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Now that you know what an air conditioning condenser is, it is time to learn about air conditioning compressors. Compressors are found inside the AC condenser that makes up the outside unit of your AC system. The role of the compressor is to compress the cool refrigerant that enters it so that the temperature of the refrigerant rises. The hot gas then leaves the compressor and enters the condenser where the cooling process starts. Essentially there are 5 different types of AC compressors that work in slightly different ways. We will explain each type in greater detail to help you better understand how your AC works.
This is the most commonly used type and is very versatile. It uses a piston and cylinder design to compress the refrigerant. Powered by a motor and crankshaft, the piston moves up and down inside the cylinder. The refrigerant is sucked into the cylinder by a vacuum that is created as the piston moves down. When the piston moves back up, it compresses the gas, which is then pushed into the condenser. Reciprocating compressors are very efficient and you can get AC units that have 2, 4, or even 8 cylinders in its compressor.
Scroll compressors are becoming more popular for use in HVAC systems as they are more reliable and efficient than reciprocating types. This is because they have fewer moving parts than in reciprocating compressors. It has one fixed scroll (it looks like a coil or spiral) that remains stationary and second moving or orbiting scroll that rotates through the use of swing link. As the second scroll moves, pockets of refrigerant between the two scrolls are slowly pushed to the center, compressing the refrigerant.
The screw compressor is very efficient and reliable when it comes to industrial use and is mostly used for big office buildings, factories, or other areas where a huge amount of air needs to be cooled continuously. This type uses two helical rotors that rotate and move the air from the compressor intake towards the end of the screws and the outtake. As the air moves from one end to the other, the space gets increasingly smaller, thus compressing the refrigerant.
Rotary compressors are usually very small, quiet, and reliable. It is made up of one or more vanes/blades that are attached to the cylinder shaft. The shaft is positioned off-center inside of a cylinder. As the shaft rotates, the blades move around the cylinder. The refrigerant intake is located where there is the most amount of space between the shaft and the cylinder wall. The outtake is located where the space is smallest between the shaft and the cylinder wall. As the shaft and vanes rotate, the refrigerant is moved towards the smallest space and is thus compressed.
Centrifugal compressor is mostly used for cooling large capacities of air. Because it is unique in that it uses centrifugal force, it has very few moving parts (no valve, piston, cylinder, or blades) and is highly reliable and efficient especially at higher speeds. Refrigerant gas is sucked into the center of the impeller (a disk with radial blades). The impeller spins rapidly inside the housing compartment. The refrigerant gains velocity inside this system and is compressed as it reaches terminal velocity at the outside edge of the impeller. At this point it is released into the condenser.
So, knowing whether an AC has a reciprocating or rotary compressor, or a screw or scroll compressor, will mean you can decide whether you are willing to sacrifice some silence for a more reliable and efficient unit, or vice versa. Keep checking our tips and blog to find out more about the other important parts of your AC unit, such as the evaporator, filters, ducts, and expansion valve.