R32 scroll chiller

Lower-GWP alternatives to refrigerant R410a for air-cooled chillers

Customers are increasingly moving towards air conditioning and refrigeration equipment running on lower-GWP alternatives than currently widely used refrigerant R410a.

The current restrictions, such as Europe’s F-Gas regulations, have started the phase-down of HFCs, including R410a, to slow global warming and reduce direct carbon emissions. With the start of HFCs phase-down, prices and availability of these refrigerants were significantly affected and led to a growing demand for lower-GWP alternatives.

Replacements for R410a, such as R32, R452b, and R454b are all flammable refrigerants, classified as A2L (mildly flammable) by ASHRAE. While all of the numerous lower-GWP alternatives are flammable, there are significant differences in their safety classifications and parameters of flammability. These differences affect how these refrigerants can be applied and used safely.

In general, flammability leads to restrictions of maximum charge and where these lower-GWP systems can be installed. With regard to chillers, alternative refrigerants are first applied for air-cooled models intended for outdoor installation, with necessary components replacement and performance optimization.

The best lower-GWP refrigerant option varies by application. For small-to-medium chillers, e.g., scroll chillers, the foremost ones are R32, R452b, and R454b. Each of these refrigerants has specific advantages, disadvantages, and features, based on which the HVAC plant owner can select the most feasible solution.

Refrigerant R32 vs. R410a

R32 is a relatively inexpensive, single-component refrigerant, meaning it is easier to recycle. Chillers with refrigerant R32 deliver about 5-8% higher capacity compared to R410a. With the optimization of system design and components, R32-running chillers also exhibit some efficiency gains. However, owing to high gas discharge temperatures, the operating envelope of R32 chillers is limited. For operation under extremely high ambient temperature conditions (>45°C), the better options are R452b or R454b.

Measured at AR5, R32’s GWP is 675.

Refrigerant R452b vs. R410a

In terms of capacity and efficiency, R452b – an R32/HFO mixture – is the closest drop-in substitute for R410a. It provides a wide operating envelope and excellent performance under high ambient conditions for air-cooled chillers. At the same time, numerous studies and leak incident simulations demonstrate that leaked R452b hardly reaches the flammability limit.

Refrigerant R454b vs. R410a

A mixture of R32 and R1234yf, refrigerant R454b delivers about 3% less capacity but has the benefit of GWP value as low as 467, making it potentially a longer-term solution.






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With its latest air-cooled chiller family, Lightstream Scroll II, Kaltra offers all of the above refrigerants giving the customers more flexibility. For mild climate, we offer models running on R32, while R452b-based units are best suitable for hot climate. For customers focused on maximum environmental sustainability and reduced carbon footprint, refrigerant R454b is the optimum solution.

All models incorporate multiple scroll compressor technology, microchannel condenser coils, gaining the maximum efficiency over rivals, and equipped with refrigerant leak detectors as standard.


Even though refrigerant R410a does not contribute to the depletion of the ozone layer, it has a global warming potential of as high as 2088, so its impact on global warming is considerable. For this reason, water chillers running on lower-GWP alternatives are a good choice in the long term, including systems with 2030-ready refrigerant R454b featuring a GWP value lower than 500.