Differences between R290 and R32 Heat Pumps

Heat pumps are essential in heating and cooling systems widely used in homes and commercial spaces. Choosing the right refrigerant for a heat pump is crucial as it impacts the system's energy efficiency, environmental impact, safety, and cost. Two common refrigerants used in heat pumps are R290 and R32, which have distinct characteristics and applications. The functioning and suitability of the heat pump primarily come down to the type of refrigerant they are using. This article explores the differences between R290 and R32 heat pumps.

What is R290?

R290 is a hydrocarbon refrigerant, also known as propane. It is used as a refrigerant in various cooling and heating applications, including heat pumps, air conditioners, and refrigeration systems. R290’s global warming potential (GWP) is three, rated low and way below the standard of 150, making it an environmentally friendly alternative to most other refrigerants like R22 and R410A. It also has a high latent heat of vaporization, which means that it can absorb a large amount of heat energy when it evaporates, making it an efficient refrigerant. 

However, R290 is flammable, so specific safety measures must be taken during installation, maintenance, and disposal to prevent fire hazards. Despite its flammability, R290 is increasingly used as a refrigerant in various applications due to its low environmental impact and high efficiency.

What is R32?

R32 is a refrigerant that is commonly used in air conditioning and heat pump systems. It is a member of the hydrofluorocarbon (HFC) family of refrigerants, which means that it does not contain chlorine and has a low ozone depletion potential (ODP). R32's global warming potential (GWP) is 675, significantly lower than many other refrigerants used in the past.

It is also more energy efficient than some other refrigerants, which can help to reduce operating costs over the lifetime of a system. R32 is not flammable but can be mildly toxic if inhaled in large quantities. Because of its low environmental impact and energy efficiency, R32 has become a popular choice for use in air conditioning and heat pump systems worldwide.

Differences between R290 and R32 Heat Pumps

The refrigerants bring their unique properties to the heat pumps, creating differences between them. The main differences between these heat pumps appear across the following area.

Refrigerant properties

Both heat pumps use different refrigerants. For instance, R290, also known as propane, has a lower global warming potential (GWP) and ozone depletion potential (ODP) than R32. R290 has a GWP of 3 and an ODP of 0, while R32 has a GWP of 675 and an ODP of 0.

Efficiency

R32 has a higher volumetric cooling capacity than R290, which means that R32 heat pumps are more efficient in terms of cooling power per unit volume of refrigerant. R32's cooling capacity per unit volume  is approximately 87% more than R290's. An R290 system would need a compressor with a higher displacement to maintain the same cooling load.

Safety

R290 is flammable and requires specific safety measures to be taken during the installation and maintenance of R290 heat pumps. 

On the other hand, R32 is not flammable but can be mildly toxic if inhaled in large quantities. If you choose safety, ensure you have the right setup for your preferred heat pump. 

Availability

R32 is more widely used in heat pumps than R290, so it may be more readily available and easier to find replacement parts for R32 heat pumps than R290 heat pumps. 

Cost

The cost of R290 is generally lower than R32 due to its lower GWP and ODP values. Therefore, R290 heat pumps are cheaper than R32. However, the cost of the heat pump itself may vary depending on the manufacturer, size, and features.

Operating pressures

R32 operates at a higher pressure than R290. This can make its heat pumps more suitable for use in larger systems where higher pressure is required, but it can also make it more difficult to handle and maintain than R290 heat pumps. 

Environmental impact

While R290 has a lower GWP than R32, it is also a hydrocarbon refrigerant that can contribute to smog formation if leaked into the atmosphere. R32, on the other hand, is a fluorocarbon refrigerant that can contribute to global warming if released.

Efficiency in colder temperatures

R290 heat pumps have a higher coefficient of performance (COP) than R32 heat pumps at lower outdoor temperatures, making them a better choice for cold climates. R32 heat pumps, on the other hand, perform better at higher outdoor temperatures.

Energy consumption

R32 heat pumps generally consume less energy than R290 heat pumps due to their higher efficiency. This aspect can result in lower operating costs over the system’s lifetime and may compensate for the initial high price. 

Noise level

R32 heat pumps tend to be quieter than R290 heat pumps due to their lower operating pressures and smoother operation. This can be an important consideration in residential settings where noise levels can be a concern.

What to consider when picking between R290 heat pumps and R32 heat pumps

The choice between R290 and R32 heat pumps depends on various factors, including the specific application, regulatory requirements, safety concerns, and personal preferences. Here are a few factors to consider when choosing between the two options:

When can one use R290 heat pumps?

Here are some situations where R290 heat pumps may be a good choice specifically for heating and cooling systems:

1. You need small-to-medium-sized heat pumps: R290 is suitable for small to medium-sized heating and cooling systems, such as residential homes, small businesses, and offices. Its high-energy efficiency and low operating costs make it an attractive option for these applications.

2. Cold climates: R290 has a high coefficient of performance (COP) at low ambient temperatures, making it a good choice for heating applications in cold climates. It can provide reliable and efficient heating even when temperatures drop below freezing.

3. Environmentally friendly systems: As mentioned earlier, R290 has a very low global warming potential (GWP) of 3, which makes it an excellent choice for environmentally friendly heating and cooling systems. It is also non-corrosive and non-toxic, making it a safe and reliable option.

4. Residential and commercial setups: R290 heat pumps can be used in both residential and commercial applications, such as homes, offices, and retail spaces. They can provide efficient and reliable heating and cooling while reducing environmental impact.

5. Retrofitting existing systems: R290 can be used to retrofit existing heating and cooling systems that use other refrigerants. This can provide energy savings and reduce environmental impact without the need for a complete system replacement.

When is it best to use R32 heat pumps?

R32 is a commonly used refrigerant in heat pumps due to its high energy efficiency, low environmental impact, and regulatory compliance. Here are some situations where R32 heat pumps may be a good choice:

1. Energy efficiency: R32 has a high coefficient of performance (COP), which means it can provide more heating or cooling output for the same amount of energy input as other refrigerants. This makes it an excellent choice for applications where energy efficiency is a priority, such as in residential and commercial buildings.

2. Regulatory compliance: R32 complies with the latest refrigerant regulations, such as the EU's F-Gas regulation, which aims to phase out the use of high-GWP refrigerants. R32 has a low global warming potential (GWP) of 675, much lower than older refrigerants like R410A.

3. Safety: R32 is classified as an A2L refrigerant, which means it has a low flammability rating and is considered safe for heating and cooling systems. It is also non-toxic and non-ozone depleting, making it a safe and environmentally friendly option.

4. Availability: R32 is widely available and can be used in various heat pump systems, making it a convenient and cost-effective option.

5. Cost: R32 can be a cost-effective option for heat pumps due to its high energy efficiency and low operating costs. It also requires less refrigerant than other refrigerants like R410A, which can reduce installation and maintenance costs.

Choosing the proper refrigerant for a heat pump is a critical decision that can impact the system's efficiency, safety, cost, and environmental impact. R290 and R32 are two common refrigerants used in heat pumps, each with unique characteristics and applications. 

While R290 is a suitable choice for environmentally friendly applications, small and medium-sized applications, and cold climates, R32 is commonly used for energy efficiency, regulatory compliance, safety, and availability. It is essential to consult with a qualified HVAC professional to determine which refrigerant is the best choice for your specific application.