2,400+ Definitions

HVAC GLOSSARY

Every HVAC term, acronym, and industry phrase — defined in plain English.

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Airflow Balancing
Airflow balancing adjusts dampers and registers throughout a duct system…
Airflow Check Annual
An annual airflow check verifies that the heating and cooling…
Airflow Measurement
Airflow measurement quantifies the volume of air moving through an…
Airflow Problem
An airflow problem occurs when insufficient air moves through the…
Airside Economizer Lockout
A control function that disables the airside economizer when outdoor…
Alarm Management
Alarm management is the systematic configuration, filtering, notification, and response…
Alexa HVAC
Alexa HVAC refers to heating and cooling systems compatible with…
Algae Treatment
Algae treatment applies biocidal chemicals to condensate pans and drain…
Allergen
An allergen is a substance capable of triggering an adverse…
Alternating Current
Alternating current (AC) is electrical current that periodically reverses direction,…
American Innovation Manufacturing Act
The American Innovation Manufacturing (AIM) Act is comprehensive federal legislation…
AMI
AMI is the abbreviation for Advanced Metering Infrastructure, an integrated…
Ammonia Absorption Chiller
An ammonia absorption chiller uses aqueous ammonia solution as the…
Amp Draw
Amp draw is the electrical current in amperes that a…
Ampere
An ampere (A), also called amp, is the unit of…
Anemometer
An anemometer is an instrument that measures air velocity and…
Annual Energy Use
Annual Energy Use is the total amount of energy consumed…
Annual Fuel Utilization Efficiency
Annual Fuel Utilization Efficiency (AFUE) is a metric that expresses…
Annual HVAC Maintenance
Annual HVAC Maintenance is a comprehensive service performed once yearly…
Annualized Fuel Utilization Efficiency
Annualized Fuel Utilization Efficiency (AFUE) is a metric that expresses…
Ansul System
An Ansul System is an automatic fire suppression system specifically…
Anti Islanding
Anti-islanding is a safety feature in grid-connected photovoltaic systems that…
Anti-Condensate Glass
Refrigerated display case door glass fabricated with multiple panes and…
Anti-Sweat Heater
An electric resistance heater embedded in or attached to door…
Anti-Windup
A software technique applied to PID controllers that limits or…
Antifreeze Solution
A mixture of water and a freezing point depressant such…
Apparatus Dew Point
The effective surface temperature of a cooling coil at which…
Apparent Power
Apparent power is the total electrical power supplied to an…
Appendix G
Appendix G is the section of ASHRAE 90.1 that establishes…
Apple HomeKit HVAC
Apple HomeKit HVAC enables control of compatible heating and cooling…
Application Controller
A programmable DDC controller designed to execute custom or application-specific…
Applied Chiller
An applied chiller is a large-capacity, custom-engineered chilling system designed…
Approach Temperature
Approach temperature is the difference in degrees Fahrenheit between the…
Approach Temperature Method
The Approach Temperature Method is a performance evaluation technique used…
Approach Temperature Tower
Approach temperature is the difference between the cooled water leaving…
Aquastat
An aquastat is a temperature-sensitive control device designed to measure…
Arc Fault Circuit Interrupter
An Arc Fault Circuit Interrupter (AFCI) is a protective device…
ARI
ARI is the Air-Conditioning and Refrigeration Institute, the predecessor organization…
ARI 210
Legacy Air-Conditioning and Refrigeration Institute standard, predecessor to AHRI 210/240,…
ASHRAE
ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) is…
ASHRAE 103
ASHRAE standard specifying the test method for measuring the annual…
ASHRAE 135
ASHRAE 135 defines BACnet, an open protocol standard for building…
ASHRAE 15
Definition ASHRAE 15 is the Safety Standard for Refrigeration Systems…
ASHRAE 15 Safety Standard
ASHRAE 15 is the primary safety standard for refrigerant classification…
ASHRAE 189.1
ASHRAE 189.1, officially titled Standard for the Design of High-Performance…
ASHRAE 34
Definition ASHRAE 34 is the Designation and Safety Classification of…
ASHRAE 52.2
Definition ASHRAE 52.2 is the Method of Testing General Ventilation…
ASHRAE 55
ASHRAE 55 is a standard that defines thermal comfort conditions…