PEX Tubing

PEX (Poly Ethylene X-Linked) Tubing is a flexible material that has revolutionized the heating industry. With PEX Tubing, radiant heat can be installed in virtually any home to provide the comfort of warm floors. PEX Pipe (or PEX Tubing) for radiant heat is flexible enough to create loops in your floors with minimal connections, durable enough to last for the lifetime of your home, and affordable enough to install today!

• Which type of PEX tubing is best for a standard radiant heat job?

  If by standard you mean a closed system, with cast iron pumps, valves and a boiler, then oxygen barrier PEX is the right tubing for you. Brands of oxygen barrier PEX include hePEX, ThermaPEX, HydroPEX, and Viega PEX.

• Which brand of PEX Tubing is the best?

  Wirsbo hePEX and ThermaPEX tubing are both PEX-a products. PEX-a uses is made using the best manufacturing process (the Engel method) and produces the strongest, most flexible tubing. PEX-a tubing is also the only tubing that can be used with expander style fittings. hePEX is more expensive than ThermaPEX because it is made by Wirsbo (Uponor), the leading brand name, who have been the world leader in PEX for decades. The other brands of PEX, HydroPEX and Viega PEX, are comparable and can be used in standard radiant applications. All of these brands carry at least a 20 year warranty.

• What installation methods are available for PEX?

  There are many different ways to install PEX tubing in a radiant heat system. The most popular are in a slab, in joist bays with aluminum panels or PEX clips, or in a Quik Trak above subfloor system. The most efficient and least expensive way to install PEX is an in-slab application; but unfortunately this option is not always available.

• Which size of PEX is most commonly used for radiant heat?

  1/2" is by far the most common size of tubing used in radiant heat. 5/8", 3/8", and 3/4" follow behind. The size of PEX tubing used does not change the amount of heat that is produced, but it does change the maximum loop length that can be run.

• How far apart should I space the PEX tubing for my radiant job?

  The spacing of PEX tubing in a radiant heat system determines how much heat a given area will produce. This spacing or distance between two PEX lines is also referred to as the on-center distance. The closer that tubing is spaced, the higher the BTU output will be, given that water temperature is held constant. When laying out your tubing you must keep this in mind. For basements and shops, 12" spacing will work. For living areas, tubing can be spaced roughly 9" apart. For a bathroom, tubing can be 6-7" apart. This spacing assumes a moderate climate; if you are located in a warm climate tubing can be spaced farther apart and if you are located in an extremely cold climate tubing should be spaced closer together. Along exposed walls, tubing should be spaced 6" apart for the first 2-3' to combat the heat loss.

• Which tubing is best to use for hydronic heating applications such as baseboard?

  For baseboard and other hydronic heating applications you will want to use either oxygen barrier PEX or PEX-AL-PEX tubing (the aluminum core acts an oxygen barrier). In most applications oxygen barrier PEX (such as ThermaPEX or hePEX) will be used. However, PEX-AL-PEX, because of its ability to hold its shape, is often used. Both of these products are able to withstand temperatures up to 200° F. The oxygen barrier will prevent rusting of cast iron components in your system.

• What is PEX-AL-PEX Tubing used for?

  PEX-AL-PEX tubing is used in some slab applications, Warmboard applications, and in some hydronic heating jobs. The main advantage of using PEX-AL-PEX is its ability to hold its shape when bent or pushed a certain way. This can be great in tight situations such as in the boiler room and for baseboard. However, for in slab and joist applications this tubing can be difficult to work with. PEX-AL-PEX can is great for high temperature systems as well because it has a very low expansion rate of .156" per 100 feet for a 10° temperature rise.

• Can PEX Tubing be used for a solar system?

  No, you cannot use PEX on a solar system because the water temperatures in a solar system can reach 325°, which is too high for PEX.

Try using our Radiant Heat Calculator to find out what materials you need for your job.