Third-party program ensures product quality and safety for pipes and fittings used in these systems.



Since long before the Roman Empire, people have used the earth’s natural heat for their benefit. Long after the Roman Empire fell, in 1904, a prince in Italy tested the world’s first geothermal generator. Today, more than 100 years after the initial start up, the generator is still in use. Since that first test more than a century ago, geothermal power, heating, and cooling systems have become more and more widespread across the world. The spread of geothermal systems started very slowly, but in the past few decades their use has skyrocketed.

According to the Geothermal Energy Association, the use of geothermal heat pumps has been increasing at a rate of 15% every year. The GEA estimated that there were more than 600,000 units in 2005 with 50,000 to 60,000 heat pumps added every year. With energy costs seemingly ever on the rise in today’s world, it is no surprise that both people and businesses are turning more and more toward geothermal heating and cooling – a system that has been estimated to save consumers up to 50% on heating and cooling (according to the EPA).

As a green source of energy, geothermal systems have been shown to be both cost efficient and plentiful. Geothermal systems utilize the earth’s natural steady temperature to heat in the cold months and cool in the hot months. Simply put, a geothermal system consists of pipe placed deep in the ground where the water is pumped in order to absorb the temperature of the earth and then pumped back into the building for heating or cooling. These systems have shown the potential to end up ‘paying for themselves’ within a short time, typically 3 – 5 years. The economic advantages of geothermal systems are enormous, especially in large applications such as shopping malls, hospitals or schools.

The green benefits and long-term cost effectiveness of a geothermal system has elevated the system’s popularity into the public eyesight. Yet how can a consumer or inspector know the system (typically polyethylene [PE] pipe and fittings) is safe? Providing reliable heat and cooling to homes or businesses is critical. Homes,  hospitals or schools that have lost heat in the cold winter months or cooling during the heat waves of summer can experience disastrous and costly results.

So what are the requirements for geothermal piping? NSF Intl. has developed a third-party certification program for the testing and listing of geothermal piping. These PE pipe and fittings are more commonly seen and used in potable water systems. Certifiers have taken the requirements of these products used in potable water pressure applications and used them as the basis for certification or authorization for use in geothermal applications. These requirements include:
  • Certification to NSF/ANSI Standard 14;

  • PPI Statement Q for PE pipe;

  • Compliance with a current performance standard as identified in Section 2 of NSF/ANSI Standard 14 (plastic piping system components and related materials)

  • Pipe material having a minimum 50-year strength at a rated temperature and pressure based on hydrostatic design basis (HDB) or minimum required strength (MRS);

  • Compliance with Section 4 of NSF/ANSI Standard 61 (Drinking Water System Components – Health Effects) for products that are used in potable water systems as required by the performance standard.

    Manufacturers who comply with these requirements have available to them the legitimate marking of this information. This becomes very important when the identification marking (such as the print strip on a pipe) may vary depending on the manufacturer, especially when the product is not certified to a standard that specifies marking requirements. However, a product that has been certified will be identified with the appropriate certification mark of the agency; for example: NSF – geothermal, along with but not limited to, material specification, performance standard, whether or not the product is authorized for use in potable water systems, and the pressure rating of the pipe.

    NSF has also developed a certification program for products sold in Canada, which includes:
  • Pipe material having a minimum 50-year strength at rated temperature and pressure based on hydrostatic design basis (HDB) or minimum required strength (MRS) compliance with CSA B137.1.

  • Compliance with CSA C448.

  • Physical properties of the material must meet a minimum cell classification of 345564 or 345434 when tested in accordance with ASTM D3350.

  • The material must be PE 3408 or greater.

    The certification of these products adds two further items to give reassurance in the quality of the products: auditing of the facility and quality control testing.


    • Quality Control Requirements for PE Pipe

    Standard 14 identifies specific testing requirements for manufacturers to perform critical quality control testing at the products facility at specified frequencies. This is in addition to quality control requirements established by the product design standards. The following table is an example of requirements for PE pipe:

    Monitoring testing

    A requirement of continued certification is annual inspections and testing. During the facility inspections (where it is ensured the correct formulation is used in the production of geothermal products), samples are collected by NSF from production or from inventory for annual testing. NSF provides a detailed report that summarizes the results of the product testing. Monitoring testing combined with unannounced facility inspections and required quality control testing document continued product compliance.

    New technologies applied to the very old ideas of using the Earth’s natural warmth ensures that geothermal will be a viable source of energy long into the future. Setting and following requirements on these products will, likewise, ensure continued confidence in the quality of the products and create a high level of confidence in their dependability.