Uponor Solutions:
Residential Radiant Floor Heating

Radiant Floor Heating FAQs for Contractors

How does radiant floor heating work?
How long has Uponor Radiant Floor Heating been around?
What are the main components in a radiant floor heating system?
What is PEX tubing?
What is the difference between PEX-a, PEX-b and PEX-c tubing?
What are the temperature and pressure ratings for Uponor PEX?
What are the Uponor PEX manufacturing standards?
What are the Uponor PEX listings?
What are the Uponor PEX codes?
What installation methods work best for installing radiant floor heating systems?
Where can I buy Uponor products and tools?
Where can I find specifications and submittals?
Does Uponor offer a warranty on its radiant floor heating system?
How do I get trained to install Uponor systems?

In a radiant floor heating system, warm water flows through flexible plastic tubing called PEX that is located underneath or within the floors. (PEX is an acronym for crosslinked polyethylene.) The PEX tubing carries the warm water into specific rooms or “zones” to effectively heat people and objects in every corner of the room.

Uponor (formerly Wirsbo) was the first to bring radiant floor heating to North America more than 40 years ago. And the concept of radiant floor heating has been around since ancient Roman times. Radiant floor heating has been, and continues to be, used in many countries around the globe to effectively bring comfort in even the most extremely cold climates of the world.

The main components in a radiant floor heating system include a heat source, pumps, manifolds, PEX tubing and controls.

PEX is an acronym for crosslinked polyethylene. It is a flexible, durable, corrosion-resistant product that possesses distinctive properties that make it ideal for radiant floor heating and plumbing systems. There are three different types of PEX tubing: PEX-a, PEX-b and PEX-c. Uponor manufactures PEX-a tubing, which is considered the superior type of PEX in the industry.

All three PEX manufacturing processes generate tubing that is crosslinked to varying degrees and are acceptable for potable-water and hydronic radiant floor heating applications.

  • PEX-a is manufactured using the  Engel or peroxide method
  • PEX-b is manufactured using the Silane method
  • PEX-c is manufactured using the E-beam (electron beam) or radiation method

Uponor manufactures PEX-a tubing. The PEX tubing industry considers PEX-a superior because the crosslinking is done during the manufacturing process when polyethylene is in it amorphic state (above the crystalline melting point). Because of this, the degree of crosslinking reaches around 85% (higher than PEX-b or PEX-c), resulting in a more uniform, more flexible product with no weak links in the molecular chain.

Uponor PEX carries the following hydrostatic temperature and pressure ratings.

  • 200°F (93.3°C) at 80 psi
  • 180°F (82.2°C) at 100 psi
  • 120°F (48.9°C) at 130 psi (½" tubing only)
  • 73.4°F (23°C) at 160 psi

In accordance with ASTM F876 Standard Specification for Cross-linked Polyethylene (PEX) Tubing, the excessive temperature and pressure capability for Uponor AquaPEX® is 210°F (99°C) at 150 psi.

Uponor PEX is manufactured to the following standards.

  • ANSI/NSF Standard 14 — Plastics Piping System Components and Related Materials
  • ANSI/NSF Standard 61 — Drinking Water System Components — Health Effects
  • ASTM F876 — Standard Specification for Cross-linked Polyethylene (PEX) Piping
  • ASTM F877 — Standard Specification for Cross-linked Polyethylene (PEX) Plastic Hot and Cold Water Distribution Systems
  • ASTM F1960 — Standard Specifications for Cold Expansion Fittings with PEX Reinforcing Rings for use with Cross-linked Polyethylene (PEX) Piping
  • ASTM F2023 — Standard Test Method for Evaluating the Oxidative Resistance of Crosslinked Polyethylene (PEX) Piping and Systems to Hot Chlorinated Water
  • ASTM F2657 — Standard Test Method for Outdoor Weathering Exposure of Cross-linked Polyethylene (PEX) Piping
  • ASTM E84 — Standard Test Method for Surface Burning Characteristics of Building Materials
  • CAN/ULC-S102.2 — Standard Method of Test for Surface Burning Characteristics of Flooring, Floor Covering and Miscellaneous Materials and Assemblies
  • ASTM E119 — Standard Test Methods for Fire Tests of Building Construction and Materials
  • UL 263 — Standard for Safety for Fire Tests of Building Construction and Materials
  • CAN/ULC-S101 — Standard Methods of Fire Endurance Tests of Building Construction and Materials
  • ASTM E814 — Standard Test Method for Fire Tests of Through-Penetration Fire Stops
  • CAN/ULC-S115 — Standard Method of Fire Tests of Firestop Systems
  • AWWA C904 — Cross-linked Polyethylene (PEX) Pressure Pipe, ½ in. (12 mm) Through 3 in. (76 mm) for Water Service
  • CAN/CSA B137.5 — Cross Linked Polyethylene (PEX) Piping Systems for Pressure Applications
  • CAN/CSA B214 — Installation Code for Hydronic Heating Systems
  • UL 1821 — Standard for Safety for Thermoplastic Sprinkler Pipe and Fittings for Fire Protection Service
  • CAN/ULC/ORD-C199P — Combustible Piping for Sprinkler Systems

Uponor PEX conforms to the following listings. Be sure to visit the listing agency’s website for complete details.

  • cNSFus-rfh
  • cNSFus-pw
  • cNSFus-fs
  • cQAIus
  • UL
  • CSA
  • WH
  • ETL
  • PPI TR-4
  • ICC-ES
  • BMEC
  • CCMC

Uponor PEX meets the following codes:


  • ICC
  • IPC
  • IMC
  • IRC
  • UPC
  • UMC
  • NSPC
  • HUD
  • UFGS
  • NPC of Canada
  • NBC of Canada

It depends on the application. For a concrete floor, it’s best to install the tubing before the concrete is poured. You can tie the tubing to wire mesh or staple it down to foam board and then pour the concrete over the tubing to embed the tubing in the slab. For plywood subfloors, you can use Quik Trak® radiant panels or Fast Trak™ knobbed mats. For joist-heating applications, where the tubing is installed between the joists under the floors, you can use clips to “hang” the tubing or use Joist Trak™ heat-emission plates. To learn more about these products, visit www.uponorpro.com.

Uponor products and tools are sold through our distributor partners. You must be a professional contractor to install Uponor products and systems. To help get you started, visit our Find a Rep page to find the local Uponor manufacturer’s rep in your area.

You can find specifications, submittals and other technical documentation on www.uponorpro.com in the Technical Support section.

Yes. Uponor proudly backs the PEX tubing and ProPEX® fittings in its radiant floor heating systems with a 30-year limited warranty when installed by an Uponor-trained professional.

Whether you need training online, on the jobsite or at the factory, Uponor offers a comprehensive training curriculum for HVAC and plumbing professionals. Uponor Academy offers webinars, field training and classroom training at the Uponor North America headquarters in Apple Valley, Minn. (a suburb of the Twin Cities). To learn about all our training opportunities, visit www.uponorpro.com/training.