What Is R32 Refrigerant and Why Is It Used in Heat Pumps?

What Is R32 Refrigerant and Why Is It Used in Heat Pumps?

Air source heat pumps use refrigerant to absorb heat energy from the outdoor air and transfer it into a property. Although the air outside may feel cold, it still contains usable thermal energy that a heat pump can collect and convert into heating and hot water.

R32 refrigerant is now widely used in modern air conditioning and heat-pump equipment. BPC Heat’s range includes Mitsubishi R32 air source heat pumps designed to provide an efficient alternative to traditional fossil-fuel heating systems. Mitsubishi Electric currently offers R32 Ecodan models in several outputs for different property requirements.

But what exactly is R32 refrigerant, how does it work and why is it used in air source heat pumps?

What is R32 refrigerant?

R32, also known as difluoromethane, is a hydrofluorocarbon refrigerant used in heating, cooling and refrigeration equipment.

Its role is to move heat from one place to another. Within an air source heat pump, R32 repeatedly changes pressure and state as it circulates through the system, allowing it to collect heat outside and release that heat into the property’s water-based heating system.

R32 has a Global Warming Potential, or GWP, of 675 under the measurement commonly used for refrigerant regulations. This is considerably lower than the GWP of 2,088 associated with R410A, a refrigerant commonly used in earlier generations of heating and cooling equipment. R32 also has zero Ozone Depletion Potential.

A lower GWP does not mean that R32 has no environmental impact. The refrigerant must remain contained within the system and must be correctly recovered rather than released into the atmosphere during servicing or decommissioning.

How does R32 work in an air source heat pump?

R32 refrigerant moves through a continuous cycle inside the heat pump.

1. Absorbing heat from the outdoor air

The outdoor fan draws air across the heat pump’s evaporator. The liquid refrigerant absorbs heat from the air and begins to evaporate into a gas.

2. Increasing the temperature

The refrigerant gas enters the compressor. Compressing the gas raises its pressure and temperature, producing the higher-temperature energy required by the heating system.

3. Transferring heat to the home

The hot refrigerant passes through a heat exchanger, where its energy is transferred to the water circulating through the property’s heating system.

This heated water can then be used for:

• Underfloor heating
• Suitable radiators
• Fan coils
• Domestic hot water through a compatible cylinder

As the refrigerant releases its heat, it cools and condenses back into a liquid.

4. Repeating the cycle

The refrigerant passes through an expansion device, which reduces its pressure and temperature. It then returns to the evaporator and begins the process again.

Mitsubishi Ecodan monobloc systems are self-contained outdoor units that require water and electrical connections to transfer heat into the property. The refrigeration cycle remains within the outdoor unit during normal operation.

What are the benefits of R32 refrigerant?

Lower GWP than R410A

One of the main reasons manufacturers moved from R410A to R32 was its lower Global Warming Potential.

R32 has a GWP of 675, compared with 2,088 for R410A. This means that, kilogram for kilogram, an accidental release of R32 would have a lower calculated global-warming impact than the same quantity of R410A.

Supports efficient heat-pump design

R32 has thermodynamic properties that allow it to absorb and release heat effectively. This supports the design of efficient and compact heating and cooling equipment.

However, the refrigerant alone does not determine how efficiently a heat pump will operate. Performance also depends on:

• Correct heat-pump sizing
• Property heat loss
• Heating flow temperature
• Radiator or underfloor-heating design
• Controls and zoning
• Hot-water demand
• Installation and commissioning

Our air source heat pump design guide explains why these factors must be considered before equipment is selected.

Single-component refrigerant

R32 is a single-component refrigerant rather than a mixture of several refrigerants. This can make the refrigerant more straightforward to recover, recycle and reuse correctly when equipment is serviced or reaches the end of its life.

Used in a broad range of heat-pump outputs

The Mitsubishi R32 range supplied by BPC Heat includes monobloc outdoor units in several outputs, including models designed for smaller homes and larger domestic heating requirements.

You can view our range of R32 air source heat pumps to compare the available outputs and compatible system components.

Is R32 refrigerant safe?

R32 is classified as an A2L refrigerant. This means it has lower toxicity and is mildly flammable.

The classification does not mean an R32 heat pump is unsafe during normal use. The refrigerant is contained within a purpose-designed sealed system, and the equipment includes safety requirements covering installation, positioning, servicing and refrigerant charge.

R32 should not be released, topped up or handled by an unqualified person. Work involving the refrigerant circuit must be completed by someone holding the appropriate qualifications. The official GOV.UK  guidance on qualifications required to work with F-gas explains the requirements for installing, servicing, checking and recovering refrigerant from heat-pump equipment.

Requirements can differ between Great Britain, Northern Ireland and Ireland, so the rules applicable to the project location should always be followed.

Does R32 make a heat pump quieter?

R32 can support compact and efficient heat-pump designs, but the refrigerant itself does not determine the operating noise of a unit.

Noise levels are influenced by factors such as:

• Fan and compressor design
• Heat-pump output
• Operating conditions
• Unit location
• Mounting and vibration control
• Distance from neighbouring properties

Mitsubishi Electric’s current R32 Ecodan range has been designed with low operating noise and flexible positioning in mind, but the published sound information for the individual model should always be checked before selection.

R32 compared with R410A

R410A is a blended refrigerant that was commonly used in older heat pumps and air-conditioning systems. R32 forms part of the R410A blend but can also be used on its own in equipment specifically designed for it.

The main differences include:

• R32 has a lower GWP of 675 compared with 2,088 for R410A.
• R32 is a single-component refrigerant.
• R32 is classified as A2L, meaning it is mildly flammable.
• R32 equipment must be designed specifically for R32 and cannot simply be substituted into an R410A system.

Refrigerants should never be changed or mixed unless this is expressly approved by the equipment manufacturer.

R32 compared with R290

R290 is a natural hydrocarbon refrigerant more commonly known as propane. It has a much lower GWP than R32, which is why its use in newer heat pumps is increasing.

The two refrigerants nevertheless have different properties and safety requirements. R32 is classified as A2L, while R290 has a higher A3 flammability classification. This can affect unit design, refrigerant charge, positioning and required clearances.

There is no single refrigerant that is automatically the best option for every property or heating application. The correct choice depends on the heat-pump model, required output, flow temperature, available installation space, manufacturer requirements and overall system design. R32 therefore remains a practical refrigerant for many current heat-pump applications.

Choosing the correct R32 heat pump

The refrigerant is only one part of an air source heat-pump system. Selecting the correct output and matching the unit with the correct cylinder, emitters and controls is essential for reliable operation.

BPC Heat’s instant ASHP quote provides quick preliminary sizing for a heat pump and cylinder, along with live kit pricing. It considers basic project details including floor area, occupancy, property type and cylinder requirements.

For projects requiring a more detailed assessment, our free heat-pump design service can help match the heating system to the property. A complete design can consider:

• Property heat loss
• Required heat-pump output
• Heating flow temperatures
• Radiator or underfloor-heating requirements
• Cylinder sizing
• Controls and zoning
• Compatible system components
• Installer-ready system information

BPC Heat supplies the equipment and system design, allowing your chosen installer to work from a specification developed around the property rather than selecting components using floor area alone.