A2L refrigerants in VRF systems: what changes for design and safety

The transition to lower GWP refrigerants is also changing the way VRF (Variable Refrigerant Flow) systems are designed and installed . The move from traditionally used refrigerants like R410A to A2L solutions , including R32, not only affects the fluid in the circuit: it introduces new considerations regarding the quantity of refrigerant, room size, leak detection, and system configuration.

This is one of the aspects highlighted by the analysis of the North American market, where designers and installers are revising VRF configurations specifically to meet the A2L safety class . Among the consequences are greater attention to individual zone charging, leak detection systems, shut-off valves, and more coordinated design between system, architecture, and controls.

The topic is particularly relevant in Europe as well. The new F-Gas Regulation is progressively reducing the scope for high-GWP refrigerants, and the European Commission identifies R32, A2L with a GWP of 675, as one of the alternatives currently available in multi-split and VRF systems.

A2L and VRF: refrigerant charge becomes a design parameter

A2L refrigerants are classified as low-flammability fluids , with a limited combustion rate compared to class A3 refrigerants. However, their introduction requires a more careful assessment of the quantity of refrigerant that could be released into an environment in the event of a leak.

In VRF systems this aspect takes on particular importance because a single external unit can be connected, via a network of refrigerant pipes, to numerous internal units distributed throughout the building.

The US analysis highlights how design is becoming increasingly charge-conscious and space-specific: the quantity of refrigerant present in the circuit must be considered in relation to the characteristics of the spaces served, especially when small rooms are present.

This can affect :

• sizing and division of circuits;
• route and length of the pipes;
• total amount of refrigerant;
• organization of zones;
• possible detection of leaks;
• circuit interception strategies.

The consequence is that design must be addressed earlier. Architecture, mechanical systems, electrical systems, and control systems become more interdependent.

The precise requirements regarding maximum load, sensors, ventilation, and mitigation measures naturally depend on the applicable safety standards, the type of system, and site conditions: the US requirements cited by the source should therefore not be automatically transferred to the European market.

Sensors and shut-off valves change leak management

One of the most interesting developments concerns the integration of sensors for refrigerant detection .

In systems designed for this function, the presence of a leak can be quickly identified and used to activate specific safety strategies. The source highlights, for example, configurations in which automatic valves can isolate the affected portion of the circuit, limiting the amount of refrigerant potentially released.

The benefit isn't just safety. Early leak detection can also help:

• limit refrigerant emissions;
• avoid prolonged operation with insufficient charge;
• improve diagnostics;
• reduce the amount of fluid lost;
• limit maintenance interventions.

The transition to A2L can therefore promote greater integration between the refrigeration circuit, sensors and control systems , transforming some mitigation measures into useful tools for the operational management of the system.

Another possible evolution involves dividing systems into smaller circuits . Reducing the amount of refrigerant associated with a single zone can simplify some design considerations and limit the amount of fluid potentially involved in a leak.

At the same time, hybrid configurations or solutions that reduce the direct distribution of refrigerant in occupied spaces, while maintaining the possibility of differentiated regulation of the different zones, are gaining interest.

F-Gas: The future of VRF requires refrigerants with increasingly lower GWP.

In Europe, the transformation of VRF systems must also be read in light of EU Regulation 2024/573 .

For split systems with a capacity greater than 12 kW, a category which includes numerous VRF applications, the European timetable provides:

• from 1 January 2029 , the ban on new systems containing fluorinated gases with a GWP equal to or greater than 750, except for exceptions provided for safety reasons;
• From 1 January 2033 , the threshold will drop to a GWP equal to or greater than 150, again with exceptions related to site safety requirements.

R32, with GWP 675, therefore represents a solution compatible with the 2029 threshold for systems over 12 kW, but does not constitute a definitive solution with respect to the limit foreseen for 2033, except in cases in which the safety derogations provided for by the regulation apply.

This element makes the long-term perspective particularly important in the design and development of new VRF platforms.

The transition isn't simply about switching from R410A to R32. The industry will gradually have to adapt to refrigerants and architectures capable of meeting even more stringent GWP thresholds.

For designers, installers, and maintenance technicians, this means preparing for a market in which refrigerant choice, charge quantity, environmental safety, and circuit configuration will be increasingly closely linked.

VRF retains the characteristics that have favored its diffusion in commercial buildings—zonal regulation, modularity, and the possibility of heat recovery—but the A2L transition requires a higher level of coordination right from the early stages of the project.

The real evolution may therefore not only lie in the refrigerant used, but in the very way in which direct expansion systems are designed, monitored and divided within buildings.