Refrigerants in heat pumps – R290, R32 and how the choice affects the future

A refrigerant is the fluid that enables a heat pump to transfer heat. It circulates in a closed system and absorbs heat from rock, ground, water, or outdoor air, and then releases that heat inside the house.

Because the refrigerant can switch between liquid and gaseous states even at low temperatures, the heat pump can utilize stored energy in nature and convert it into heating and domestic hot water.

In short: without refrigerant, a heat pump cannot operate.

The choice of refrigerant affects several key characteristics of a heat pump, including:

• how efficiently the heat pump operates

• the temperatures it can deliver

• how stable its performance is at low outdoor temperatures

• the overall environmental impact of the heat pump

This is also why refrigerants have gained a more central role in the development of modern heat pumps, as requirements for energy efficiency and sustainability continue to increase.

In a heat pump, the refrigerant operates in a continuous cycle where heat is absorbed, raised to a usable temperature level, and transferred to the home’s heating system. Simplified, the process can be divided into five steps:

1. Heat is absorbed from the energy source.
   The refrigerant absorbs heat from rock, ground, water, or outdoor air, even when temperatures are low.

2. The refrigerant turns into gas.
   When heat is absorbed, the refrigerant evaporates and carries the energy further through the system.

3. The temperature is increased through compression.
   The gaseous refrigerant vapor is compressed, which raises the temperature to a level suitable for heating and hot water production.

4. Heat is transferred to the home.
   The heated energy is transferred to the house’s heating system.

5. The refrigerant cools down.
   It returns to liquid form and the process starts again.

This cycle is the foundation of how heat pumps can deliver heat with high efficiency, even in cold climates.

How a refrigerant behaves in practice affects both the performance of the heat pump and how the system needs to be designed. For that reason, refrigerants in heat pumps have evolved gradually over time, in line with changing requirements for energy efficiency, environmental impact, and long-term use. Each refrigerant has been a response to the technical conditions of its time.

R410A

For many years, R410A was a common refrigerant in heat pumps thanks to its good technical properties and stable operation. It enabled efficient system solutions, but has a relatively high environmental impact, which has led the industry to look for alternatives over time.

R32

R32 was introduced as a step toward lower environmental impact, while still allowing manufacturers to build on existing heat pump technology. Compared with R410A, R32 has improved environmental characteristics and enables high energy efficiency, which has made it an attractive option in many heat pumps. At the same time, R32 is based on the same fundamental system architecture as earlier generations of refrigerants.

R290

R290, also known as propane, is a natural refrigerant that has taken on a clear role in the development of modern heat pumps. With very low environmental impact and strong thermodynamic properties, it enables efficient system solutions even at higher temperatures.

At the same time, using R290 represents a shift in how heat pumps are designed. The properties of the refrigerant place higher demands on system design, component selection, and installation, meaning that the overall system – not just the refrigerant itself – becomes crucial to the final result.

In summary, development is not about one refrigerant suddenly replacing another, but rather about a gradual adaptation to new requirements. Against this background, manufacturers such as CTC have chosen to work with refrigerants designed to meet long-term demands for both performance and sustainability, rather than short-term optimizations.

When you choose a heat pump, the refrigerant is already part of the design. In other words, you do not choose the refrigerant separately – but the choice of heat pump also means choosing the refrigerant and the characteristics that come with it.

The refrigerant influences, among other things:

• the temperatures the heat pump can deliver

• how efficiently the system performs at low outdoor temperatures

• how the heat pump is designed and installed

This means that two heat pumps with similar performance data can function differently in practice depending on which refrigerant they are designed for.

Today, refrigerants such as R32 and R290 are primarily used, representing different technical approaches. Heat pumps with R32 build on established system technology, while heat pumps with R290 are designed around a different system concept that enables higher temperature capacity, but also places higher demands on system design and installation.

Ultimately, it is not the refrigerant itself that determines whether a heat pump is the right choice, but how well the entire system is adapted to the house, the climate, and long-term use.

The refrigerant is a central part of how a heat pump works, but it should never be viewed in isolation. The development from R410A to R32 and further to R290 reflects how requirements for energy efficiency, performance, and long-term sustainability have evolved over time.

In practice, it is the interaction between refrigerant, system design, and installation that determines how well a heat pump performs in everyday use – and how well the investment holds up over time.

At CTC, we view the refrigerant as part of the heat pump’s total system, not as an isolated choice. The focus is on how design, safety, and installation work together to create solutions that operate reliably over time in Nordic climates.

The refrigerant is always an integrated part of the heat pump’s design. One example of how this is implemented in practice is an air-to-water heat pump using R290, where the refrigerant is part of the overall system solution – such as the CTC EcoAir 700M.