Heat Pump Refrigerant Types Explained UK 2026

GWP (Global Warming Potential) measures how many times more warming a gas causes per unit mass vs CO2 over 100 years.

• CO2: GWP = 1 (the baseline).
• R290 (propane): GWP = 3 - effectively zero impact.
• R454B (blend): GWP = 466 - moderate impact.
• R32: GWP = 675 - significant per-leak impact.
• R410A (older): GWP = 2,088 - high impact; largely phased out in residential heat pumps.
• R134a (older): GWP = 1,430 - largely phased out.

UK + EU F-gas regulations drive progressive phasedown of high-GWP refrigerants. Lower GWP refrigerants = lower environmental risk if leak occurs + future-proof against phasedown rules.

R290 (propane) is the modern low-GWP standard for new UK residential heat pump installs since 2023.

Where used:

• Vaillant aroTHERM Plus (5, 7, 10, 12 kW residential).
• Octopus Cosy 6.
• Daikin Altherma R (where R290 variant available).
• Mitsubishi Ecodan R290.
• Hitachi Yutaki S Combi R290.

Advantages:

• GWP 3 - effectively zero environmental impact.
• Excellent thermodynamic properties = highest SCOP potential (typically 0.2-0.4 points higher than R32 equivalent).
• Future-proof against F-gas phasedown rules.
• Lower refrigerant cost per kg (propane is industrial commodity).

Considerations:

• Mildly flammable (A3 safety class). Mitigations: outdoor unit only, minimum room volumes if any indoor refrigerant pipework, leak detection systems for indoor concentration thresholds.
• Most residential UK installs use outdoor monoblock design = no indoor refrigerant; mildly flammable rating doesn't affect typical install.
• Some indoor split designs need additional safety provisions.

R32 dominated UK heat pump installs from 2015-2024 - well-established, widely supported, decent properties.

Where used (legacy + new):

• Original Vaillant aroTHERM (pre-2023 Plus variant).
• Daikin Altherma 3 standard.
• Mitsubishi Ecodan PUZ series.
• Many other established residential models.
• Still installed in some retrofit / replacement scenarios where R290 not yet available in the specific size + configuration needed.

Advantages:

• Mature technology + extensive installer experience.
• Lower install complexity vs R290 (similar A2L safety class, established procedures).
• Slightly lower install cost per kW (some manufacturers still price R290 variants at premium).

Considerations:

• GWP 675 - moderate environmental impact per leak.
• F-gas phasedown reducing R32 supply through 2026-2030. Service availability through reclaim guaranteed past 2030.
• Some industry uncertainty on whether R32 will phase down faster than scheduled if regulatory pressure builds.
• Slightly lower efficiency potential vs R290 (-0.2-0.4 SCOP points typical).

R454B is a refrigerant blend designed as a lower-GWP alternative to R410A in commercial chillers + some larger heat pumps.

Where used:

• Commercial / industrial heat pumps (50+ kW).
• Some hybrid systems (heat pump + gas boiler combination units).
• Specialist applications where R290 install constraints make it impractical.

Advantages:

• Lower GWP than R32 (466 vs 675).
• Direct drop-in compatibility with some R410A equipment.
• Established commercial service network.

Considerations:

• Higher GWP than R290 - not future-proof against further phasedown.
• Rarely encountered in UK residential heat pump installs.
• Mainly relevant to commercial property owners + contractors.

UK F-gas regulations (retained EU rules post-Brexit) implement progressive phasedown of higher-GWP refrigerants:

• 2025: R410A largely phased out of new installs (manufacturers no longer producing R410A units for UK market). Service supply increasingly reliant on reclaim.
• 2026: R32 supply reducing; some manufacturers transitioning entire residential range to R290.
• 2027: R32 supply cut further; manufacturers pricing R32 variants at premium vs R290.
• 2030: R32 not phased out completely but supply primarily via reclaim / recycle.
• 2035+: Long-term direction toward A2L + A3 low-GWP refrigerants (R290, R744 CO2, others).

What this means for existing installs:

• Service availability for R32 + R454B units guaranteed through 2030+ via reclaim.
• Cost of refrigerant recharge gradually rising as supply tightens.
• No need to proactively replace working R32 unit for environmental reasons - GWP benefit doesn't justify install cost.
• End-of-life replacement (year 12-18 typical) is the natural transition point to R290.

1. New UK residential install: R290. Lowest GWP, highest efficiency, future-proof. Available in all common UK residential sizes (5, 7, 10, 12 kW).
2. Replacement install (existing R32 unit failed): R290 if available + compatible; R32 acceptable if R290 variant not available in needed size + configuration. Don't replace working R32 unit purely for GWP reasons.
3. Commercial / larger heat pump (50+ kW): R454B or R290 based on availability + install constraints. Commercial route typically follows specialist commercial engineer recommendations.
4. Hybrid system (heat pump + gas boiler): often R32 or R454B based on combined unit availability. Choose based on overall system match.

For typical UK households making a new install decision in 2026, R290 is the right answer.