Efficiency Heating & Cooling Portland OR locally owned HVAC
Portland family owned HVAC company

HVAC Glossary

Absorption Chiller

An Absorption Chiller uses heat, rather than mechanical energy, to drive the refrigeration cycle.

Air Balance

Air Balance involves adjusting an HVAC system to ensure even distribution of air throughout a facility.

Air Conditioner (AC)

A device that removes heat and humidity from indoor air to cool a space.

Air Handler

A unit that circulates and conditions air as part of an HVAC system.

Air Quality

A measure of the cleanliness and healthiness of the air within a specific environment.


The movement of air through a space, driven by HVAC equipment.

Ambient Air

The air surrounding an environment, typically outside air used for ventilation.

Antibacterial Filter

A filter designed to remove bacteria and other microorganisms from the air.

Balanced Airflow

An air distribution system that equally distributes air across all zones.


A fan component in an HVAC system that moves air through ducts.

Bypass Damper

A damper used to control air flow without passing through the main air handler.


The maximum output or effectiveness an HVAC unit can provide.

CFM (Cubic Feet per Minute)

A measurement of air volume flow rate indicating how much air can move in a minute.

Chemical Cleaning

The process of using chemical agents to clean HVAC components and systems.


Machines that remove heat from a liquid via a vapor-compression or absorption cycle.


A component in HVAC systems where heat transfer occurs.


The liquid byproduct of the air cooling and dehumidification process.

Condensation Drain Line

A pipe that directs condensation away from an HVAC unit.

Condenser Fan

A fan in the condenser unit that helps expel heat to the outdoors.

Controlled Environment

An area where the temperature, humidity, and air quality are regulated.


A movable plate in ductwork that regulates or stops air flow.


The process of removing moisture from the air.


A device that removes excess moisture from the air to control humidity levels.

Ductless Mini-Split System

A small-scale air conditioning system that does not require ductwork.

EER (Energy Efficiency Ratio)

A rating that denotes how effectively an air conditioner uses energy.

Evaporative Cooler

A cooling device that uses the evaporation of water to reduce air temperature.

Expansion Valve

A valve that reduces the pressure of refrigerant, allowing it to absorb heat from the environment.

Fan Coil Unit

A simple device consisting of a fan and a heating or cooling coil, used in HVAC systems.


A device used to remove particles and contaminants from air or liquids.

Freon Leak

A release of Freon gas from an air conditioning system, often due to a malfunction.

Heat Exchanger

A system that transfers heat between two or more fluids without mixing them.

Heat Load

The amount of heating or cooling needed to maintain desired temperatures in a space.

Heat Pump

A device that transfers heat energy from a source to a heat sink using refrigeration.

HEPA Filter

A high-efficiency air filter that captures fine particles such as dust and allergens.


A device that adds moisture to the air to prevent dry conditions.

IAQ (Indoor Air Quality)

The quality of the air inside buildings, measured by the presence of pollutants and toxins.

Inverter Technology

Advanced technology in HVAC systems that allows compressors to run at varying speeds.


Regular upkeep needed to keep HVAC systems running efficiently.

Make-up Air Unit

An HVAC device that pulls fresh air from outside to replace indoor exhaust air.

Merv Rating (Minimum Efficiency Reporting Value)

A measurement scale for air filters based on their ability to trap particles.

Multi-Split System

An HVAC system that connects multiple indoor units to a single outdoor unit.

Packaged Unit

An HVAC system in which all components are enclosed in a single unit.


A space where air collects, within a building or HVAC system, before distribution.

Portable Air Conditioner

A mobile air conditioning unit that can be moved from room to room.


The study of the properties of air and water vapor mixtures.

Reciprocating Compressor

A type of compressor in an HVAC system that uses pistons driven by a crankshaft.

Refrigerant Line

Tubing that transports refrigerant between components of an HVAC system.

Refrigeration Cycle

The cycle of stages (evaporation, compression, condensation, expansion) in refrigeration.

Remote Control

A device used to operate an HVAC system from a distance.

Return Air

Air that is drawn back into an HVAC system after it has been heated or cooled.

Screw Compressor

A type of gas compressor that uses two meshing screws to compress the air.

SEER (Seasonal Energy Efficiency Ratio)

A measure of an air conditioning unit’s cooling output over a typical cooling season divided by its energy input.

Split System

An HVAC system where the condensing unit is outside, and the evaporative unit is inside.

Supply Air

Air that is heated, cooled, humidified, or filtered and then distributed throughout a building.

Thermal Zone

An area or group of rooms within a building controlled by a single thermostat.


A device that regulates the temperature of a system by turning heating or cooling on or off.

Ton of Cooling

A unit of measure used to describe the cooling capacity of an air conditioner, equal to the heat required to melt one ton of ice in 24 hours.

UVGI (Ultraviolet Germicidal Irradiation)

A method of disinfection that uses ultraviolet light to kill or inactivate microorganisms.

VAV (Variable Air Volume)

A type of HVAC system that varies the volume of air delivered to different parts of a building.


An opening that allows air to pass in and out of a system.

VRF (Variable Refrigerant Flow)

An HVAC system that allows for precise temperature control by varying the flow of refrigerant.


The division of a space into zones, each controlled independently by its HVAC system.