It’s well-known that copper (2″ and down) has dominated the hydronic heating and cooling market for decades. However, with the need to value engineer projects and still ensure high quality while staying on schedule, professionals in the industry are looking to new materials for solutions to improve profitability, increase system performance and meet the tight deadlines that always accompany commercial projects.
Enter PEX.
PEX is a durable piping material that is increasingly proving its value in commercial hydronic applications for transporting water to terminal units such as chilled beams, fan coil units, baseboards, radiators, hydronic VAV (variable air volume) reheat coils and radiant manifolds. Its flexibility, corrosion-resistance, price stability and overall performance make it superior to copper in many ways. In fact, more than 17 billion feet of PEX has been installed in plumbing, heating and cooling applications around the world — so quite a large number in the industry have already experienced the proven performance of PEX.
However, some have a perception of PEX pipe as being a cheap and flimsy alternative to copper. They don’t recognize it for being the durable, commercial-grade product that more and more engineers are specifying and more and more mechanical contractors are installing in hydronic applications.
PEX is showing its versatility for hydronic piping systems in both new construction and retrofit applications, such as The Wick Tower and Homewood Suites restoration projects or The Homestead at Rochester and Episcopal Homes senior housing expansion projects.
For those that are unfamiliar with the product, there are three different types of PEX (based on the crosslinking manufacturing method) — PEX-a, PEX-b and PEX-c. PEX-a is considered the superior PEX in the industry due to its higher crosslinking which makes it more flexible and durable compared to the other two forms.
PEX-a is regulated by ASTM F876, which denotes temperature and pressure ratings of 200°F at 80 psi, 180°F at 100 psi and 73.4°F at 160 psi. These values are well within the range of operation for the vast majority of hydronic systems. (This is especially true with the industry’s focus on energy efficiency and the trend to use higher water temperatures in cooling and lower water temperatures in heating.)
Bridging most differences between PEX-a and copper in hydronic applications is the PEX-a Pipe Support, a galvanized steel channel that provides continuous support in suspended-piping applications. The supports permit hanger spacing similar to copper pipe, reducing the required number of hangers by half. And since fewer hangers mean lower material and labor costs, use of the PEX-a Pipe Support results in a less-expensive installation.
PEX-a Pipe Support also controls the natural expansion and contraction that occurs as PEX piping heats and cools. PEX-a has a free-body expansion rate of 1.1 inches per 100 feet per 10⁰F ∆T, or 10 times that of copper. Installing anchors every 65 feet and using PEX-a Pipe Supports allows PEX-a to function much like a copper system.
The support also addresses aesthetic concerns some may have with PEX. Commercial contractors and building owners typically expect long, evenly spaced, rigid pipelines running through their hydronic systems. Supporting the PEX resolves this by reinforcing and covering the pipe.
So if you’ve heard about (or seen) PEX in a hydronic piping application and are curious if it can work for your next project, take a look at what PEX can do for you. You might just be the next one to experience the proven performance of PEX.
Kim Bliss is the technical communications manager at Uponor. She can be reached at kim.bliss@uponor.com.
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