2,400+ Definitions

HVAC GLOSSARY

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

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Cross Flow Heat Exchanger
A cross flow heat exchanger has fluids moving perpendicular to…
Crossflow Tower
A crossflow cooling tower directs air horizontally across falling water…
CSA C22.2
CSA C22.2 is the Canadian safety standard series for electrical…
Curb
A curb is a structural frame or raised base that…
Cv Value
The Cv value is a numerical coefficient that quantifies the…
Cx Authority
The Cx Authority is the designated individual or firm responsible…
Damper Actuator
A damper actuator is an electromechanical or pneumatic device that…
Darcy Weisbach
The Darcy-Weisbach equation is a theoretical formula calculating pressure drop…
Data Center ASHRAE Classes
ASHRAE classes categorize data center environments based on allowable temperature,…
Data Center Cooling
Data Center Cooling encompasses the specialized HVAC systems, strategies, and…
Data Center Cooling Infrastructure
Data center cooling infrastructure removes heat generated by thousands of…
Data Logger
A data logger is an electronic device that automatically records…
Data Logging
Data logging is the automated collection and storage of system…
Daylighting
Daylighting is the strategic use of natural sunlight through windows,…
DC Coupled Storage
DC coupled storage systems connect batteries directly to solar panels…
DC Power
DC power, or direct current power, is electrical energy that…
Decommissioning
Decommissioning in HVAC refers to the formal, systematic process of…
Dedicated Outdoor Air System
A Dedicated Outdoor Air System (DOAS) is an HVAC configuration…
Deep Energy Retrofit
A Deep Energy Retrofit (DER) is a comprehensive building renovation…
Deep Vacuum
Deep vacuum is an HVAC refrigeration procedure that removes moisture…
Defrost Board
A defrost board is an electronic control module installed in…
Defrost Control
Defrost control is a system integrated into heat pumps that…
Defrost Heater
A defrost heater is an electrical resistance heating element installed…
Defrost Termination Switch
A defrost termination switch (DTS) is a temperature-sensing device, typically…
Defrost Timer
A defrost timer is an electromechanical or electronic control device…
Dehumidifier
A dehumidifier removes excess moisture from indoor air, reducing relative…
Delta T
Delta T (ΔT) is the temperature difference between supply and…
Delta T Cooling
Delta T (ΔT) cooling measures the temperature difference between return…
Demand Charge
A demand charge is a fee assessed by utilities based…
Demand Controlled Ventilation
Demand Controlled Ventilation (DCV) automatically adjusts outdoor air intake based…
Demand Factor
Demand factor is the ratio of actual simultaneous demand to…
Demand Flexibility
Demand Flexibility refers to the capability of HVAC systems and…
Demand Limiting
Demand Limiting is an HVAC control strategy that automatically reduces…
Demand Response
Demand response programs allow HVAC systems and building operators to…
Demand Side Management
Demand Side Management (DSM) encompasses utility programs and strategies that…
Depth of Discharge
Depth of Discharge (DoD) is the percentage of a battery’s…
Derivative Control
Derivative control responds to the rate of change of temperature…
Desiccant Cooling
Desiccant cooling is a dehumidification process that uses moisture-absorbing materials…
Desiccant Wheel
A desiccant wheel is a rotating cylindrical device packed with…
Design Conditions
Design conditions are standardized outdoor temperature, humidity, and weather parameters…
Design Day
A design day is a synthetic 24-hour weather profile representing…
Design Development
Design Development expands upon schematic designs by adding greater detail,…
Dew Point
Dew point is the temperature at which air becomes saturated…
Dew Point Temperature
Dew point temperature is the temperature at which air becomes…
Digital Manifold
A digital manifold is an electronic pressure and temperature measurement…
Digital Manometer
A digital manometer is an electronic pressure measurement device that…
Digital Refrigerant Scale
A digital refrigerant scale is a precision electronic weighing device…
Dilution Ventilation
Dilution ventilation, or general ventilation, introduces fresh outdoor air throughout…