2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
DX Coil
A DX coil, or direct expansion coil, is a cooling…
Dynamic Braking Resistor
A power resistor connected across the DC bus of a…
Dynamic Glass
Dynamic glass is responsive glazing technology that automatically adjusts light…
Earth Energy System
A geothermal heat pump installation that uses the relatively stable…
ECM
An ECM, or electronically commutated motor, is a brushless direct-current…
ECM Circulator
A hydronic pump driven by an electronically commutated motor that…
ECM Motor
An electronically commutated motor (ECM) is a high-efficiency brushless DC…
Economizer
An economizer is a control system that uses outdoor air…
Economizer Balance Point
The outdoor temperature calculated based on current electricity and fuel…
Economizer Coil
An economizer coil is a heat recovery device that uses…
Economizer Cycle (Refrigeration)
A refrigeration circuit enhancement that uses a flash tank or…
Economizer Enthalpy Control
An air-side economizer control method that compares the total heat…
Economizer Mode
Economizer Mode is an HVAC control strategy that uses outdoor…
EER
EER (Energy Efficiency Ratio) measures an air conditioner or heat…
EER2
EER2 (Energy Efficiency Ratio 2) is a seasonal energy efficiency…
EEV
An Electronic Expansion Valve (EEV) is a precision metering device…
Effective Leakage Area
A single equivalent hole size, expressed in square inches or…
Effective Length
The equivalent straight duct length assigned to a fitting that…
Electric Actuator
An electric actuator uses AC or DC electrical power to…
Electric Bill Analysis
Electric bill analysis involves reviewing utility invoices to identify usage…
Electric Furnace
An electric furnace is a heating appliance that uses electrical…
Electric Grid
The electric grid is the interconnected network of power generation…
Electric Heating Coil
An electric heating coil is a resistance heating element that…
Electric Rate Structure
Electric rate structure defines how utilities calculate charges based on…
Electric Water Heater
An electric water heater uses electrical resistance heating elements to…
Electrical Conduit
Electrical conduit is a protective tube or raceway that houses…
Electrical Connection Check
An electrical connection check verifies that all power terminals, wiring…
Electrical Grounding
Electrical grounding is the connection of electrical systems and equipment…
Electrical Inspection
An electrical inspection is a thorough examination of electrical systems,…
Electrical IR Scan
Electrical IR scans use thermal imaging to detect abnormal heat…
Electrical Panel
An electrical panel, also called a breaker box or distribution…
Electrical Permit
An electrical permit is an official authorization issued by local…
Electrical Raceway
An electrical raceway is any channel, duct, or enclosed pathway…
Electrical Troubleshooting
Electrical troubleshooting is the systematic process of diagnosing electrical failures…
Electrification
Electrification is the process of converting HVAC systems from fossil…
Electrochromic Glass
Electrochromic glass, also called smart glass, is a dynamic glazing…
Electronic Air Cleaner
Electronic air cleaners use electrostatic charging and collection plates to…
Electronic Expansion Valve
An Electronic Expansion Valve (EEV) is a precision metering device…
Electronic Leak Detector
An electronic leak detector is a handheld instrument that senses…
Electronic Overload Relay
A solid-state protective device that monitors motor current and provides…
Electronic Superheat Calculator
A handheld or manifold-integrated device that takes suction pressure and…
Electronic Thermometer
A temperature-measuring instrument using a thermocouple or thermistor probe to…
Electronically Commutated Motor
A brushless DC motor that uses permanent magnets in the…
Electrostatic Filter
Electrostatic filters use self-generating electric charges in the filter fibers…
Electrostatic Precipitator
Electrostatic precipitators remove particles down to 0.01 microns using high-voltage…
Elevation Difference
The vertical height difference between the outdoor unit and indoor…
Emergency Demand Response
Emergency Demand Response is a rapid reduction of electrical loads…
Emergency Ventilation
Emergency ventilation is a rapid air exchange system designed to…