AIR HANDLING UNITS
Designing safely with flammable refrigerants
As forthcoming F-Gas changes place greater focus on self-contained air-conditioning equipment and heat pumps, designing with flammable refrigerants is becoming an increasingly important consideration. Jan Magnusson, cooling manager at AHU manufacturer IV Produkt, explains the engineering, testing and rigorous approach to safety behind the development of the ThermoCooler HP R290
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ore than 50,000 hours of design and development, over 45,000 hours of test operation and the examination of well over 1,000 individual risk points. This was the exacting journey required before IV Produkt could introduce an R290 version of the ThermoCooler HP integrated reversible heat pump module to its Envistar Flex air handling unit (AHU) series. Those figures provide some indication of what designing HVAC equipment for a flammable refrigerant really involves. It is not a matter of replacing one refrigerant with another and making a few minor component changes. It requires a fundamentally different approach to product design, risk assessment, manufacturing, testing, controls, installation and ongoing operation. R290, or propane, has an exceptionally low global
warming potential of 0.02, making it an attractive option as the HVAC industry moves towards natural and lower-GWP refrigerants. However, R290 is also classified as an A3 refrigerant, meaning its flammability must be considered throughout the complete design and application process, to ensure a safe operation. Flammable refrigerants should not be treated as something to fear, but neither should they be approached with complacency. Their safe use depends on design confidence rather than guesswork, and with hermetically sealed systems leakages is exceptionally rare. This principle has guided the development of the latest generation of ThermoCooler HP. Designing a version capable of operating with R290 and suitable for both indoor and outdoor applications has required close cooperation across our engineering, manufacturing and testing teams, as well as with specialist consultants and suppliers throughout the refrigeration and component supply chain. Components, electrical equipment, controls and
safety functions cannot be developed in isolation. They must be selected, classified and tested as parts of a complete system.
Regulation driving development
The forthcoming F-Gas changes have been a major driver behind this work. From 2027, scheduled changes will affect relevant units below 50kW, followed by units above 50kW from 2030. Although those dates may appear some distance
24 September 2026
Left: Jan Magnusson, cooling manager at AHU
Below: The new Thermo- Cooler HP R290, part of IV Produkt’s Envistar Flex range, shown along- side an example of an IV Produkt AHU integrated heat pump installed and commissioned in 1980
www.heatingandventilating.net More than 1,000 identified points
When developing ThermoCooler HP for R290, we applied a detailed risk-identification and mitigation process involving a Hazard and Operability Study, or HAZOP, together with Bow-Tie risk and safety analysis. The process resulted in well over 1,000 individual
points requiring investigation, evaluation or mitigation. These points extended far beyond the refrigeration circuit. They included potential ignition sources, material and component classifications, electrical equipment, airflow routes, maintenance access, control responses, abnormal operating conditions and the management of a potential refrigerant leak. The work also had to consider every stage of the
product’s life: initial system design, manufacturing, factory testing, transport, installation, commissioning, normal operation, maintenance and eventual decommissioning. Standards including IEC 60335-2-40 and EN
378 have been applied and provide an important framework for this process. IEC 60335-2-40 addresses product safety
requirements for heat pumps and air-conditioning equipment. EN 378 brings in the wider refrigeration system and its relationship with the building, including refrigerant charge, equipment location, occupancy, ventilation, leak management and maintenance. Together, they reinforce an important point: safe
application does not depend on one component or one protective device. It comes from multiple layers of protection, supported by documented design, manufacturing, testing, installation and operational procedures.
away in the context of an individual construction project, they are very close in design and product- development terms. Commercial HVAC equipment is expected to
remain in operation for many years. At the same time, developing, testing, manufacturing and CE marking a new generation of equipment is a multi-year process. Manufacturers cannot wait until new restrictions take effect before beginning development. Consultants, contractors and property owners must
also consider whether equipment specified today will remain suitable and supportable throughout its expected operational life. Refrigerant selection has therefore become part of a wider discussion involving future compliance, availability, energy performance and long-term building strategy. At IV Produkt, we believe new regulation should be met with new innovation. That is how our industry can remain competitive while ensuring that technical and environmental performance advance together. The new generation of ThermoCooler HP has been developed around our new Multiref DX-concept, allowing the refrigeration cycle to operate with either R290 or R454C. This flexibility gives designers and building owners a choice between two different F-Gas 2027-compliant refrigerants. Either a fully natural A3 refrigerant with an ultra-low GWP, or another low-GWP A2L alternative, depending on the project conditions. Providing that choice, however, involves much more than refrigerant compatibility.
Detect, dilute and evacuate
One of the most important outcomes of the development process is IV Produkt’s new patent- pending Evacuation Dilution Function (EDF). EDF has been developed around three integrated stages: detect, dilute and evacuate. The first stage is detection. Calibration-free
refrigerant detectors continuously monitor the relevant areas of the unit and provide an early warning if a refrigerant leak occurs. If R290 is detected, the system moves immediately into the dilution stage. The building side is sealed off, dedicated evacuation dampers are opened, and a controlled airflow dilutes the refrigerant concentration to a non-hazardous level. The third stage is evacuation. The diluted and non-hazardous refrigerant is removed through the exhaust-air route rather than being allowed to accumulate within the air-handling unit or surrounding plant area. The EDF sequence overrides normal building- management and operational schedules. This is essential because a leak could occur when the unit would ordinarily be inactive, such as overnight. The safety function must therefore remain available regardless of the normal operating timetable. The integrated control system also performs automatic periodic testing of the evacuation function. A safety system is only valuable if it remains ready to operate when required, so self-testing forms an
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