A refrigerant is the working fluid of a heat pump: it absorbs heat by evaporating at low pressure outdoors and releases it by condensing at high pressure indoors. Refrigerants are identified by R-numbers (R290, R32, R410A), a safety class from A1 to A3, and a GWP value. The EU is phasing down high-GWP HFCs — the 2025–2026 quota of 42.9 Mt CO2e sits about 48% below the 2023 level.
What does a refrigerant do in a heat pump?
The refrigerant is the fluid that physically carries heat through the circuit by changing phase. At low pressure in the evaporator it boils well below outdoor temperature, absorbing heat from the air; the compressor raises its pressure so that it condenses above heating-water temperature indoors, releasing that heat. The expansion valve drops the pressure again and the loop repeats.
A refrigerant's boiling behaviour, critical temperature and volumetric capacity decide what a heat pump can do: how cold a climate it tolerates, how hot its water can get, and how large the compressor must be for a given output. A domestic unit holds only a few kilograms, yet that small charge dictates the safety rules, the service economics and increasingly which regulations apply to new equipment.
How are refrigerants classified?
Refrigerants are classified three ways: an R-number identifying the chemistry (ISO 817 / ASHRAE designations), a safety class combining toxicity letter (A = lower toxicity) with a flammability digit (1 = non-flammable, 2L = mildly flammable, 3 = flammable), and a GWP value stating climate impact relative to CO2. Blends carry 400- and 500-series numbers — R410A, for instance, mixes two HFCs to behave as a single fluid — and score the weighted GWP of their components.
| Refrigerant | Type | Safety class | GWP (AR4, as on datasheets) | Typical use |
|---|---|---|---|---|
| R410A | HFC blend | A1 | 2,088 | Legacy heat pumps and AC |
| R134a | HFC | A1 | 1,430 | High-temperature units, chillers |
| R32 | HFC | A2L | 675 | Current splits and monoblocks |
| R290 (propane) | Natural | A3 | 3 (≈0.02 in AR6) | New monoblock heat pumps |
| R744 (CO2) | Natural | A1 | 1 | DHW heat pumps, commercial systems |
Which refrigerants is the EU phasing out, and when?
Regulation (EU) 2024/573 attacks high-GWP HFCs from two directions. The quota side cuts the HFCs placed on the market: 42.9 Mt CO2e for 2025–2026 (about 48% below 2023), roughly 21.7 Mt for 2027–2029, near 9 Mt from 2030, and a full HFC phase-out by 2050. The equipment side bans categories outright: from 1 January 2027, new monoblock and air-to-water split units up to 12 kW may not use refrigerants with GWP ≥150; larger splits face GWP 750 from 2029 and GWP 150 from 2033; full F-gas bans follow for small monoblocks in 2032 and small splits in 2035.
Servicing is regulated too: virgin refrigerants with GWP ≥2,500 are banned for servicing stationary refrigeration since 2025, with the ban extending to air-conditioning and heat pump equipment from 2026 — recycled and reclaimed refrigerant keeps a transitional allowance, and the exact scope is worth checking against the current official text.
What does the refrigerant choice mean when buying a heat pump?
The refrigerant on the nameplate predicts the unit's service economics for the next 15 years. High-GWP refrigerants get scarcer and dearer every quota step; sub-150-GWP refrigerants such as R290 propane sit outside the phase-down entirely. Flammability class determines siting rules — the reason R290 dominates outdoor monoblock heat pumps rather than indoor-connected splits. From 12 March 2026, EU-wide installer training requirements cover natural refrigerants as well as F-gases, closing the competence gap. The full regulatory picture is mapped in the EU F-Gas guide.
Frequently asked questions
Which refrigerant is best for a heat pump in 2026?
For new small monoblocks, R290 propane is the emerging default: GWP near zero, outside the EU quota, and flow temperatures above 70 °C. R32 remains common in splits until the 2027 sub-12 kW limit; CO2 serves dedicated DHW and commercial designs.
Can my R410A heat pump still be serviced?
Yes. R410A's GWP of 2,088 sits below the 2,500 servicing-ban threshold, so servicing stays legal — but the shrinking HFC quota raises its price year by year, which is worth factoring into repair-or-replace decisions on older units.
Are natural refrigerants better than HFCs?
Climatically, decisively: R290 and CO2 have GWPs of about 3 or less versus hundreds to thousands for HFCs, and they are exempt from the EU phase-down. Technically each has a niche — R290 for high flow temperatures, CO2 for hot water — while flammability or high pressure shape the system design.
What does the A2L safety class mean?
Lower toxicity (A) and mild flammability (2L) — the class of R32. A2L refrigerants burn only within narrow conditions and with low flame speed, so they are permitted indoors under charge-dependent room-size rules, unlike A3 refrigerants such as propane.