The Contractor’s Checklist for Installing Commercial PEX Systems

Here’s a guide that can be consulted the next time you’re tackling a PEX installation on a commercial job site

The Contractor’s Checklist for Installing Commercial PEX Systems

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With PEX pipe use expanding across the commercial building space for domestic water applications, more and more contractors are switching to the product due to its durability and ease of use.

Here’s a checklist to ensure you have all the information needed to do the job safely, effectively and profitably when it comes time to install a commercial PEX plumbing system.

Types of PEX

Make sure you’re familiar with the characteristics of the type of PEX you’re installing before you begin the job. Not all PEX is the same.

  • PEX-a is manufactured with the highest degree of crosslinking (80-plus percent), which means it’s the most flexible with the tightest bend radius. You can repair accidental kinks with a shot of heat from a heat gun (which is not possible with the other two types of PEX). And while PEX-a is specifically designed to connect with ASTM F1960 cold-expansion fittings, you can also use crimp, clamp and push-to-connect fittings.
  • PEX-b provides 65 to 70 percent crosslinking for a stiffer product. For connections, use ASTM F1807 (metal) and ASTM F2159 (plastic) insert fittings with a copper crimp ring, ASTM F2098 stainless steel clamp rings, or ASSE 1067 push-to-connect fitting styles.
  • PEX-c offers 70 to 75 percent crosslinking for a midrange of flexibility. Fitting methods include crimp, clamp and push-to-connect.

Regulatory Compliance

Make sure the PEX product you’re installing meets the applicable requirements for your jurisdiction.

  • Product may need to meet some or potentially all of the following building codes: International Building Code (IBC), International Plumbing Code (IPC), Uniform Plumbing Code (UPC) and National Standard Plumbing Code (NSPC).
  • Product may need to meet some or potentially all of the following standards and listings: ASTM F876, ASTM F877, ASTM F1960 (exclusively for cold-expansion fittings), ASTM F2023, ASTM F2657, ASTM E84, ASTM E119, ASTM E814, AWWA C904, NSF/ANSI 14, NSF/ANSI 61, NSF/ANSI 359, NSF/ANSI 372 and ASME A112.18.1.

Fitting Connections

Depending on the pipe type, make sure you’re installing the fitting system properly.

  • For ASTM F1960 expansion fittings, square-cut the pipe for a straight cut, then slide on the expansion ring. When sliding on the ring, ensure it overhangs the pipe 1/8-inch, so it doesn’t slide down the pipe when you start the expansion process. Some rings have a stop edge on one side, so it can only go on the pipe one way. The stop edge ensures you have the proper 1/8-inch overhang over the pipe. After the ring is properly on the pipe, insert an expander tool to expand the pipe and ring. After expanding, insert the fitting. As the pipe and ring shrink back to their original size, it creates a strong, durable connection that can never be dry-fit, eliminating the risk of potential leaks from incomplete connections.
  • For copper crimp rings, square-cut the pipe for a straight cut, then insert the fitting onto the end of the pipe. Slide the ring over the end of the pipe at the proper position where the pipe and fitting overlap (position depends on manufacturer). Use a crimp tool to compress the ring until the tool stops, then use a go/no-go gauge to verify the connection is made properly.
  • For stainless steel clamp rings, the process is very similar to copper crimp. First, however, you must calibrate the crimp tool. From there follow the same instructions as copper crimp rings: square-cut the pipe for a straight cut, insert the fitting into the pipe, slide the ring over the end of the pipe, and compress the ring until the tool stops.
  • For push-to-connect fittings, some manufacturers require a stiffening sleeve inside the PEX pipe prior to making the connection. After inserting the sleeve, push the pipe into the fitting per the manufacturer’s instructions.

Minimum Distance Between ASTM F1960 Expansion Fittings

A minimum distance is required between ASTM F1960 expansion fittings to protect the fittings from damage and also prevent leaks.

  • 1/2-inch pipe size requires 2-inch minimum cut length of pipe.
  • 3/4-inch pipe size requires 3-inch minimum cut length of pipe.
  • 1-inch pipe size requires 3 1/2-inch minimum cut length of pipe.
  • 1 1/4-inch pipe size requires 4 1/2-inch minimum cut length of pipe.
  • 1 1/2-inch pipe size requires 4 1/2-inch minimum cut length of pipe.
  • 2-inch pipe size requires 6-inch minimum cut length of pipe.
  • 2 1/2-inch pipe size requires 7 1/2-inch minimum cut length of pipe.
  • 3-inch pipe size requires 9-inch minimum cut length of pipe.

Bending PEX-a Pipe

Use the flexibility of PEX-a to eliminate unnecessary connections when making a change in direction. Refer to the guidelines below when bending the pipe.

  • 1/2-inch pipe offers 3 3/4-inch minimum bend radius.
  • 3/4-inch pipe offers 5 1/4-inch minimum bend radius.
  • 1-inch pipe offers 6 3/4-inch minimum bend radius.
  • Use bend supports to help make 90-degree rigid bends for 1/2-inch, 3/4-inch and 1-inch pipe.
  • To alleviate stress on fittings, allow two times the pipe’s outside diameter as minimum distance before changing direction. For example, 1/2-inch pipe has an outside diameter of 0.625-inch, so the minimum distance would be 1 1/4-inch.

Hangers and Supports

Installation practices vary for horizontal and vertical applications.

  • For horizontal installations, use copper tube size hangers.
  • To support bare PEX, space hangers between 32 inches and 48 inches apart, depending on the applicable code.
  • Use steel PEX pipe support channels to increase hanger spacing 6 feet to 8 feet. (Note: Using pipe supports also reduces expansion and contraction rates of PEX.)
  • For vertical in-wall installations, space hangers 5 feet apart.
  • For vertical risers running between building stories, install copper tube size clamps at the base of each floor and include an iron pipe size support as a midstory guide.
  • For hot-water vertical risers, add an extra clamp at the top of every other floor.
  • For cold-water vertical risers, add a clamp at the top of every fourth floor.
  • Use anchor points every 65 feet for domestic hot water.
  • Use anchor points every 150 feet for domestic cold water.

Public Fixtures

PEX-a pipe can reduce surge pressures in public fixtures by 18 to 40 percent, compared with metallic piping. PEX-a also has superior acoustical properties, absorbing 10 to 100 times more sound (measured in decibels per centimeter) than metal piping. When installing PEX for these types of applications, keep these rules in mind.

  • Keep the PEX-a header higher, allowing for longer, sweeping bends down to the fixture connections.
  • Most codes require hammer arrestors for fast-acting valves, regardless of pipe material.

Plenum Installations

Some PEX is approved for use in return-air plenums (unducted ceiling spaces for air circulation). Refer to the following guidelines when installing PEX in a plenum.

  • Ensure the PEX is listed to ASTM E84 for use in return-air plenums.
  • If using a steel pipe support channel, ensure the channel is also listed to ASTM E84.
  • If using pipe supports is not an option, ensure the pipe is covered by an ASTM E84-listed insulation.
  • Smaller-diameter pipe sizes (1/2-inch and 3/4-inch) do not require insulation or pipe support.

Through-Penetration Firestops

Some PEX is also approved for use with through-penetration firestops.

  • Ensure the PEX pipe you’re installing carries the proper listings through ASTM E814 for through-penetrations.
  • Listings range from one-hour penetrations for combustible wood-frame construction to three-hour noncombustible listings for steel-frame and concrete construction.
  • Listings are maintained by various firestop manufacturers, such as Hilti, 3M, Specified Technologies, Inc. (STI), and RectorSeal.

Underground Distribution

Refer to the following requirements when installing PEX in an underground distribution application.

  • Ensure the PEX is listed to AWWA C904 for water service and is rated for direct burial.
  • Prepare the trench properly. For flat, rock-free soil, install PEX directly on the trench bottom. For rocky, muddy soil, pour a granular material (not to exceed 3/4 inch in particle size) to provide a stable base.
  • Use 1-inch insulation to overcome soil compression.

Pressure Testing

PEX-a pipe is approved for air and hydrostatic testing.

  • Before testing, allow the system pressure to stabilize and always test in accordance with local codes.
  • If conducting a hydrostatic test, do not allow the water-filled piping to freeze.
  • Expect slight fluctuations of pressure due to ambient temperature changes.
  • Condition the PEX to 1.5 times the test pressure, then allow the pressure to drop to 10 psi before repressurizing to 1.5 times the test pressure. Repeat for a duration of 30 minutes. Then, quickly relieve the pressure to actual test levels, close the valve, and start the pressure-test timer after observing a slight rise in pressure.

System Flushing

Refer to the following guidelines for flushing the system after install.

  • Flush the system with clean, potable water to remove any construction debris.
  • If required by code, disinfect per AWWA C651-86 with either a chlorine solution of 50 ppm for 24 hours or a chlorine solution of 200 ppm for three hours.
  • Be sure to flush the system with potable water after chlorine disinfection.

About the Author

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



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