Superheat		A space partially exhausted by artificial means (i.e., suction measured in inches of Hg in a low pressure chiller).
Retrofit		Any foreign object or substance not normally found in a specific location.
Evaporation		Heat exchanger where the system heat is absorbed and the refrigerant evaporates into a gas. By continually pulling refrigerant vapor out of the evaporator headspace, low pressure can be maintained causing the refrigerant to evaporate rapidly. Evaporation cools the refrigerant. This cold refrigerant produces chilled water by heat transfer. The evaporator side is commonly referred to as the closed loop system (chill water).
Strainer		British thermal unit. The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Compressor		When energy is added to an object or location, the motion of the molecules increases causing them to collide more frequently. The motion energy is converted into heat during the collisions. As more collisions occur more heat is released and the temperature of the object or location increases.
Thermometer		The process a vapor goes through to change phase from vapor to a liquid.
Heat		Refrigerant
Vacuum		Is the temperature difference between the boiling point of the refrigerant in the evaporator and the actual temperature of the refrigerant gas after the evaporator. It is the “extra” temperature (or temperature rise) the refrigerant picks up in the evaporator after it boils.
ARI		The practical meter-kilogram-second unit of electric current that is equivalent to a flow of one coulomb per second or to the steady current produced by one volt applied across a resistance of one ohm.
Ampere		A mechanical device where the refrigerant is compressed from a lower pressure and lower temperature to a higher pressure and higher temperature. The compressor maintains a low pressure in the evaporator by continually removing refrigerant vapors. This low pressure, low temperature vapor is then compressed into a higher pressurize, hot refrigerant vapor which leaves the compressor and travels to the condenser. The motor in the compressor is the main consumer of energy in the chiller system. The energy used by the compressor is dependent on the pressure increase. The head pressure divided by the suction pressure or the condenser pressure divided by the evaporator pressure expresses this. If the compressor operates out of its original design, it will effect the energy consumption.
BTU		Heat exchanger where the system heat is rejected and the refrigerant condenses into a liquid. The condenser is where hot pressurized refrigerant vapors in the compressor are cooled and liquefied by cooling tower water circulating through the tubes of the condenser. The condenser side is commonly referred to as the open recirculation system or open loop.
Subcooling		A retrofit is a modification to a chiller system. For example, a new style compressor replacing an older, less efficient style or to use a different refrigerant to comply with new standards. The results can affect energy efficiency.
Condenser		Used as the lubricant in the compressor system to lubricate and protect bearings, shaft, etc.
Contamination		Air Conditioning and Refrigeration Institute
Pressure		The process a liquid goes through to change phase from a liquid to a vapor.
Oil		Degree of hotness or coldness of an object or location measured on a definite scale.
Gauge		The application of force to something by something else in direct contact with it.
Seal		The design capacity of a pump’s ability to circulate fluid.
Evaporator		Liquid refrigerant cooled below the condensing temperature of the refrigerant.
Condensation		Measures and evaluates temperature.
Pump		An instrument or device for measuring, indicating or comparing a physical characteristic, i.e., temperature or pressure.
Temperature		A seal is a tight and perfect closure (as against the passage of gas or water) or a device to prevent the passage or return of gas or air into a pipe or container.
Refrigerant		Used to remove foreign material from the water flow. The mesh size determines the size of the material/debris being removed.