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What consultants and specifi ers need to consider when choosing refrigerant
Refrigerant selection is no longer simply a question of technical performance. Environmental impact, fl ammability, building use, installation location, regulatory requirements and future availability all need to be considered at the design stage, as Steve McConnell, director, ICOM, explains
T
he refrigerant landscape is changing rapidly. With tightening F-gas requirements and increasing scrutiny around PFAS, consultants
and specifi ers have an increasingly important role to play in selecting refrigerants that are not only suitable for today’s HVAC and refrigeration applications but remain viable over the lifetime of the system. For heat pump applications, R32 and R290
(propane) are two refrigerants that are commonly used by manufacturers. They illustrate the diff erent considerations that specifi ers need to balance.
Look beyond GWP
Global Warming Potential (GWP) remains an important consideration. R290 has an exceptionally low GWP of 0.02, compared with approximately 675 for R32, based on the latest IPCC assessment values referenced in ICOM’s recently updated guide ‘Flammable Refrigerants within heat pumps - Selection & design considerations’. R290 is also a natural hydrocarbon, with zero ozone depletion potential. However, GWP should not be considered in isolation. A refrigerant’s classifi cation, charge, operating temperatures and the characteristics of the proposed installation are equally important. R32 is classifi ed A2L, meaning it has low toxicity and mild fl ammability. It is widely used in heat pumps and air conditioning and can provide fl ow temperatures of up to around 65°C, depending on ambient conditions and system design. R290 is classifi ed A3 and is highly fl ammable.
Its very low GWP and potential for higher fl ow temperatures – up to around 75°C, subject to ambient conditions – make it an attractive option, but its fl ammability introduces additional design and installation requirements.
Location is a design consideration
For specifi ers, particularly where R290 is concerned, the location of the equipment needs to be considered at the earliest stage rather than left to the installer. R290 is heavier than air and, in the event of a
leak, can accumulate at low points. The heat pump must be a suffi cient distance from openable doors, windows and air bricks to prevent gas from entering the building. Similarly, the unit must be located away from drains, wells, or other low points where gas could accumulate. In addition, poor airfl ow will
8 October 2026 The implication for consultants is clear: the
refrigerant cannot be separated from the building, the installation environment or the wider system design.
Consider the whole system
The specifi cation should also consider practical issues such as available space, airfl ow, noise, condensate management, frost protection and the additional components required by the heating system. For example, minimum water content is important
to avoid excessive cycling of a heat pump, which can reduce effi ciency and increase component wear. Buff er vessels and domestic hot water storage may also be required, creating further space and pipework considerations. With R290 systems, additional safety measures
may include leak detection, automatic shut-off and appropriate protection against refrigerant entering the hydraulic circuit following a heat exchanger failure. A degasser or venting valve should be fi tted on the fl ow pipe, positioned close to the appliance and within the protective zone.
cause the unit to run less effi ciently and can prevent the safe dispersal of refrigerant in case of a leak, so should be installed in a location with natural ventilation and free air movement. Our guide states that exclusion zones can
typically extend around 2 – 4 metres from the appliance, although the manufacturer will defi ne protective or exclusion zones around their equipment, which must be followed. These areas need to be kept clear of potential ignition sources, such as electrical switches, outdoor sockets and gas meters.
Regulations must form part of the specifi cation
Regulatory requirements are another reason that the refrigerant choice should be considered as part of the overall system design. R32 remains subject to the F-gas phase-down, while R290 is exempt from the F-gas phase-down but is subject to requirements associated with its fl ammability, including ATEX and the UK’s Dangerous Substances and Explosive Atmospheres Regulations (DSEAR). Relevant standards include BS EN 378, ISO 5149 and,
where applicable, the requirements of ATEX/DSEAR and national building, fi re and electrical regulations. BS 7671 and BS EN 12828 also need to be considered.
Specify for the future, not just today
Perhaps the most important consideration is longevity. A system specifi ed today needs to remain compliant, serviceable and reliable throughout its expected operating life. Consultants and specifi ers should therefore assess the current and anticipated regulatory framework, consider the building type and occupancy, evaluate system capacity and operating temperatures, and understand the manufacturer’s requirements before selecting a refrigerant. The shift towards lower-GWP and natural
refrigerants will continue to infl uence HVAC and refrigeration design. Making the right choice means balancing environmental performance with safety, compliance, system performance and the realities of the installation. In other words, refrigerant selection should be
treated as a fundamental part of system design – not an afterthought once the equipment has already been chosen.
The ICOM guide ‘Flammable Refrigerants within heat pumps - Selection & design considerations’ can be found here:
https://www.icom.org.uk/media/7e 45efe61305f7baab7dca87e6112cd0/260810-ICOM- Flammable-Refrigerants-Guide-Aug-26.pdf
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