2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Safety Switch Test
A safety switch test verifies that automatic shutoff devices function…
Saturation Pressure
Saturation pressure is the pressure at which a gas condenses…
Saturation Temperature
Saturation temperature is the temperature at which air becomes 100%…
SCADA System
SCADA (Supervisory Control and Data Acquisition) is an industrial control…
Schematic Design
Schematic Design is the initial phase of architectural planning where…
Schematic Diagram
A schematic diagram is a simplified, symbolic representation of an…
Schrader Valve
A Schrader valve is a spring-loaded poppet valve designed to…
Scope 1 Emissions
Scope 1 Emissions are direct greenhouse gas emissions produced from…
Scope 2 Emissions
Scope 2 Emissions are indirect greenhouse gas emissions generated by…
Screw Chiller
A screw chiller is a vapor-compression refrigeration system that uses…
Scroll Chiller
A scroll chiller is a vapor-compression refrigeration system that uses…
Scroll Compressor
A scroll compressor uses two interleaved spiral-shaped scrolls to compress…
SDHW
SDHW is the abbreviation for Solar Domestic Hot Water, representing…
Sealed Combustion Furnace
A sealed combustion furnace draws all combustion air directly from…
Seasonal COP
Seasonal COP (SCOP) is the ratio of total heating energy…
Seasonal Efficiency Standard
Seasonal Efficiency Standards measure HVAC equipment performance across an entire…
Seasonal Energy Efficiency Ratio
Seasonal Energy Efficiency Ratio (SEER) is a performance metric that…
Seasonal Energy Efficiency Ratio (SEER)
SEER (Seasonal Energy Efficiency Ratio) was the primary efficiency rating…
Seasonal Total Equivalent Warming Impact
Seasonal Total Equivalent Warming Impact (STEWI) is a comprehensive environmental…
Second Law of Thermodynamics
The Second Law of Thermodynamics states that entropy in an…
Secondary Heat Exchanger
A secondary heat exchanger is an additional metal component in…
Secondary Refrigerant
A secondary refrigerant is a heat transfer fluid that carries…
Section 25C Tax Credit
Section 25C (formerly known as the Residential Energy Credits) provides…
Section 410
Section 410 of the Clean Air Act addresses stationary refrigeration…
Section 48 ITC
Section 48 of the Internal Revenue Code provides a federal…
Section 608
Section 608, part of the Clean Air Act, is the…
Section 609
Section 609 of the Clean Air Act regulates the servicing…
Sediment Buildup
Sediment buildup refers to the accumulation of minerals, scale, and…
SEER
SEER (Seasonal Energy Efficiency Ratio) is a standardized measurement rating…
SEER2
Seasonal Energy Efficiency Ratio 2 (SEER2) is the updated federal…
Seismic Restraint
A seismic restraint is a cable, strap, or bracing system…
Sensible Heat
Sensible heat is the energy required to change the temperature…
Sensible Heat Ratio
Sensible Heat Ratio (SHR) is the proportion of cooling capacity…
Sensible Heat Wheel
A sensible heat wheel is a rotating heat recovery device…
Sensor Calibration
Sensor calibration is the process of adjusting HVAC sensors to…
Sequence of Operations
A Sequence of Operations is a detailed written description of…
Sequencer
A sequencer is an automatic control device that stages the…
Series Fan Powered Box
A Series Fan Powered Box is a type of variable…
Service Agreement
A service agreement is a comprehensive contract defining the scope…
Service Call
A service call is a technician visit to a customer’s…
Service Clearance
Service clearance is the dedicated space required around HVAC equipment…
Service Report
A service report documents all work performed during an HVAC…
Service Valve
A service valve is a manually operated valve installed on…
Setpoint
A setpoint is the target temperature that an HVAC system…
Setpoint Reset
Setpoint reset automatically adjusts the temperature or pressure target based…
Sheet Metal Work
Sheet metal work encompasses the cutting, forming, and joining of…
Shell and Tube Heat Exchanger
A shell and tube heat exchanger transfers heat between two…
Shop Drawing
A shop drawing is a detailed construction document prepared by…