Calibrate – To determine accurate measurements and reset instrument to these settings.

Calibration - To correct any error an interment reads

Calorie - the amount of heat ( by weight) that is required to raise the temperature of water 1 degree Celsius.

Calorimeter - Device used to measure the quantities of heat.

Cam - Mechanical component that is oblong, giving a reciprocating mo­tion when rotated.

Capacitive Reactance - The opposition to alternating current as a result of capacitance; expressed in ohms.

Capacitor-Start Motor - A motor that requires a capacitor in the start­ing circuit.

Carbon Dioxide - Compound of carbon and oxygen, is sometimes used in refrigerants

Carbon Filter - Air filter housing activated carbon.

Carbon Monoxide - Colorless, odorless, and poisonous gas pro­duced when carbon or carbonaceous fuels incorrectly burnt.

Carbon Tetrachloride - a chemical used as a solvent for removing grease oil and sludge.

Cascade System - Arrangement in which two or more refrigerating systems are used in series.

Cathode - Negative terminal of an electrical device.

Cavitation - Localized gaseous condition that is found within a liquid stream.

Celsius Temperature Scale - Temperature scale used in metric system. 

Centimeter - Metric unit of linear measurement.

Centrifugal Compressor - A compressor employing centrifugal force for compression.

Centralized Computerized Controller - Energy control device,  centrally located, which makes control decisions based on operating data, programmed information, and stored data.

Central Station - Central location of condensing unit with either wet or air-cooled condenser. Evaporator located as needed and connected to the central condensing unit.

Change of State - the point at witch a substance changes from a solid to a liquid or a liquid to a gas due to addition of heat. Or, the reverse, in which a substance changes from a gas to a liquid, or a liquid to a solid, due to removal of heat.

Charles' Law - Volume of a given mass of gas at a constant pressure varies according to its temperature.

Chemical Refrigeration - System of cooling using a disposable refrigerant.

Chill Factor - Calculated number based on temperature and wind velocity.

Chimney -Vertical shaft for carrying flue gases to the outside atmosphere.

Chimney Connector – A pipe connecting the heating appliance with the chimney.

Chimney Effect - Tendency of air or gas to rise when heated.

Chimney Flue - The passageway in a chimney.

Choke Tube - Throttling device used to maintain correct pressure dif­ference between high side and low side in refrigerating mechanism.

Circuit -  Tubing, piping, or electrical wire installation which permits continuous flow.

Circuit, Parallel - Arrangement of electrical devices in which the cur­rent divides and travels through two or more paths.

Circuit, Pilot -  Secondary circuit used to control a device in the main circuit.

Circuit, Series -  Electrical path in which elec­tricity to operate second lamp or device must pass through first; cur­rent flow travels, in turn, through all devices connected together.

Circuit Breaker - Safety device, which automatically opens an electrical circuit if overloaded.

Closed Circuit - Electrical circuit in which electrons are flowing.

Closed Loop - Any piping system where the internal fluids are sealed from their surroundings. Commonly  referred to as glycol loops 

Clutch, Magnetic -  Clutch built into automobile compressor flywheel, operated magnetically, which allows pulley to revolve without driving compressor .

Coefficient of Conductivity - Measure of the relative rate at which different materials conduct heat.

Coefficient of Expansion - Increase in unit length, area, or volume for one degree rise in temperature.

Coefficient of Performance (COP) - System capacity divided by electrical energy consumed.

Cogeneration - Primary source of energy that is also used to produce a secondary source of energy.

Cold - The absence of heat.

Cold Storage - The process of preserving perishable items on a large scale.

Cold Wall - Refrigerator construction which has the refrigerator serving as the cooling surface.

Colloids - Miniature cells peculiar to meats, fish, and poultry which disrupted, cause food to become rancid. Low temperatures minimize this action.

Combustible Liquids - Liquid having a flash point at or above 140^oF

Comfort Chart - A psychometric chart for the propose of showing effective temperatures.

Comfort Zone -  Area on psychometric chart which shows condition of temperature, humidity in which  people are comfortable.

Compound Compressor- A compressor with one ore more head.

Compound Gauge - Instrument for measuring pressure both above and below atmospheric pressure.

Compound Refrigerating Systems - System, which has several compressors or compressor cylinders in series.

Compression - Term used to denote increase of pressure on a fluid using mechanical energy.

Compression Gauge -  An instrument used to measure positive pressure.

Compressor -  A refrigeration component that make a pressure difference in the system witch causes refrigerant to flow.

Compressor Reciprocating - Compressor which uses a piss cylinder mechanism to provide pumping action.

Compressor, Rotary - Compressor which uses vanes, a mechanisms, or other rotating devices to provide pumping action.

Condensate - A fluid formed when a gas is cooled .

Condensation -  Liquid or droplets which form when a gas or cooled below its dew point.

Condense - The changing of a gas or vapor to a liquid.

Condenser - The heat rejection component of a system  where the refrigerant is condensed from a vapor to liquid. 

Condenser, Air Cooled - Heat exchanger that transfers heat to the surrounding air.

Condenser, Water Cooled - Heat exchanger that transfers heat to water.

Condense Comb - Comb-like device used to straighten the metal fins on condensers or evaporators.

Condenser Fan - A fan used to move air through air-cooled condenser.

Condensing Furnace - A high efficiency furnace that also removes latent heat form the combustion products.

Condensing Pressure - See head pressure

Condensing temperature – the temperature at witch a substance will condense.

Condensing unit - Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser, and returns it to the metering device.

Conductor - Substance or body capable of transmitting electricity or heat.

Constrictor - Tube or orifice used to restrict flow of a gas or a liquid.

Contaminant - Substance such as dirt, moisture, or other matter foreign to refrigerant or refrigerant oil in system.

Control - any device to to start stop regulate or protect a system.

Control, Low Pressure -  a Safety device connected to low-pressure side of system.

Control, Refrigerant -  A device used to regulate flow of liquid refrigerant into evaporator.

Control, Temperature - Temperature-operated thermostatic device which automatically opens or closes a circuit.

Control System - All of the components required for the automatic control of a process variable.

Control Valve - Valve which regulates the flow or pressure of a medium which affects a controlled process.

Controller - A group of controls and circuits used to accurately and automatically operate a device.

Convection - Transfer of heat from one point to another by means of gravity.

Convection, Forced - Transfer of heat resulting from forced move­ment of liquid or gas by means of a fan or pump.

Convection, Natural - Circulation of a gas or liquid due to difference in density resulting from temperature differences.

Cooler - Heat exchanger which removes heat from a substance.

Cooling Tower - Device which cools by water evaporation in air

Copper Plating - Abnormal condition developing in some units in which copper is electrolytically deposited on some compressor surfaces.

Core, Air - Coil of wire not having a metal core.

Core, Magnetic - Magnetic center of a magnetic field.

Corrosion - Deterioration of materials from chemical action.

Coulomb - The quantity of electricity transferred by an electric current of one ampere in one second.

Counter EMF - Tendency for reverse electrical flow as magnetic field changes in an induction coil.

Counter Flow -Flow in opposite direction.

Couplings - Mechanical device joining refrigerant lines.

Crankshaft Seal -  Leak proof joint between crankshaft and compressor body.

Crisper - Drawer or compartment in refrigerator designed to provide high humidity along with low temperature to keep vegetables especially leafy vegetables-cold and crisp.

Critical Pressure - Compressed condition of refrigerant, which gives liquid and gas the same properties.

Critical Temperature - Temperature at which vapor and liquid have same properties.

Critical Vibration - Vibration which is noticeable and harmful to structure.

Cross Charged- Two fluids which together create a desired pressure-temperature properties.

Cryogenics -Refrigeration which deals with producing temperatures of 250⁰F below zero and lower.

Current - the flow of electrons through a conductor.

Current Relay - Device which opens or closes a circuit upon a change in current flow.

Cut –In - The value at which the con­trol circuit closes.

Cut-Out - The value at which the control cir­cuit opens.

Cycle - Series of events or operations which have tendency to repeat in the same order.

Cylinder, Refrigerant - A cylinder used to store refrigerant.

Cylinder Head - Plate or cap which encloses compression end of com­pressor cylinder.