2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
System Curve
A graphical representation of the relationship between flow rate and…
System Curve Fan
A system curve is a graph representing the static pressure…
System Decommissioning
System decommissioning in HVAC refers to the planned, systematic process…
System Diagnosis
System diagnosis is the systematic evaluation of HVAC equipment performance…
System Flush
A system flush is the process of circulating a specialized…
System Selection
System Selection is the decision-making process for choosing the overall…
System Startup Checklist
A system startup checklist is a documented procedure verifying all…
System Ventilation Efficiency
A multiplier used in ASHRAE 62.1 multiple-zone recirculating system calculations…
System Weigh In
System Weigh In is a comprehensive verification process performed on…
Systems Manual
A Systems Manual is a comprehensive reference document that contains…
T S Diagram
A T-S (Temperature-Entropy) diagram is a thermodynamic chart that plots…
TAB Report
A TAB report is the formal documentation of airflow measurements,…
Tank Water Heater
A tank water heater stores heated water in an insulated…
Tankless Crossover
Tankless crossover is a plumbing configuration issue where hot water…
Tankless Water Heater
A tankless water heater heats water on demand without storage,…
Tankless Water Heater Flow Rate
Tankless water heater flow rate is the volume of water…
Tankless Water Heater GPM
Tankless water heater GPM (gallons per minute) rating specifies the…
Tape Lift Sample
Tape lift sampling is a quick, non-invasive method that uses…
Task-Ambient Conditioning
An HVAC strategy that provides minimal background conditioning to the…
Technician Certification
Technician Certification, mandated by EPA Section 608, is the professional…
TEFC Motor
TEFC (Totally Enclosed Fan-Cooled) Motor is a sealed motor design…
Temperature
Temperature is a fundamental physical property of matter that quantitatively…
Temperature Coefficient
Temperature coefficient quantifies how photovoltaic module performance changes with each…
Temperature Data Logger
A temperature data logger continuously records ambient or system temperatures…
Temperature Entropy Diagram
A temperature-entropy (T-S) diagram plots refrigerant properties with absolute temperature…
temperature glide
The difference in temperature between the dew point and bubble…
Temperature Pressure Relief Valve
A Temperature Pressure Relief (TPR) valve is a critical safety…
Temperature Rise Check
A temperature rise check measures the difference between return air…
Temperature Sensor
A temperature sensor is a device that detects and measures…
Temperature Split
Temperature split is the difference between return air temperature and…
Terminal Unit
A terminal unit is an HVAC component installed at or…
Test Adjust Balance
Test Adjust Balance (TAB) is the systematic process of measuring,…
TEWI
TEWI, or Total Equivalent Warming Impact, is a comprehensive metric…
Thermal Break
A thermal break is a low-conductivity material inserted between thermally…
Thermal Bridge
A thermal bridge is a pathway through insulation where heat…
Thermal Bridging
A condition where a highly conductive material, such as a…
Thermal Comfort
Thermal comfort is the condition of mind that expresses satisfaction…
Thermal Conductivity
Thermal conductivity is a material’s ability to conduct heat through…
Thermal Conductivity of Soil
A soil property expressing how readily heat moves through the…
Thermal Cutout
A thermal cutout is a non-resettable safety device that permanently…
Thermal Efficiency
The ratio of useful heat delivered to the heating medium…
Thermal Efficiency of a Heat Pump
A broader performance measure comparing total useful thermal output to…
Thermal Energy Storage (TES)
A system that produces and stores chilled water or ice…
Thermal Envelope
The thermal envelope is the boundary consisting of all building…
Thermal Expansion
Thermal expansion is the increase in water volume that occurs…
Thermal Formation Testing
An in-situ field measurement procedure that circulates fluid through a…
Thermal Imaging Camera
An instrument that produces a visual image representing temperature distribution…
Thermal Imaging Inspection
Thermal imaging inspection uses specialized cameras to detect temperature variations…