Flow Environmental Services, St. Paul Local 455 Team Up for CO₂ Heat-Pump Training and Demonstrations

In conjunction with Minnesota’s initiative to develop a clean-energy hub, Rogers, Minnesota (U.S.), manufacturer Flow Environmental Services and the St. Paul Steamfitters/Pipefitters Union (Local 455) have teamed up to deliver hands-on CO₂ (R744) heat-pump training and demonstrations.

Grid Catalyst, a Minneapolis energy technology accelerator and facilitator, coordinated the project, which included public/private funding through the Minnesota Energy Alley initiative. The ANSWR CO₂ heat pump, manufactured and installed by Flow, meets the 100,000ft2 (9,290m2) union facility’s base cooling/heating load through the building’s existing HVAC and hydronic system, Grid Catalyst told NaturalRefrigerants.com. The design also offers versatile training configurations, with connections to geothermal and outdoor air heat sources.

“We’re not only running our own building’s heating and cooling on the ANSWR heat pump, but we’re building a living lab our apprentices can train on every day,” said Jeremy McConkey, Training Director at Local 455.

Grid Catalyst indicated that a third-party measurement and verification study, conducted with engineering and utility partners, will validate the CO₂ heat pump’s performance, with results expected in 2027.

The opportunities: “This site will be open for nationwide training and demonstrations, with a strong emphasis on CO₂ refrigeration for high-, medium- and low-temperature applications,” Grid Catalyst said.

• To support the adoption of the technology, Local 455 maintains an open-door policy, showcasing the CO₂ heat pump to engineers, owners, policymakers, utility providers and the greater community.
• Local 455 provides “cutting-edge” technology training for commercial and industrial refrigeration, geothermal, HVAC, hot-water heating, steam and controls, according to Grid Catalyst. With Flow’s expertise, the manufacturer will work with the union to create a new training program for the CO₂ heat pump.
• “Having this technology installed and operating at the Local 455 training center means the next generation of HVAC technicians will come trained on CO₂ systems,” said Sean Jarvie, Flow Environmental Systems’ CTO. “That’s how you change an industry.”

The benefits: The ANSWR heat pump, capable of simultaneously providing cooling, heating and domestic hot water, replaces traditionally separate systems to cut upfront costs and provide efficiency gains, according to Flow.

• The unit offers several configurations, including air source, water source, geothermal, heat recovery chiller/boiler or a hybrid of all these options.
• The modular unit operates in ambient temperatures ranging from −40 to 120°F (−40 to 49°C), supplying domestic hot water at 180°F (82°C), heating from 90 to 180°F (32 to 82°C) and cooling from 0 to 75°F (−18 to 24°C).
• Through the Local 455 installation, Flow will gather real-world data to confirm that the ANSWR system performs reliably in North America’s coldest climates, with winter temperatures dropping as low as −40°F.

Growing market: Flow expects significant sales growth in 2026, the company told NaturalRefrigerants.com. It added that in January alone, it received more commitments to purchase ANSWR CO₂ heat pumps than in the previous 12 months.

• Flow, along with Ambient Enterprises and Gil-Bar Industries, was named runner-up in New York’s Empire Technology Prize competition for developing, manufacturing and installing high-temperature CO₂-based heat pumps for a range of commercial applications.
• The company reports that in 2025 it opened a decarbonization training center in San Jose, California, and provided CO₂ equipment for multiple applications, including airports, hospitality, multi-family units, offices, universities and more.

Quotable: “The biggest barrier to alternative refrigerant adoption isn’t the technology ‒ it’s the lack of real-world proof points,” said Nina Axelson, President of Grid Catalyst. “That’s exactly what pilot installations like this one create. When a union training center is using a CO₂ heat pump as both a main source of heating and cooling as well as a teaching tool for future installers, you are moving the needle from ’emerging technology’ to ‘industry standard in the making.'”

“This site will be open for nationwide training and demonstrations, with a strong emphasis on CO₂ refrigeration for high-, medium- and low-temperature applications.”

Grid Catalyst