Eddy Currents - Induced currents flowing in a core. 

EER - See ENERGY EFFICIENCY RATIO. 

Effective Area - Actual flow area of an air inlet or outlet. 

Effective Temperature - Overall effect on a human of air temperature, humidity, and air movement. 

Efficiency -  Output of a device, system, or activity, divided by the in­put necessary to create the output. 

Ejector -  A device which uses high fluid velocity, such as a venturi, to create low pressure or vacuum at its throat to draw in fluid from another source.

Electric Defrosting - Use of electric resistance heating coils to melt ice off evaporators. 

Electric Heating – Heating using electric resistance heaters. 

Electrodepositing Process - Process in which metallic particles are applied to another metal surface through the use of an electric current.

Electrolysis - Movement of electricity through a substance which causes a chemical change in the substance or its container.

Electromagnet – A coil of wire wrapped an iron core. When electric current flows through wire, the assembly becomes a magnet.

Electromagnetic Energy - Energy that has both electrical and magnetic characteristics.

Electron - The portion of an atom that carries a negative charge.

Electronic Control Diagnostics - Trouble codes that may be referenced on an automatic climate control system to diagnose problems.

Electronic Leak Detector – A electronic instrument that measures electronic flow across gas gap. Electronic flow changes indicate presence of refrigerant gas molecules.

Electronic Relay – A relay that is mounted on a circuit board and is controlled by a electronic signal , such as a triac, 

Electronic Sight Glass – A electronic device that detects the presence of vapor in the liquid. 

Electronic Thermistor – A temperature sensitive resistor used on electronic thermostats. 

Electronic Thermostat – A thermostat that uses electronic components to accomplish various sensing, switching, timing, staging,and display functions. 

Electronics - Field of science dealing with electron devices and their uses. 

Electrostatic Filter - A filter for cleaning air that utilizes electricity to attract dust particles to electrically charged plates. 

End Bell – the plates on the ends of a electric motor which usually holds motor bearings. 

End Play - The movement of the motors shaft along its centerline. 

Endothermal - Chemical reaction in which heat is absorbed. 

Energy - The ability to do work. 

Energy Audit -   To accurately determining the current energy consumption for a given area. 

Energy conservation – To look for, determine and institute changes that will conserve energy.

Energy Efficiency Ratio (EER) - Cooling capacity in BTU/hr divided by electrical energy consumed in watts.

Energy Management Control System - A system that optimizes total energy usage in a building.

Energy Utilization Index (EUI) - A number which is used to com­pare energy usages for different areas. It is calculated by dividing the energy consumption (in Btus) by the square footage of the condition­ed area.

Enthalpy - Total amount of heat in one pound of a substance.Entropy - Mathematical factor used in engineering calculations. Energy in a system.

Environment - The surrounding conditions.

Enzyme - Organic substance, that speeds up chemical changes in foods. 

Eutectic - That certain mixture of two substances providing lowest melting temperature of all the various mixes of the two substances.

Eutectic Point - Freezing temperature for eutectic solutions. 

Evacuation – The removal of contaminants in a refrigeration system.

Evaporator - The heat absorption component of a system  where the refrigerant is evaporated from a liquid to a vapor. 

Evaporator, Dry Type - Evaporator in which the refrigerant is in the liquid droplet form. 

Evaporator, Flooded - Evaporator containing liquid refrigerant at all times. 

Evaporator Fan - A mechanical device that increases airflow over the heat exchange surface of evaporators.

Evaporative Condenser - is one that utilizes the evaporation of water by air at the condenser surface as a means of heat dissipation.

Evaporation - Is the change of state from a liquid to a vapour.

EWT - Entering water or fluid temperature.

Exfiltration - Slow flow of air from the building to the outdoors.

Exhaust Port - That opening which carries the fluid to the downstream pressure of a fluid system.

Exhaust Valve -A movable port which provides an outlet for the cylinder gases in a compressor. 

Exothermal - A chemical reaction in which heat is released.

Expansion Joint - A device designed to allow movement caused by expansion and contraction.

Expansion Valve – Is one type of metering device in refrigerating system, which reduces the pressure from the high side to the low side and is operated by pressure.

 Expendable Refrigerant System – A system which discards the refrigerant after it has evaporated.

 External Drive - A Term used to indicate a compressor driven directly from the shaft or by a belt using an external motor.

 External Equalizer - Tube connected to the outlet of the evaporator to allow the diaphragm of the thermostatic expansion valve to disregard any pressure drop in the evaporator.