R32 is the refrigerant in virtually every new air conditioning system installed in the UK today. Whether you’re commissioning a new Daikin, Mitsubishi Electric, Fujitsu or Samsung split system, you’re working with R32. This guide covers everything HVAC engineers need to know — from thermophysical properties to A2L safety, charge weights, and why R32 replaced R410A across the industry.
What Is R32 Refrigerant?
R32 (difluoromethane, HFC-32) is a single-component HFC refrigerant with a Global Warming Potential of 675 — approximately one third of R410A’s GWP of 2,088. It was commercially introduced by Daikin in 2012 and has since become the standard refrigerant for residential and light commercial split AC systems worldwide, including all major UK market products.
Unlike R410A (which is a 50:50 blend of R32 and R125), pure R32 is a single-component refrigerant. This has practical advantages: it cannot fractionate during leak events, and it can be topped up as gas or liquid without composition shift.
R32 Key Technical Properties
| Property | R32 value |
|---|---|
| Chemical formula | CH₂F₂ (difluoromethane) |
| GWP (AR5, 100-year) | 675 |
| ODP | 0 |
| Safety classification | A2L (low toxicity, mildly flammable) |
| Boiling point at 1 bar | −51.7°C |
| Critical temperature | 78.1°C |
| Critical pressure | 57.8 bar |
| Burning velocity | <10 cm/s (mildly flammable threshold) |
| Compressor oil | POE (polyolester) |
Why the Industry Switched from R410A to R32
The shift from R410A to R32 was driven by the UK and EU F-Gas phase-down regulations, which allocate progressively smaller quotas of high-GWP fluorinated gases. R410A (GWP 2,088) consumes approximately three times the quota of R32 (GWP 675) per kilogram. For AC manufacturers producing millions of units annually, this was an existential commercial pressure.
Beyond regulation, R32 offers genuine technical advantages:
- Higher efficiency: R32’s thermophysical properties yield better volumetric efficiency, allowing equivalent cooling capacity with 20–30% less refrigerant charge by weight
- Lower charge weight: A 3.5 kW R32 system requires approximately 600 g of refrigerant vs 800–900 g for an equivalent R410A system, reducing material cost and F-Gas quota consumption
- Single component: Cannot fractionate during leak events; easier to handle and recycle
- Proven performance: Since 2012, billions of R32 system-hours have accumulated globally across all major climate zones
R32 Safety: Understanding the A2L Classification in Practice
R32 is classified A2L — the designation that initially caused hesitation across the HVAC industry. In practice, A2L means:
- “A”: Low acute toxicity — similar to R410A and R32 in terms of human health risk at normal concentrations
- “2”: Flammable — but only weakly so, with a Lower Flammability Limit (LFL) of 14.4% by volume in air
- “L”: Low burning velocity — less than 10 cm/s at 23°C (for reference, natural gas burns at 37 cm/s)
In the UK, A2L refrigerants are governed by BS EN 378 (Refrigerating Systems and Heat Pumps). For engineers transitioning from R410A, the key practical differences are:
- All equipment (compressors, expansion valves, coils) must be A2L-rated and marked accordingly
- Adequate ventilation must be ensured during installation in enclosed spaces
- Some larger systems require refrigerant leak detection under EN 378 Part 1 requirements
- Brazing and welding adjacent to R32 systems requires standard precautions for any flammable atmosphere
Tens of millions of R32 systems are now in operation globally, including in the UK. The A2L risk is well-understood and manageable within normal HVAC practice.
R32 Charge Weights: What to Expect
R32’s higher density and efficiency mean systems require less refrigerant charge than equivalent R410A equipment. Typical guidance (always verify against the manufacturer’s nameplate):
- 2.5 kW split: 400–550 g
- 3.5 kW split: 550–700 g
- 5.0 kW split: 700–900 g
- 7.0 kW split: 800–1,100 g
- Multi-split (3× indoor): 1.2–2.5 kg depending on pipe run and model
A single 9 kg R32 cylinder from Refrigerant Gas Supplies Ltd is typically sufficient for multiple residential system top-ups, or a full charge on mid-range commercial systems.
R32 vs R410A: The Key Differences
For a full head-to-head comparison, see our R32 vs R410A guide. In summary: use R32 for all new UK AC installations; use R410A only for servicing existing R410A systems. Never mix the two.
Buying R32 in the UK
Refrigerant Gas Supplies Ltd, based in Wakefield, Yorkshire, supplies R32 in 9 kg refillable cylinders with 99.9% minimum purity. F-Gas Category I certification is required to purchase. Next-day mainland UK delivery available. Call +44 7988 028925 for trade and bulk pricing.
Frequently Asked Questions
Can I use R410A gauges and tools on an R32 system?
No. R32 operates at higher pressures and requires gauges and tools rated for R32. Use R32-rated or multi-refrigerant tools calibrated specifically for R32 — not R410A-only equipment.
Is R32 safe to use? What does A2L mean?
R32 is classified A2L — mildly flammable with a burning velocity below 10 cm/s. It is safe when handled by trained engineers following EN 378 Part 1 guidelines. Millions of R32 systems operate globally without incident.
How much R32 does a typical UK split AC system need?
Typical 3.5 kW systems need 550–700 g; 7 kW systems need 800–1,100 g. Always follow the manufacturer’s nameplate charge weight. A 9 kg cylinder is sufficient for multiple residential top-ups.
Does R32 require a different compressor oil to R410A?
Both use POE oil, but the specific viscosity grade may differ. Always follow the compressor manufacturer’s oil specification. Never substitute mineral oil in R32 systems.