return-air plenum. This also applies to fire stopping. For more information regarding these listings, please contact the manufacturer.

Codes and standards compliance

PEX-a is compliant with all codes and standards that pertain to it, be they in the International family (IBC, IRC, IMC, IPC) or the Uniform family (UMC, UPC, CPC) of U.S. Codes.

To learn more about Uponor’s solutions, visit uponor.com.

Kim Bliss is the content development manager at Uponor. She can be reached at kim.bliss@uponor.com.

While the commercial industry is seeing a growing interest in the use of PEX for hydronic heating and chilled water applications, some professionals are still skeptical that a plastic piping system can actually perform as well as traditional copper and steel.

Let’s turn some of that skepticism into knowledge by answering some of the most common questions about PEX for hydronic piping and detail the facts that will confirm PEX can provide superior performance and reliability while also reducing installation times, project schedules and costs.

What is PEX?

PEX is an acronym for crosslinked polyethylene. It is a flexible, durable, plastic piping material that has been used in radiant heating applications for more than four decades and plumbing applications for the past two decades. PEX has three different manufacturing types to create piping that is crosslinked to varying degrees. PEX-a uses the Engel method which creates piping crosslinked to 80% or more; PEX-b uses the Silane method for piping that is 65 to 70% crosslinked; and PEX-c uses the radiation method to create 70 to 75% crosslinked pipe. The higher the crosslinking, the more flexible and durable the piping.

What are the temperature and pressure ratings for PEX?

Most PEX is rated for the following temperatures and pressures:

• 200°F at 80 psi
• 180°F at 100 psi
• 73.4°F at 160 psi

At 200°F at 80 psi, any hydronic application with water temperatures at or below this value is perfectly applicable for the product.

How do you manage the expansion and contraction of PEX?

PEX expands at a rate of 1.1″ per 100 ft. of pipe for every 10 degrees of temperature change. Using a PEX pipe support steel channel will control this natural expansion and contraction that occurs as the piping heats and cools. In fact, using PEX pipe support in conjunction with strut and strut clamps can reduce the expansion rate to 0.08″/100 ft./10°F, which is actually less than that of copper at 0.11″/100 ft./10°F. And using PEX pipe support with clevis or loop hangers offers an expansion rate of 0.12″/100 ft./10°F, just slightly more than copper.

Does PEX require more hangers and supports than metallic systems?

Using the PEX pipe support steel channel allows PEX to have similar hanger spacing to metallic systems, offering ½” and ¾” PEX pipe at 6-ft. spacing and 1″ to 3″ PEX pipe at 8-ft. spacing.

How is installing PEX better than copper or steel for hydronic piping applications?

Let me count the ways…

• PEX is not an open-market commodity like copper, so its pricing is far more stable over time, making it easier and more reliable to bid jobs.
• PEX can be run in continuous coils up to 1,000 feet in length which results in fewer required fittings.
• Because PEX does not pit, scale or corrode, it requires fewer nitrites, azoles and other chemicals inside the piping system to maintain a static hydronic environment.
• Making PEX connections involves no hot work, eliminating the need for open flame as well as the expense for fire-watch measures on a jobsite.
• PEX connections also eliminate the need for glues, solvents and other dangerous chemicals on the jobsite.
• PEX is significantly lighter than metallic piping (e.g., a stick of copper is three times heavier than a stick of PEX) so PEX is much easier and safer to move around the jobsite.

To learn more about PEX system solutions, visit uponorpro.com.

Kim Bliss is the technical communications manager at Uponor. She holds more than 25 years of writing experience with an emphasis in technical and manufacturing. She can be reached at kim.bliss@uponor.com.

Another product innovation on display at this year’s AHR Expo in Las Vegas was Uponor’s Ecoflex pre-insulated PEX piping system. Here is a closer look at this insulated piping solution.

https://www.youtube.com/watch?v=JEB-J1Kg3Es

On May 21, Uponor North America (Uponor) held an official groundbreaking ceremony to commemorate the company’s seventh expansion in the greater Twin Cities area. The $18 million expansion project will add an additional 88,000 square feet for lean manufacturing, office space and additional manufacturing equipment for producing crosslinked polyethylene (PEX) pipe used in plumbing, radiant heating/cooling and fire safety systems.

Political and community leaders celebrate the groundbreaking for Uponor’s new facility in Apple Valley, Minn., which is pursuing LEED®-Silver certification. From left to right: Tom Lawell, Apple Valley City Administrator; Anna Wills, State Representative; Ed Kearney, Apple Valley Chamber President; Bill Gray, President, Uponor North America; Apple Valley Mayor Mary Hamann-Roland; Ruth Grendahl, Apple Valley City Council Member; Clint Hooppaw, Apple Valley City Council Member; John Bergman, Apple Valley City Council Member; Senator Greg Clausen.

“While this is our latest expansion, it is certainly not our last,” said Bill Gray, president, Uponor North America. “This year marks our 25th anniversary in Apple Valley and we are grateful to the leaders of this local community as well as the state of Minnesota for their support as we continue to grow.”

New Facility
Several political and community leaders were in attendance for the groundbreaking ceremony. Apple Valley Mayor Mary Hamman-Roland and Apple Valley Chamber President Ed Kearney took to the podium to talk about Uponor’s partnership with the city and the importance of the expansion to the local economy.

“Our futures are bright because of our partnerships, and businesses like Uponor are key to the strength and growth of our community,” said Mayor Hamann-Roland.

After the expansion is complete, the North American headquarters in Apple Valley along with the company’s distribution center and resin-processing center in nearby Lakeville will bring the total Twin Cities metro area footprint to 654,738 square feet on approximately 50 acres.

The new facility, which is pursuing LEED®-Silver certification, is expected to be complete at the end of 2015 and will provide more than 100 jobs to the local area over the next few years.