Basic Information About Compressors

July 9, 2014


Understand your HVAC system better by learning about its various components, for example, the compressor.

hvac-compressorCompressors are mechanical devices offering a number of different functions. One example of a compressor is a pump. There are different functions and types of compressors.

A Compressor and Its Uses

HVAC compressors are refrigerant gas pumps where vaporous refrigerant is supplied by an evaporator at low pressure before its pressure is increased. Once the gas is compressed, its pressure and temperature will increase. The condenser will receive the vaporous refrigerant at a pressure where condensation will happen at a suitable temperature level.

A compressor is made up of two components, the source of the power and the compressing component, such as a vane or piston. The compressing component of an air compressor packs atmospheric pressure together. The following is the process of how an air compressor functions:

  1.  Air goes into the vane or piston before pressure is increased and volume is decreased to compress the air.
  2. Once the maximum pressure limit set by the operator is reached, air intake is stopped through a switch on the compressor.
  3. The pressure levels go down when the compressed air is being utilized.
  4. Air is allowed to go into the compressor once the minimum pressure level set by the operator is attained.
  5. The process will continue unless the compressor is turned off.

Factors Affecting the Performance of a Compressor

The performance of a compressor is affected by a number of factors, which are rotation speed, absorption pressure, discharge pressure, and type of refrigerant used. Comparable compressors are capable of operating at various capacities by simply changing the refrigerant and power input of the compressor. It is essential for buyers to determine some features when they aim to purchase certain kinds of compressors. These features include the cost of operation, price, operation type, and configuration of the device. It is also important to look at the compressor performance and ask for recommendations from the manufacturer on the most appropriate and most secure compressor that is suitable to meet the requirements and budget of the buyer.

Types of Compressors

The most common types of compressors utilized in refrigeration are as follows:

Rotary Compressors: These compressors are normally low capacity devices. They are typically used for home freezers and refrigerators. These compressors cannot be used for air conditioning units. The vane of single-vane compressors is attached to the rotor inside the body. The vanes of multi-vane rotary compressors are also positioned on the rotor.

Centrifugal Compressors: These are high-speed compressors where centrifugal force is used in compressing the refrigerant. Refrigerants with high specific volumes use this type of compressor since it requires a low compression ratio. To achieve higher discharge pressures, multi-stage units are utilized. The discharge temperature of the gas when it goes out of the rotor dictates the number of stages the compressor will have. These compressors are mainly used in cooling water of air conditioning units as well as freezing water at lower temperatures.

Reciprocating Compressors: These compressors have pistons which reciprocate inside the cylinders thus providing suction of refrigerant at low pressure and discharge at high pressure. The two kinds of reciprocating compressors are the hermetic compressors and open compressors.

Now that you know a little more about your HVAC system, take it as a first step towards its better care and maintenance. Call Scott-Lee Heating Company at (314) 200-0788 to schedule maintenance for your HVAC system.

Photo credit: Steve Johnson via Flickr