Frequently asked questions

PEX is an acronym for polyethylene (PE) that is crosslinked (X). It is a highly flexible, durable and non-toxic pipe for use in plumbing, radiant heating and cooling, hydronic heating and cooling, and fire sprinkler systems.

In 1968, German inventor Dr. Thomas Engel developed the method to chemically crosslink polyethylene, and in 1972, Wirsbo (now Uponor) introduced Engel-method PEX (called PEX-a) to the European market. In 1984, PEX-a was brought to North America initially for radiant floor heating and then for plumbing systems. Today, more than 17 billion feet of PEX is installed worldwide for heating, cooling, plumbing and fire safety systems.

Uponor PEX plumbing systems, branded Uponor AquaPEX®, have been in service since 1993.

Uponor PEX plumbing systems use flexible PEX pipe and innovative ProPEX® expansion fittings to create a solution that minimizes connections, resists corrosion, pitting and scaling, offers greater resilience in freezing conditions and lasts the life of the structure.

Uponor’s unique ASTM F1960 ProPEX connection method capitalizes on the shape memory of PEX-a. ProPEX connections use one simple tool to make fast, strong, solid connections that hold tight in strength tests with up to 1,000 pounds of force. ProPEX connections eliminate the need for torches, glues, solvents or gauges, and they cannot be dry fit, so there is never a question whether the fitting is made. ProPEX connections are available in both lead-free (LF) brass as well as engineered polymer (EP).

Making a ProPEX connection is simple: just place an expansion ring on the end of the pipe and use an expansion tool to expand the pipe and ring. After expanding, insert the larger-diameter fitting. As the pipe and ring shrink back down, it creates a solid, strong connection. In fact, ProPEX connections are the only PEX connection method that actually get stronger over time.

Yes, there are three different manufacturing methods for producing PEX 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. PEX-c uses the radiation method to create 70 to 75% crosslinked pipe. The higher the crosslinking, the more flexible and durable the piping.

Crosslinking relates to the molecular bond inside the pipe. The higher, more uniform crosslinking in Uponor PEX-a pipe means a more durable, flexible and damage-resistant pipe with faster, stronger expansion connections that hold tight.

Because of its flexibility, Uponor PEX can bend with each change in direction, reducing the number of required fittings for faster installations and greater system performance. Uponor PEX will not corrode, pit or experience scale buildup, and its ability to expand and contract offers greater durability in freezing conditions. Also, because you have to first expand the pipe and expansion ring to make a ProPEX connection, it is impossible to dry fit that type of connection. Additionally, because Uponor PEX is not a traded commodity, it provides stable pricing (and helps avoid theft on the job site that often happens with copper).

Uponor AquaPEX pipe and ProPEX fittings are available in sizes up to 3".

In accordance with ASTM F876, the minimum hydrostatic burst pressure for PEX pipe at 73.4°F (23°C) is 480 psi for ½" pipe and 475 psi for ¾" pipe and larger. Uponor PEX-a pipe undergoes extensive quality testing daily to ensure it exceeds the ASTM F876 industry standards for burst pressures and consistently tests to nearly double the burst pressure requirement.

Uponor PEX-a pipe expands at a rate of 1.1" (27.94 mm) for 100 ft. (30.48 m) of pipe for 10°F (5.56°C) temperature change. Using PEX-a Pipe Support with struts, strut clamps, clevis hangers or loop hangers will help control the expansion/contraction of the pipe to levels similar to that of copper pipe.

Yes, Uponor PEX has undergone decades of rigorous testing. In 1973, Uponor (Wirsbo) submitted PEX pipe samples to an independent laboratory. For three decades, these samples underwent continuous hydrostatic tests at extreme temperatures and pressures — up to 203°F (95°C) and 239 psi (16 bar). At the conclusion of the tests, not a single piece of Uponor PEX experienced any breakdown or failure.

Plumbing systems use Uponor AquaPEX pipe while radiant floor heating systems typically use Wirsbo hePEX™ pipe, which features an oxygen-barrier layer to protect ferrous components in the radiant system.

The bend radius of Uponor PEX is six times the outside diameter of the pipe.

Yes, due to the pipe’s thermal memory, you can repair a kink with a shot of heat from a heat gun. Note this is only possible with PEX-a pipe. You cannot repair kinks in PEX-b or PEX-c pipe.

All PEX manufacturers are required to test their pipe’s resistance to hot, chlorinated water and list the PEX designation on the pipe’s print stream. Uponor PEX-a pipe meets the highest requirement for chlorine resistance at end-use conditions 100 percent of the time at 140°F (60°C).

Uponor AquaPEX white pipe has a one-month UV resistance. Uponor AquaPEX red and blue pipe have a six-month UV resistance.

Uponor AquaPEX pipe and ProPEX fittings are ideal for use in a variety of plumbing applications, including in-slab, underground, risers, mains, in-suite and graywater applications.

Uponor Logic is a plumbing design and layout that maximizes the flexibility of PEX pipe to reduce connections while incorporating multiport tees located near fixture groupings to limit the amount of pipe and connections needed and improve installation efficiencies. This installation method uses considerably less pipe than a home-run layout, with just a few more connections, and it requires significantly fewer connections compared to a trunk-and-branch installation.

An Uponor Logic design uses a main line going to a multiport tee with distribution lines going out from the tee. These individual lines extending from the single multiport tee provide water to all fixtures in a single or adjacent grouping.

A multiport tee is a long, engineered polymer tee with multiple outlets. However, they are not classified as a manifold, so there is no requirement for access behind a wall. Multiport tees greatly reduce connection points due to their ingenious design. For example, six regular tees require 18 connections, but a flow-through multiport tee with six outlets only needs eight connections (six connections for the ports, a main flow-through inlet and a main flow-through outlet). Additionally, multiport tees require much less space to install.

Yes, Uponor has ProPEX water meter fittings and valves for direct connection to water meters sized ⅝" to 1".

Yes, Uponor offers a comprehensive line of lead-free (LF) brass press fittings, sweat fittings, threaded fittings, stub-outs, valves and wall boxes that meet lead-level criteria at or below 0.25% by composition and exceed the United States Safe Drinking Water Act.

No, Uponor PEX pipe and EP fittings do not contain any lead.

To insulate connections when installing Uponor AquaPEX pipe, simply pull the insulation over the ProPEX ring, leaving only the fitting body uninsulated. If fitting insulation is necessary, insulation kits are available in the industry.

Support PEX with the same copper tube size (CTS) pipe hangers or supports used for metallic pipe. For 1" and smaller PEX, horizontal support spacing is 32"; for 1¼" and larger PEX, it is 48". (Note that some codes, as well as the National Plumbing Code of Canada, only allow for 32" horizontal support spacing regardless of pipe size, so be sure to check local codes for verification.)

Maximum support distance is 8 ft. (2.4m) for all pipe sizes. Support fittings 1½" and smaller within 12" (0.3m). Clamp the pipe at a maximum of 32 ft. (9.7m).

For all pipe sizes, support Uponor PEX pipe every 5 ft. (1.5 m) in vertical applications.

For cold-water risers, use a CTS clamp at the base of each floor as well as a clamp at the top of every fourth floor. For domestic hot-water risers, clamp at the base of each floor and the top of every-other floor.

Uponor PEX-a pipe is approved for installation in plenums and carries a three-hour fire-resistive rating. Refer to the firestop manufacturer for approved through-penetrant applications with PEX pipe.

Uponor PEX pipe is approved for direct burial in soil or concrete. For faster, easier installations, use Pre-sleeved Uponor AquaPEX pipe. The corrugated sleeving provides added protection for installations in concrete slabs or soil.

Yes, you can bury pre-insulated Uponor AquaPEX provided the pipe is away from contact with groundwater. Although the water will not compromise the integrity of the pipe or insulation, it will have a detrimental effect on the insulating value of the insulation.

Uponor ProPEX EP fittings are approved for direct burial. If using brass fittings, cover with a minimum 6-mil poly wrap.

For residential applications: Use a mixture of water and air (or air when allowed by local code), and pressurize to 25 psi (1.7 bar) above working pressure, or 100 psi (6.9 bar).

For large commercial applications: Fill the system with potable water, air or a combination of both. Then, condition the pipe to 1.5 times the test pressure or 120 psi (8.2 bar) for 30 minutes. After 30 minutes, release excess pressure until you reach desired test pressure [80 psi (5.5 bar) recommended].

Radiant floor heating is a very comfortable, highly efficient form of heating a space. The system circulates warm water through flexible PEX pipes installed under the floor (or occasionally in walls or ceilings). The heat from the pipes radiates evenly up through the floor to warm people and objects in the space. This type of heating is exceptionally energy-efficient and helps support improved indoor environmental quality (IEQ).

Because a radiant system does not use fans or blowers to circulate dust, dirt and other allergens, it can greatly improve indoor air quality in a space. Additionally, warm radiant floors eliminate the need for carpeting, which can be a breeding ground for dust mites, a common cause of allergic respiratory disease.

Unlike traditional forced-air heating systems that just warm the air, radiant heating warms the floor and objects in contact with the floor. The entire floor distributes a consistent, even and quiet heating. There are no drafts and radiant floor heating takes the chill out of cold tile, marble and wood floors. Plus, occupants are typically more comfortable with radiant floor heating at a lower thermostat setting than with forced-air heating at a higher thermostat setting, making radiant more energy-efficient as well.

Uponor (formerly Wirsbo) has been making PEX pipe for radiant floor heating since 1970, longer than any other PEX manufacturer. We were also the first to bring radiant floor heating to North America in the mid-1980s.

Radiant cooling works similar to radiant heating with water circulating through PEX pipes embedded in the floor, walls or ceiling. However, with radiant cooling, the cool water circulating through the system absorbs heat radiated throughout a space to cool people and objects in a room.

Radiant cooling works best where the air handling system in the structure can control the wet bulb gain. Most often, this occurs in commercial buildings. However, in some climates where relative humidity is lower and in larger residences where relative humidity can be controlled, radiant cooling is an additional strategy to lower cooling costs.

Using an Uponor radiant heating and cooling system in a commercial design can help achieve LEED® points in the areas of Energy & Atmosphere (EA), Indoor Environmental Quality (IEQ) and Innovation in Design (ID).

No, one system can both heat and cool, and in some climates in North America, the system may do both throughout the day as well as be designed to transport heat from one side of the building or the other.

A radiant system can use either an oxygen-barrier pipe or a non-oxygen-barrier pipe. Wirsbo hePEX™ pipe features an oxygen-barrier coating technology to protect ferrous components from corrosion in a closed-loop hydronic radiant system. Uponor AquaPEX is a non-oxygen-barrier pipe that is typically for plumbing applications, but can be used in radiant applications where the system contains no ferrous corrodible components or where any ferrous components are isolated from the pipe.

Yes, because water has the capacity to transport energy 3,500 times greater than air, a hydronic radiant heating and cooling system is much more energy-efficient compared to a traditional forced-air HVAC system.

Most radiant heating systems use boilers (natural gas, electric or oil) for the heat source. There are also alternative heat sources, such as geothermal and solar, which pair well with the energy-efficiency of a radiant heating system. Additionally, smaller residential installations can also use hot-water heaters, wood-fired boilers or pellet stoves as heat sources.

Yes, however the ducts can be smaller which can save on structural height. Ventilation is necessary to address the latent load and bring in the required refresh air.

Radiant systems work well under most flooring types, including carpet, hardwood, slate, tile, marble, linoleum, bamboo, cork and concrete. A proper system design by a radiant professional will determine the heat output based on the flooring type.

No, a properly designed radiant floor heating system will deliver warmth that brings the greatest human thermal comfort to a space. If a space requires additional heat to satisfy the heat load, the design can incorporate radiant walls and/or ceilings. Uponor offers design support as well as design software to ensure a radiant heating system offers the greatest comfort and efficiency possible.

Because PEX pipe does not corrode, pit, scale or rust, it is highly durable and does not require any maintenance. In general, pumps and boilers may require maintenance depending on the manufacturer. Refer to the pump and boiler manufacturers for maintenance information.

Yes, in fact, separate heating and cooling systems make the most sense. Radiant floor heating keeps the heat near the floor to provide the greatest comfort. Air-conditioning ductwork, on the other hand, is placed only where it is needed to cool the home. The result is optimal comfort and efficiency all year round.

Uponor offers several products that are perfect for basement installations. Fast Trak™ knobbed mats work directly on concrete floors. The mats simply adhere to the concrete and then the PEX pipe snaps into the mats. Fast Trak 0.5 is ideal for retrofits with a low, ½" profile, and Fast Trak 1.3i offers insulation under the panel for added system performance. Uponor also offers Quik Trak® plywood radiant panels that feature a ½" profile perfect for remodeling or retrofit projects. Simply install a plywood subfloor onto the concrete and then fasten the Quik Trak panels to the plywood subfloor.

Absolutely. Uponor radiant floor heating systems are flexible to heat an entire home or just specific rooms. The most common spaces for radiant floor heating in a home include bathrooms and the basement.

Yes, this is a common practice when homeowners want the efficiency and comfort of radiant floor heating in their home eventually, but are not ready to install the complete system during construction. The PEX pipe goes into the slab during construction, and then the homeowners can choose when to complete the system.

A hydronic radiant cooling system is an installation of embedded tubes or surface-mounted panels designed to absorb and remove energy from a space, 50% to 80% of which is radiant energy. Just as in heating, a radiant cooling system uses the structure and surfaces of an area to transfer energy. In radiant heating systems, the energy moves away from the heated surface towards the cooler area. In radiant cooling systems, the energy moves towards the cooled surface from the warmer area.

Yes, there are low-mass radiant cooling systems and high-mass radiant cooling systems. Low-mass radiant cooling systems circulate cool water in specialized panels or beams and typically operate during the occupied time. High-mass systems cool the building structure (slab, walls, ceilings) during unoccupied time and provide the additional advantage of off-peak cooling and further reduction in energy costs.

Because the radiant surface design is typically only 2 to 4 degrees below the desired indoor air temperature, there are many opportunities for innovative cooling sources, such as night fluid cooling, ground-coupled hydronic loops and indirect evaporative cooling.

• Museums
• Institutional and educational facilities
• Office buildings
• Atrium areas
• Manufacturing facilities
• Retail spaces
• Hospitals and Healthcare facilities
• Dormitories, barracks and prisons
• Churches
• Airports

Yes, there are very considerable LEED® advantages with radiant cooling systems. Including, but not limited to, reducing peak loads due to thermal energy storage in the panel structure, exposed walls and partitions. Additionally, radiant cooling systems can use ground and bay water because they operate at a higher supply chilled-water temperature.

The most important factor when designing a radiant cooling system is avoiding condensation on the surface. To accomplish this, the design must incorporate a supply water temperature controlled by the dew point temperature. It is possible to cool with a radiant system, but the design should include a supplemental system to control humidity in the space.

The maximum cooling capacity for most spaces is less than 17 Btu/ft²/h (50W/m²). In spaces with direct sunshine on the floor (atriums, entrance halls, show rooms) the cooling capacity will be significantly higher, around 14 Btu/ft²/h.

Yes, because the floor construction influences the heat transfer between the floor surface and the pipes, the calculation of the cooling capacity can be based on the same method as radiant heating.

Radiant cooling has gained popularity in Europe and North America because it offers the potential to reduce cooling energy consumption and peak cooling loads when coupled with building thermal mass.

No. A phase change is required to address this load. The ventilation system will address the latent load and also control the balance of the sensible load throughout the occupied time of the day.

PEX is an acronym for crosslinked polyethylene. It is a flexible, durable, plastic piping material that has been used in radiant heating applications since the 1970s and plumbing applications since the mid-1990s.

No, PEX falls into three different categories based on its manufacturing method: PEX-a, PEX-b and PEX-c. PEX-a uses the Engel method for 80%+ crosslinked pipe; PEX-b uses the Silane method 65 to 70% crosslinked pipe; and PEX-c uses the radiation method for 70 to 75% crosslinked pipe. Higher crosslinking produces a pipe that is more flexible and more durable with thermal and elastic memory properties.

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, restoring the pipe to its original durability.

Elastic memory references how PEX-a piping will quickly return to its original dimensions after expansion. This allows exceptionally strong ASTM F1960 ProPEX® fitting connections. It also enables Uponor PEX-a pipe to be much more resilient in freeze-thaw conditions.

An ASTM F1960 ProPEX connection is made with an expansion tool and an expansion ring. The installer slides the expansion ring onto the end of the pipe and then expands the pipe and ring with the tool before inserting a fitting. As the pipe and ring shrink over the fitting, it creates a strong connection that holds tight with up to 1,000 pounds of radial force.

Uponor offers Wirsbo hePEX™ oxygen-barrier PEX pipe for hydronic heating and cooling systems.

Wirsbo hePEX is available in pipe sizes up to 4".

Uponor PEX is rated at 200°F (93.3°C) at 80 psi (5.5 bar), 180°F (82.2°C) at 100 psi (6.9 bar) and 73.4°F (23°C) at 160 psi (11 bar). At 200°F at 80 psi, any hydronic application with water temperatures at or below this value is perfectly applicable for the product.

PEX pipe is manufactured to be a copper tube size (CTS) pipe with a wall thickness conforming to a standard dimension ratio of 9 (SDR 9).

Uponor PEX-a pipe does not sweat like copper, due to its very low coefficient of thermal conductivity of 0.219 Btu/(hr•ft²•°F). Copper has a coefficient of thermal conductivity between 300 and 400 Btu/(hr•ft²•°F), depending on wall thickness (type K, L or M). The thicker walls of PEX-a pipe act as an insulator, offering insulation values of approximately R-0.19. The heat transfer from copper is much greater; PEX-a offers up to 30% better insulating value when comparing uninsulated PEX-a with uninsulated copper pipe.

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. To minimize the expansion and contraction in systems with Delta Ts greater than 40°F, clamp the pipe at a maximum of 32 ft. (9.7 m) on center.

PEX absorbs sound in the range of 10 dB/cm; metals, on the other hand, only absorb sound in the range of 0.1-1.0 dB/cm. For a given change in velocity, the intensity of sound from a copper pipe will be at least 8 times higher than that of PEX-a pipe. Furthermore, using PEX-a instead of copper can reduce peak pressures caused by a quick-acting valve by 18 to 40 percent.

Due to its flexibility and expansion characteristics, PEX pipe is much more freeze resistant when compared to copper and CPVC. Because of its shape memory, PEX-a can expand up to three times its diameter, so if water freezes in the pipe, the pipe can flex to accommodate the expansion and then shrink back down after the ice thaws.

Uponor AquaSAFE™ is a fire sprinkler system that uses the same durable, trusted Uponor AquaPEX® pipe and ProPEX® fitting system the building industry has depended on for decades in plumbing systems around the globe. The system is installed per the National Fire Protection Association (NFPA) 13D guidelines for the installation of sprinkler systems in one- and two-family dwellings and manufactured homes. AquaSAFE can be installed as a multipurpose or standalone system, and Uponor offers training for licensed plumbers to install the system.

A multipurpose system combines the fire sprinklers with the home’s cold-water plumbing system. It uses the same Uponor AquaPEX pipe that provides potable water to the plumbing fixtures, so there is always a ready supply of water to the sprinklers if needed in the event of a fire.

Sometimes a standalone fire sprinkler system is better for home. For these instances, Uponor offers innovative design layouts with Uponor AquaPEX pipe that reduces connections by 70% versus traditional rigid piping systems.

ASTM F876 and ASTM F877 manufacturing standards incorporate benchmarks for chlorine resistance to ensure PEX pipe can withstand the potential oxidative effects of heavily chlorinated water. Uponor AquaPEX pipe meets the highest requirement per ASTM F876 and F877 for chlorine resistance at end-use conditions 100 percent of the time at 140°F (60°C).

Because sprinklers protect homes and decrease a city’s necessary firefighting resources, communities often offer construction incentives (trade-ups) to builders and developers, including narrower streets, fire-related code alternatives, additional permitted units, fewer fire hydrants, smaller water mains and more.

Ecoflex® is a flexible, durable, underground pre-insulated pipe system that features PEX service pipes encased in multilayer, closed-cell, polyethylene-foam insulation and covered by a watertight, corrugated HDPE jacket.

The unique properties of Ecoflex make it ideal for commercial and residential applications that require insulated underground piping. The lightweight, flexible, pre-insulated pipes are strong enough to tackle any underground plumbing, heating or cooling application, yet install easily and quickly. The long coil lengths eliminate most buried connections, saving time and money, and the durable PEX pipe and corrugated HDPE jacket make it highly resistant to corrosion.

Ecoflex has many commercial and residential applications — predominantly in heating, cooling and potable-water systems for large-scale complexes such as schools and colleges, resorts and hotels, hospitals and institutions, and housing developments. Radiant heating and cooling as well as snow and ice melting systems can also use Ecoflex as the pipe distribution system of choice. Outdoor furnace and boiler contractors as well as homeowners can depend on Ecoflex for a trouble-free, energy-saving solution to piping underground when the heat source is located away from the structure.

Ecoflex Thermal features Wirsbo hePEX™ pipe that has an oxygen-diffusion barrier to protect ferrous components in hydronic heating and cooling systems. Ecoflex Potable PEX has Uponor AquaPEX® pipe for plumbing applications.

· Thermal Single (Wirsbo hePEX) is available in ¾", 1", 1¼", 1½", 2", 2½", 3", 3½" and 4" pipe sizes.
· Thermal Twin (Wirsbo hePEX) is available in 1", 1¼", 1½", 2" and 2½" pipe sizes.
· Potable PEX Single (Uponor AquaPEX) is available in ¾", 1", 1¼", 1½", 2" and 3" pipe sizes.
· Potable PEX Twin (Uponor AquaPEX) is available in 1", 1¼", 1½" and 2" pipe sizes.
· Potable PEX Plus (Uponor AquaPEX) with heat trace is available in 1¼" pipe size.

Ecoflex products up to 3" use Uponor ProPEX® expansion fittings. For sizes above 3", use compression fittings.

Ecoflex is available in standard factory coil lengths of 1,000 ft. for 1" PEX pipe, 500 ft. for 1¼" PEX pipe and 300 ft. for all other products. Custom coil lengths are available for shorter or longer coils. Contact Uponor Customer Service at 888.594.7726 (U.S.) or 888.994.7726 (Canada) for details.

Yes, Ecoflex Potable PEX Plus comes with a heat trace wire applied on the pipe. The self-regulating heat trace wire has a maximum output of 5W/ft. to keep the water in the pipe from freezing.

With Ecoflex, the layers of foam are not bonded to each other or to the service pipe and jacket, allowing for each layer to move independently (the same relationship as between a steel rod and a braided steel cable — both have similar strength but the cable is much more flexible). Making connections with Ecoflex is also much easier since the insulation is not adhered to the pipe. With bonded systems, manufacturers recommend cutting the jacket, peeling it away from the foam, removing the foam with a chisel or saw and removing the excess foam with sandpaper. Using the sandpaper is a delicate process as it is important not to perforate the oxygen-diffusion barrier on the service pipe.

Yes. With bonded systems, the polyurethane foam is sprayed into the HDPE jacket and hardens. Once the foam hardens, low-conductivity, high-pressure gases exist inside the cells of the foam when compared to atmospheric pressure. Over time, the higher-pressure gases diffuse through the cells outward, escaping the foam. As the pressures inside the cells stabilize, the net conductivity of the remaining gases increase. This diffusion process continues to occur until the pressure inside the cells reach a balance with the surroundings. This process yields acceptable performance for the system initially; however, thermal performance diminishes as time progresses.

Contact Uponor Customer Service at 888.594.7726 (U.S.) or 888.994.7726 (Canada) for assistance with quotes and designs as well as questions regarding the product and solutions.