Complete guide to understanding the different types of AC compressors

The air compressor is the noisiest component of an AC because it’s a large, powerful motor that continuously compresses the refrigerant and re-circulates it through your AC. This is a critical step in the cooling process as compressing the refrigerant raises its pressure and temperature, making it easier to dissipate the heat it absorbed before it’s sent back to draw the heat out of your room and cool it.

Manufacturers use different designs for these compressors, each with their own pros and cons, but the basic function remains the same.

ALSO READ: What is a compressor?

That said, here are some of the most popular air conditioner compressor types in use today:

1. Inverter and non-inverter ACs

2. Reciprocating compressor

3. Scroll compressor

4. Rotary screw compressor

5. Centrifugal compressor

1. Inverter and non-inverter ACs

One thing we do need to get out of the way is the difference between inverter and non-inverter ACs. Inverter ACs use a variable speed motor – a.k.a. an inverter-controlled motor – for the compressor. Using such a motor can result in significant cost savings while reducing wear and tear. 

ALSO READ: Standard inverter vs digital inverter: Which compressor is better for your refrigerator?

This is because ACs without inverter control run their motors at full speed and only stop or start them to control the cooling. Inverter control allows the compressor to run at a lower speed when maximum cooling is not required, thus saving resources.

2. Reciprocating compressor

This is one of the oldest compressor designs. A cylinder holds the refrigerant and a piston moves up and down compressing the gas, pumping it out, and then creating a vacuum to suck in fresh gas. The design is much like a car engine, and like a car engine, multiple cylinders can be used to improve compression capacity and efficiency. This design is generally used in older and cheaper AC systems, and is also sometimes found in large, commercial AC systems.

3. Scroll compressor

This is an interesting design involving two spirals inside a cylinder. One spiral is fixed and the other moves relative to the other. The shape of the spirals compresses the refrigerant and forces it towards the centre, where it’s ejected out of the top or bottom of the cylinder. This is a simple design and very efficient, but tends to be more expensive and is thus found in more premium AC designs.

4. Rotary screw compressor

Sometimes used in large, commercial applications, a rotary or screw compressor uses a rapidly rotating screw to guide the air from the inlet to the outlet and compress it along the way. As with any screw, the gas or fluid can only move in one direction based on the direction of rotation.

5. Centrifugal compressor

These designs are similar to jet engines. Air is essentially hurled to the edges of a cylinder and compressed using an impeller – a fan-like device designed to move the air outwards as it rotates. This added kinetic energy compresses the air and heats it up. Of course, a refrigerant is used instead of air in the case of ACs. This design tends to be complex and quite powerful, which is why you’ll more often than not find centrifugal compressors used in commercial spaces.

As one of the most important and power-hungry components in an AC, it’s important to choose the right compressor for the job at hand. To be fair, however, this choice only really matters when comparing options for commercial spaces. The average consumer need only concern themselves with the cost of an AC, whether its using inverter control or not, and its star rating for energy efficiency.

However, having said that, armed with this knowledge of the different AC compressor types, you can ensure you invest in the right one for yourself and ensure maximum savings in the long run.