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Choosing the Right Compressor for Your Heat Pump

Do you know that in 2019, there were over 239,000 people in the UK using heat pumps in their homes? This number has been steadily growing over the years. If you don’t want your home to turn into an oven in the summer or a refrigerator in the winter, a heat pump is undoubtedly the best choice.

These incredible devices are capable of efficiently regulating temperatures, ensuring your comfort in any season. But have you ever wondered about the different types of heat pumps available in the market?

The compressor plays a crucial role in determining the efficiency of a heat pump, so it’s essential to understand the different types of compressors used before making a purchase.

Join us as we explore in detail the various types of compressors used in heat pumps and how to choose the best option.

What is a heat pump?

A heat pump is a household appliance designed specifically to transfer heat into a room during cold seasons and extract cold air into a room during hot seasons. Technically, heat pumps employ an inverter design, functioning similarly to both a refrigerator and a heater, depending on your needs.

The integrated technology in these devices eliminates the need for separate air conditioning or heating systems. Additionally, heat pumps are quite energy-efficient compared to most traditional HVAC systems.

A good heat pump can maintain a stable temperature of 21 degrees Celsius or provide 90% warmth even when the temperature drops to minus 20 degrees Celsius.

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Choosing the Right Compressor for Your Heat Pump

How does the compressor work?

The compressor plays a vital role in the operation of a heat pump. It is responsible for pumping the refrigerant gas into the system and creating the necessary pressure difference for heat transfer. These devices are located in the outdoor unit of the heat pump and are driven by an electric motor.

Technically, when the heat pump is in heating mode, the compressor draws in low-pressure, low-temperature refrigerant gas from the evaporator coil of the outdoor unit and compresses it into high-pressure, high-temperature gas.

The high-pressure gas is then transported to the condenser coil of the indoor unit, where it releases heat to heat the indoor air. After releasing the heat, the refrigerant gas is cooled and condenses into a liquid through the fan of the indoor unit.

Types of compressors in heat pumps

There are various types of compressors used in heat pumps. However, currently, most typical mainstream models belong to the following categories.

Reciprocating Compressors

Reciprocating compressors are the most common type among numerous heat pump models. They work by compressing the refrigerant gas and moving it through the heat pump system, transferring heat from one place to another.

In the heating cycle, the gas typically absorbs heat from the air or ground outside the building and releases it indoors. In the cooling cycle, the process is reversed, with the refrigerant absorbing heat from inside the building and releasing it outside.

The refrigerant extracts low-pressure/low-temperature refrigerant gas from the evaporator coil of the indoor unit and compresses it into high-pressure/high-temperature gas. The high-pressure gas is then transported to the condenser coil of the outdoor unit, releasing heat to the outdoor air.

After releasing the heat, the refrigerant gas is cooled and condensed into a liquid by the fan of the outdoor unit, and the whole process repeats. This is an essential cyclic process that ensures you achieve the desired indoor temperature.

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Scroll Compressors

Scroll compressors are known for their high efficiency, quiet operation, and reliability. This is because they use two interlocking spiral or scroll-shaped plates to compress the refrigerant gas. The device is located in the outdoor unit, typically outside the building.

In the heating cycle, the compressor draws in low-temperature refrigerant gas from the evaporator coil of the outdoor unit and compresses it into high-temperature gas. The gas is then transported to the condenser coil of the indoor unit, where it releases heat, heating the indoor air.

After releasing the heat, the refrigerant gas is cooled and condensed into a liquid through the fan of the indoor unit. In the cooling cycle, this process is reversed. The compressor draws in low-pressure, low-temperature refrigerant gas from the evaporator coil of the indoor unit and compresses it into high-pressure gas.

Compared to other compressors like reciprocating compressors, scroll compressors have several advantages. They have fewer moving parts, reducing the likelihood of mechanical failures. Additionally, they produce lower noise. Moreover, scroll compressors are more energy-efficient compared to other types of compressors and provide better temperature control.

Screw Compressors

These compressors are commonly used in large commercial and industrial heat pump systems due to their high efficiency and reliability. They utilize two rotors with spiral blades that rotate and compress the refrigerant gas as it passes through the compressor.

Like most compressors, screw compressors are located in the outdoor unit and driven by an electric motor. In the cold season, the compressor produces heat by compressing low-temperature refrigerant gas in the evaporator coil of the outdoor unit into high-temperature gas.

Then, the high-pressure gas is transported to the condenser coil of the indoor unit, releasing heat and raising the indoor air temperature. After releasing the heat, the refrigerant gas is cooled and condensed by the fan of the indoor unit.

During the hot season, this process is reversed. It’s worth noting that screw compressors have several advantages compared to other compressors. They are highly efficient, capable of providing a large volume of refrigerant gas with relatively low power input. Screw compressors are also highly reliable, requiring minimal maintenance, making them an ideal choice for large-scale heat pump systems.

Centrifugal Compressors

If you’re looking for an efficient heat pump for large commercial or industrial applications, centrifugal compressors are your best choice. They use rapidly rotating impellers to accelerate and compress the refrigerant gas, producing high-pressure gas that can be used for heating or cooling.

While they may be more expensive than other compressors, they can handle a significant volume of gas and require minimal maintenance. In the heating cycle, the compressor draws in low-temperature refrigerant gas from the evaporator coil of the outdoor unit and accelerates it through the rapidly rotating impellers.

The accelerated gas enters the diffuser, converting kinetic energy into pressure, producing high-temperature gas. Then, the gas is sent to the condenser coil of the indoor unit, where it releases heat, heating the indoor air.

In the cooling cycle, this process is reversed. One of the significant advantages of centrifugal compressors is their relatively low noise levels and minimal maintenance requirements. While centrifugal compressors may be slightly more expensive than other compressors and may require specialized installation and maintenance procedures, they are quite efficient for large-scale applications.

Rotary Air Conditioning Compressors

These compressors are the ideal choice when searching for compressors for residential and commercial heat pump systems. Their high operational efficiency and compact size make them the best option. They utilize rotary blades or vanes to compress the refrigerant gas, providing high-pressure output with low vibration and low noise.

While they may not be suitable for large systems, they are an excellent choice for small heat pump models. Their functioning is similar to other compressors. In the refrigeration cycle, the compressor draws in low-temperature refrigerant gas from the evaporator coil of the indoor unit and compresses it into high-temperature gas.

Then, the gas is transported to the condenser coil of the outdoor unit, releasing heat to the outdoor air. Finally, the outdoor unit’s fan cools the refrigerant gas and condenses it into a liquid. Rotary air conditioning compressors have the advantage of being compact in structure and lightweight, making them ideal for small-scale heat pump systems.

Additionally, they operate with low levels of vibration and noise, requiring minimal maintenance. The only drawback is that they may not be suitable for large-scale heat pump systems that require high output capacity.

Which type of compressor is suitable for a heat pump?

The best type of compressor depends on the type and size of the heat pump, operating conditions, and the required heating and cooling capacity. Technically, each type of compressor has its advantages and disadvantages, and the choice of compressor depends on the specific needs of the system.

For example, reciprocating compressors are a popular choice for small and medium-sized heat pump systems due to their high efficiency and relatively low cost. However, they may not be suitable for large systems or systems that require high output capacity.

On the other hand, scroll compressors are also an ideal choice for small and medium-sized heat pump systems due to their compact structure, high efficiency, and low noise. They may not be suitable for large systems or systems that require high output capacity.

Screw compressors are typically used in large commercial or industrial heat pump systems as they can provide high output capacity and efficiency. However, compared to other types of compressors, screw compressors are more expensive and require more maintenance.

Centrifugal compressors are an excellent choice for large-scale heat pump systems that require high capacity at high pressure ratios. While they may be more expensive and require specialized installation and maintenance, they are quite efficient in large applications.

Rotary air conditioning compressors are ideal for residential and small commercial heat pump systems. Their efficient operation and compact size make them a great choice. However, they may not be suitable for large systems or systems with high output requirements.

Final Thoughts

The compressor in a heat pump is undoubtedly the most critical component that ensures you get the desired heating or cooling, keeping you comfortable in different seasons. Now that you have learned about the different types of heat pump compressors, you can choose the one that best suits your preferences.

At Shengling, we take pride in being a world-class company that provides high-quality heat pump solutions to our customers. If you have any heat pump needs, feel free to contact us, and let us ensure that your home remains at the desired temperature.

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