Air Conditioning Terms that are Helpful.


When researching an AC unit for purchase, you will probably come across quite a few terms that you are unfamiliar with. Here are some of the most common air conditioning terms to help you decide on the best possible AC unit for your home.

Air Conditioning- The process of controlling the humidity, cleanliness, temperature, and distribution of air.

Air Standard Conditions- The conditions used during capacity ratings in which air conditioning equipment is being tested.

Bimetal- Two metals that expand at different rates. When heated or cooled they warp and are able to be used to open or close a valve or switch.

British Thermal Unit (BTU)- The amount of heat needed to increase the temperature of 1 pound of water 1 degree Fahrenheit.

Check Valve- A valve that has been designed to only allow flow in one direction.

Compression- The use of mechanical equipment to reduce the volume of vapor or gas.

Conduction- The movement of heat from one molecule to another within a substance.

Convection- A transfer of heat through a moving fluid.

Evaporative Cooling- Cooling effect of a liquid’s vaporization in a moving air stream.

Refrigerant- A substance that produces refrigerating effects by vaporizing or expanding.

Refrigeration Velocity- The rate, in feet per minute, at which refrigerant moves through a unit.

Refrigeration- A transfer of heat from an unneeded place to its desired place.

Reversing Valve- An electronically controlled device, located in the heat pump that reverses the flow of the refrigerant when the unit changes between heating and cooling.

Riser – A tube that is vertical and carries refrigerant from a lower to higher level.

Slugging- A condition causing possible damage in which an amount of liquid enter the compressor, causing hammering.

Static Pressure- Normal force per unit area at a designated small hole located in the wall of a duct.

Suction Line- A tube that conveys refrigerant vapor to the suction inlet of the compressor from the evaporator outlet.

Temperature- The measurement of heat intensity.

Thermostat- A bimetal actuated switch that closes and opens a circuit in order to start or stop the function of a heating or AC system.

Trap- A dip or depression in piping where oil collects. It can be placed at the bottom of of a suction or hot gas riser in order to improve oil return up through the riser.

Vapor Pressure- Pressure exerted by vapor.