2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Solid Desiccant
Solid desiccant materials are porous minerals or composite substances that…
Sorption Isotherm
A curve relating the equilibrium moisture content of a hygroscopic…
Sound Attenuator
A sound attenuator is a lined duct section or silencer…
Sound Baffle
A sound baffle is an engineered acoustic element designed to…
Sound Level Meter
A sound level meter is a calibrated electronic instrument that…
Source Control
Source control eliminates or reduces indoor air pollutants at their…
Source Energy
Source Energy represents the total raw energy consumed at power…
Specific Enthalpy
The enthalpy of moist air referenced to a unit mass…
Specific Heat
Specific heat is the amount of thermal energy required to…
Specific Leakage Rate
Air leakage expressed as cubic feet per minute per square…
Specific Volume
Specific volume is the volume occupied by one pound of…
Spiral Duct
Spiral duct is a round ductwork constructed by spirally winding…
Split System
A split system is an HVAC configuration that divides its…
Split System Installation
Split system installation involves connecting an outdoor condenser unit to…
Splitter Damper
A curved or flat blade installed at the junction of…
Spore Trap
A spore trap is a passive or active air sampling…
Spot Exhaust
Spot exhaust is a localized ventilation system that removes moisture,…
Spot Monitoring
Spot monitoring is the collection of air quality measurements at…
Spray Foam Insulation
Spray foam insulation is a polyurethane or polyisocyanurate material applied…
Spring Isolator
A spring isolator is a mechanical device using compressed steel…
Spring Return Actuator
A spring return actuator uses an internal spring mechanism to…
Spring Startup
Spring Startup is the pre-season service performed before cooling season…
SREC
An SREC (Solar Renewable Energy Certificate) is a tradable credit…
Stack Effect
The stack effect describes the natural movement of air through…
Stack Effect Pressure
The pressure difference across a building envelope driven by the…
Stack Temperature
The temperature of flue gases measured at the appliance flue…
Stainless Steel Pipe
Stainless steel pipe is a corrosion-resistant tubing made from steel…
Standby Mode
Standby Mode is a low-energy operational state where HVAC components…
Standing Column Well
A geothermal open-loop variant that draws water from and returns…
Standing Pilot
A standing pilot is a small, continuously burning flame that…
Standing Pressure Test
A standing pressure test is a procedure used to verify…
Standing Vacuum Test
An extended period, often 15 to 30 minutes or more,…
Staple-Up Radiant
A radiant floor heating installation method where PEX or other…
Start Assist
A start assist is an auxiliary electrical device installed in…
Start Capacitor
An electrolytic capacitor connected in series with the start winding…
State Energy Office
A State Energy Office is the designated state agency responsible…
State of Charge
State of Charge (SoC) is the current amount of energy…
Static Pressure
Static pressure is the force exerted by air against duct…
Static Pressure Check
A static pressure check measures ductwork resistance to airflow, helping…
Static Pressure Test
A static pressure test measures the resistance to airflow within…
Static Regain
The increase in static pressure that occurs when air velocity…
Steady State
Steady state occurs when system properties remain constant over time,…
Steam Boiler
A steam boiler is a closed pressure vessel designed to…
Steam Coil
A steam coil is a heating heat exchanger that transfers…
Steam Plant
A Steam Plant is a centralized heating facility that generates…
Step Down Transformer
A step down transformer reduces high voltage electrical power to…
Step Up Transformer
A step-up transformer increases voltage while proportionally decreasing current, maintaining…
Stoichiometric Combustion
The theoretical ideal condition in which exactly the right amount…