2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
Selectivity Index
The ratio of a glazing’s visible transmittance to its solar…
Sensible Heat
Sensible heat is the energy required to change the temperature…
Sensible Heat Gain
The portion of the total cooling load that raises the…
Sensible Heat Ratio
Sensible Heat Ratio (SHR) is the proportion of cooling capacity…
Sensible Heat Recovery Efficiency
The ratio of sensible heat actually transferred by a heat…
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…
Shaded Pole Motor
A simple single-phase induction motor that uses a short-circuited copper…
Shaft Grounding Ring
A device mounted on the motor shaft that uses conductive…
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…
Short Circuit Current
Short circuit current (SCC) is the maximum current a photovoltaic…
Short Cycling
Short cycling occurs when a compressor starts and stops at…
Shut Off Valve
A shut off valve is a device that stops water…
Sick Building Syndrome
Sick Building Syndrome (SBS) describes a cluster of health symptoms…
Sidearm Water Heater
A sidearm water heater is a compact, tankless heat exchanger…
Sight Glass
A sight glass is a transparent viewing port installed in…
Significant New Alternatives Policy
The Significant New Alternatives Policy is the EPA’s comprehensive regulatory…
Silver Brazing Alloy
A filler metal containing silver (commonly 0 to 56 percent)…
Single Axis Tracker
Single axis trackers rotate photovoltaic panels along one axis, typically…
Single Line Diagram
A Single Line Diagram is a simplified schematic representation of…
Single Phase
Single-phase power is an alternating current system with one active…
Single Stage Furnace
A single stage furnace is a heating system designed to…
Single Zone Unit
A single zone unit is a heating, ventilation, and air…
Single-Zone Mini-Split
A ductless system consisting of exactly one outdoor unit connected…
Site Energy
Site Energy is the total amount of energy delivered to…
Slab-on-Grade Radiant
A radiant heating system in which tubing is embedded in…
Slim Duct Indoor Unit
A low-profile ducted air handler designed for installation in shallow…
Sling Psychrometer
A hand-held psychrometer mounted on a swivel handle that is…
Slinky Loop
A horizontal geothermal loop configuration where the pipe is coiled…
Slot Diffuser
A slot diffuser is a linear air distribution device featuring…
Slugging
Slugging occurs when large volumes of liquid refrigerant unexpectedly enter…
SMACNA
SMACNA (Sheet Metal and Air Conditioning Contractors’ National Association) establishes…