2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
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 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 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 Cutout
A thermal cutout is a non-resettable safety device that permanently…
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 Imaging Inspection
Thermal imaging inspection uses specialized cameras to detect temperature variations…
Thermal Mass
Thermal mass is a building material’s capacity to absorb and…
Thermal Mass Effect
The thermal mass effect describes the ability of building materials…
Thermal Resistance
Thermal resistance, expressed as R-value, measures a material’s ability to…
Thermal Storage
Thermal storage is a system that captures and retains thermal…
Thermistor
A thermistor is a temperature-sensitive resistor that changes electrical resistance…
Thermocouple
A thermocouple is a temperature-sensing device that generates a small…
Thermocouple Meter
A thermocouple meter measures temperature using thermocouple probes, which generate…
Thermodynamic System
A thermodynamic system is a defined region of matter or…
Thermodynamics
Thermodynamics is the branch of physics that deals with the…
Thermoelectric Cooling
Thermoelectric cooling uses electrical current flowing through semiconductor materials to…
Thermopile
A thermopile is a series of thermocouples connected in sequence…
Thermosiphon Heat Recovery
Thermosiphon heat recovery uses natural convection to circulate a heat…
Thermosiphon System
A thermosiphon system is a passive solar water heating method…
Thermostat
A thermostat is the control device that monitors indoor temperature…
Thermostat Calibration
Thermostat calibration adjusts the internal temperature sensor so that displayed…
Thermostat Installation
Thermostat installation is the process of mounting a temperature control…
Thermostat Wiring
Thermostat wiring connects low-voltage control circuits between the thermostat, furnace,…
Thermostatic Expansion Valve
A thermostatic expansion valve (TXV) is a precision refrigerant metering…
Thin Film Solar Panel
A thin film solar panel uses ultra-thin semiconductor layers (1-2…