Ensuring The Quality Of Radiant Tubing: NSF/ANSI Standard 14
In recent years, consumer interest in radiant floor heating has increased significantly, sparking a wide variety of radiant floor heating products on the market. Plumbing and mechanical codes require these products be certified and labeled by a third-party listing agency.
To that end, NSF International offers a specialized listing program for plastic piping systems and components used in radiant heating applications that goes beyond the requirements of the mechanical code.
NSF/ANSI Standard 14 – Plastic Piping System Components and Related Materials establishes the minimum physical, performance and health effect requirements for plastic piping system components and related materials. This includes plastic and metal fittings, valves and manifolds used with plastic or composite piping systems.
While NSF/ANSI Standard 14 has been in existence for more than 40 years, the adaptation specific to radiant heating products is a fairly recent addition to the standard. Evaluation and NSF certification of radiant heating products require the following steps, as listed below:
Product TestingAll radiant heating pipe and fittings are design-rated for a minimum of 100 psi working pressure at 180 degrees F. Specific testing varies by material type, but always includes:
- Critical dimensions.
- Material-specific physical properties.
- Hydrostatic burst (at multiple temperatures).
- Hydrostatic sustained pressure (1,000 hours at 1.5 times rated pressure at multiple temperatures).
- Excessive temperature (210 degrees F at 150 psi for 30 days).
- Thermocycling (1,000 cycles alternating between 180 degrees F at 100 psi and 60 degrees F at 100 psi).
Long-Term Strength RequirementsNSF/ANSI Standard 14 requires plastic pressure pipe materials to meet long-term strength requirements such as compliance with the Plastic Pipe Institute TR-3. The institute establishes minimum requirements to evaluate the long-term strength of plastic materials. Pipe and pipe material must demonstrate a minimum of a 50-year strength value based on rated temperature and pressure when tested to in accordance with ASTM D2837 or ISO 9080 standards.
Quality ControlNSF/ANSI Standard 14 requires manufacturers to perform critical quality control testing at the production facility at specified frequencies. For example, PEX tubing manufacturers must perform dimensions on tubing at a minimum of every two hours, burst pressure testing every 24 hours, and degree of crosslinking weekly, etc. This minimum quality control testing helps to ensure consistent quality for the plastics industry.
InspectionsNSF requires a minimum of three annual unannounced inspections for radiant heating products. The inspections include verification of the manufacturing processes, material formulation batch sheets, raw material suppliers, frequency and observation of quality control testing, sampling of products for monitoring testing and ensuring production is within the requirements of standards for which NSF has certified.
Products that meet all applicable performance standards for a pressure rated in-floor heating application as required by NSF/ANSI Standard 14 are labeled “NSF-rfh.”
While not required for radiant heating products, many manufacturers design their products for dual-use in potable water applications. Products used in potable water applications are evaluated to NSF/ANSI Standard 61 - Drinking Water System Components - Health Effects. This standard helps ensure that drinking water system components do not leach harmful levels of contaminants into the drinking water. Products meeting this, along with the NSF Standard 14 performance requirements, are marked “NSF-pw.”
In June 2001, NSF listed the first NSF-rfh products. Now, five years later, NSF lists 35 manufacturers including 465 products. These products currently include:
- PEX tubing.
- Composite or multilayer tubing.
- PE-RT tubing.
- Fittings, manifold and valves for use in PEX tubing systems (metal and plastic).
- Materials for use in applicable tubing.