Which refrigerants are available for heat pumps?

Refrigerants play a central role in the operation of heat pumps. They are responsible for the heat transfer and therefore the efficiency of the system. With increasing environmental requirements and legal requirements, choosing the right refrigerant is becoming increasingly important. In this article, you can find out which options are available, what are their advantages and disadvantages and what the future of refrigerants looks like.

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What are refrigerants in heat pumps?

Refrigerants Are special fluids that transfer heat into heat pumps and thus enable the heating or cooling process. They absorb heat at a low temperature and release it again at a higher temperature, creating a thermodynamic cycle.

In a heat pump, the refrigerant goes through four phases.

1. First, it Evaporates in Evaporator. By absorbing heat from ambient air, soil or water.
2. It is then used in Supercharger Compressions, increasing pressure and temperature.
3. Thereafter, the Refrigerant is released in condenser The absorbed heat is transferred to the heating system and liquefies again.
4. In the last step, the refrigerant is Expansion valve Relaxes, causing pressure and temperature to drop. The cycle then starts all over again.

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This function makes refrigerant an indispensable part of every heat pump. It decisively determines the efficiency and environmental friendliness of the plant. Choosing the right refrigerant therefore not only influences the performance but also the sustainability of your heat pump.

Which refrigerants are used in heat pumps?

Both natural and synthetic refrigerants are used in heat pumps. These refrigerants vary in their environmental compatibility, efficiency and handling.

Natural refrigerants Are particularly environmentally friendly as they have a low global warming potential (GWP). Most commonly used in heat pumps CO2 (R744), Propane (R290) and ammonia (R717) used.

synthetic refrigerants Are manufactured industrially and offer a wide range of uses. Examples include R32 ROAD and Hydrofluoroolefins (HFO) such as R1234ze.

The following is an overview of the refrigerants used in heat pumps:

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What are the advantages and disadvantages of natural and synthetic refrigerants?

Natural refrigerants Such as CO2, propane and ammonia are environmentally friendly as they have very low or no global warming potential (GWP). They are considered future-proof due to their ease of regulation. They also offer high energy efficiency and are often cost-effective. Disadvantages include increased flammability (e.g. propane) or toxicity (e.g. ammonia), which requires safety measures. They also require special technical adjustments, such as high pressure resistance with CO2, which can increase system costs.

synthetic refrigerants Such as R32 or HFOs offer versatility and high safety standards, as they are usually not toxic or only difficult to burn. They are established in many existing systems and have a proven infrastructure. Disadvantages, however, include their often high global warming potential, which will partially ban them from 2025. Alternatives such as HFOs may be more environmentally friendly, but they are more expensive and less common.

Here is an overview of the advantages and disadvantages of the respective refrigerants for heat pumps:

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Which legal requirements apply from 2025?

From 2025, no new heat pumps and air conditioning systems may Refrigerants with global warming potential (GWP) Used by over 750 more. This regulation is part of the EU F-gas regulation, which promotes climate protection and is intended to promote the use of more environmentally friendly alternatives.

Synthetic refrigerants such as R410A, which have been used frequently so far, are particularly affected. Natural refrigerants such as CO2 (R744) and propane (R290) as well as synthetic alternatives with low GWP, such as R32 or HFO refrigerants (e.g. R1234ze), remain permitted.

Plant operators are also required to carry out leak tests on existing systems and to dispose of refrigerants in an environmentally friendly manner.

How do I choose the right refrigerant for a heat pump?

The right refrigerant for a heat pump is selected based on the criteria of environmental compatibility, efficiency and safety. These factors not only influence the performance of the plant, but also its sustainability and compliance with legal requirements.

• environmental sustainability Is crucial, as refrigerants with a high GWP will no longer be allowed in new systems from 2025. Natural refrigerants such as CO2 (R744) or propane (R290) are future-proof alternatives here.
• Efficiency Also plays a role, as refrigerants such as propane or R32 enable energy-efficient operation due to their thermodynamic properties.
• Safety aspects Such as flammability or toxicity should also be considered when choosing, as they influence installation costs and operational safety.

The choice ultimately depends on the intended use — for example, natural refrigerants are well suited for environmentally conscious households, while synthetic alternatives are often more practicable in existing systems.

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Sustainability and future trends in refrigerants

The development of refrigerants shows a clear trend away from high-GWP HFCs towards natural alternatives such as CO₂ and propane as well as synthetic HFOs. Statutory requirements, such as the phase-down plan of the EU F-gas regulation, are gradually reducing the permitted amount of refrigerants with high GWP by 2030. The graph shows how the use of such refrigerants is falling from 93% (2015) to just 21% (2030).

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Research and Innovation focus on the development of natural refrigerants and their use in more efficient systems. Future Technologies such as magnetic cooling or thermoelectric processes could supplement or replace refrigerants in the long term. This supports the goals of climate neutrality and makes heat pumps more sustainable.

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Image source: Federal Environment Agency