Nebraska-based Centennial Plastics has the distinction of earning the first certification under the new NSF/ANSI 358-1 standard for its geothermal products. The standard, which has been in development for a few years, sets safety and performance baselines for water-based ground source heat pump systems.

The standard rolled out early this year, and I think it injects another level of legitimacy and ease-of-mind to the residential and commercial HVAC market. Kudos to Centennial for leading the way.

Every market wants legitimacy

Even with a raft of state incentives, geothermal lags other low-carbon technologies. The buy-in for geothermal in the United States sits in the low single digits. That’s a shame. Yes, it’s expensive up front. But, as any drillers in the industry will tell you, it’s a long-term investment that pays off.

Having a standard for water-based HVAC systems doesn’t fix the affordability problem. It is, however, a nice reply for contractors to have when questions arise from potential customers about this strange, “new” technology. I think a lot of consumers have misconceptions about geothermal and distrust of technology unfamiliar to them. Many of those same consumers know NSF International—or at least recognize the logo. They see it on products from coffee makers to faucets. It’s familiar and trusted. Geothermal products can benefit from that trust. As a consumer, I take comfort in knowing a third party has reviewed a product and found it safe and that it performs as designed and expected.

This standard brings the industry a step closer to consistency, so that loops installed in Arizona perform the same as loops installed in New York. That consistency cannot be undervalued when it comes to making a case to the public for geothermal.

More about NSF/ANSI 358-1

The NSF/ANSI 358-1 standard sets down minimum physical and performance requirements for piping and other system components. NSF International developed it with input from engineers, piping manufacturers, regulators and others. The standard includes requirements from the American Society for Testing and Materials, the Canadian Standards Association and the American Water Works Association.

Each of these groups tried to answer the question: What characteristics are key to ensure water-based ground source heat pump systems perform as expected once installed? Together, they identified minimum requirements for long-term durability, chemical resistance and quality control during manufacturing.

What this means to Centennial, the industry

“Our CenFuse geothermal pipe certification to NSF/ANSI Standard 358-1, which includes both the pipe and the fittings, provides engineers, distributors and contractors assurance that not only the pipe but the entire ground loop heat exchanger, meets the safety and quality levels their customers demand,” said David Schnase, Centennial’s vice president of sales and marketing. “Centennial is also the first manufacturer to earn the NSF certification to NSF/ANSI Standard 358-1. Our leadership and commitment to the geothermal industry continues to be at the forefront of our product offerings.”

Centennial has every right to crow about its achievement. Their products and facilities survived a range of evaluations and the result is a product contractors and consumers can rely on.

“This new NSF American National Standard provides a credible, science-based foundation that will help grow the geothermal pipe industry by helping these products gain acceptance and use by contractors, engineers and regulators,” said Shannon Murphy, general manager of NSF International’s Plumbing Programs. “Manufacturers such as Centennial Plastics that earn certification to NSF/ANSI Standard 358 will help increase confidence and product acceptance by ensuring geothermal pipe complies with all of the standard’s requirements.”

How other manufacturers get certified

To secure NSF/ANSI 358-1 certification, manufacturers of polyethylene pipe and fittings undergo audits of their raw materials, manufacturing process, quality control and product marking. Centennial’s CenFuse geothermal pips also earned certification to NSF/ANSI Standard 14: Plastic Piping System Components and Related Materials, as a prerequisite to the NSF/ANSI 358-1 certification.

Manufacturers interested in pursuing certification should visit NSF’s water programs website. U.S. manufacturers can also email

NSF International writes standards for, tests and certifies a range of products from plumbing to food safety. It was founded in 1944, operates in more than 150 countries and is accredited by the American National Standards Institute.