HVAC Glossary
Your comprehensive guide to heating, ventilation, and air conditioning terminology. Understand the language of HVAC systems with clear, expert definitions.
Why Understanding HVAC Terms Matters
Whether you're researching a new HVAC system, troubleshooting an issue, or simply want to communicate better with your technician, understanding HVAC terminology helps you make informed decisions about your home comfort and energy efficiency.
This glossary covers everything from basic concepts like BTUs and SEER ratings to advanced terms used by HVAC professionals in the Portland area.
A
Absorption Chiller
A refrigeration system that uses heat rather than mechanical energy to drive the refrigeration cycle. Commonly used in large commercial applications.
Air Balance
The process of adjusting HVAC systems to ensure even and proper air distribution throughout a facility, optimizing comfort and efficiency.
Air Conditioner (AC)
A device that removes heat and humidity from indoor air to maintain comfortable temperatures during warm weather. air conditioning company near me
Air Handler
An indoor unit that circulates and conditions air within an HVAC system, typically containing a blower, heating/cooling elements, and filters.
Air Quality
A measure of the cleanliness and healthiness of indoor air, affected by pollutants, allergens, humidity, and ventilation.
Airflow
The movement of air through a space, driven by HVAC equipment. Measured in CFM (cubic feet per minute).
Ambient Air
The outside air temperature and conditions surrounding a building, typically used for ventilation purposes.
Antibacterial Filter
An air filter designed to remove or neutralize bacteria and microorganisms from the air stream.
B
Balanced Airflow
An HVAC distribution system that provides equal air volume across all zones, ensuring consistent comfort throughout a building.
Blower
A fan component in HVAC systems that moves air through ductwork and into living spaces.
BTU (British Thermal Unit)
A measurement of heating or cooling capacity. One BTU is the amount of energy needed to raise one pound of water by one degree Fahrenheit.
Bypass Damper
A device that controls airflow by allowing air to bypass the main air handler, helping to regulate pressure in zoned systems.
C
Capacity
The maximum heating or cooling output an HVAC unit can provide, typically measured in tons (for cooling) or BTUs (for heating).
CFM (Cubic Feet per Minute)
A measurement of air volume flow rate, indicating how much air moves through a system per minute.
Chemical Cleaning
The use of specialized chemical agents to clean HVAC components such as coils, removing buildup that reduces efficiency.
Chillers
Large refrigeration machines that remove heat from liquid (usually water) via vapor-compression or absorption cycles, commonly used in commercial buildings.
Coil
A component where heat transfer occurs in HVAC systems. Evaporator coils absorb heat; condenser coils release it.
Condensate
Liquid water produced as a byproduct when warm air passes over cold evaporator coils during cooling and dehumidification.
Condensation Drain Line
A pipe that directs condensate water away from HVAC units to prevent water damage and maintain efficiency.
Compressor
The heart of an air conditioning or heat pump system that pressurizes refrigerant and circulates it through the system.
D
Damper
A movable plate in ductwork that regulates or stops airflow, used for balancing and zoning.
Dehumidification
The process of removing excess moisture from indoor air to improve comfort and prevent mold growth.
Dehumidifier
A device that removes excess moisture from air to control humidity levels, improving comfort and air quality.
Duct
Metal or flexible tubing that distributes heated or cooled air throughout a building.
Ductless Mini-Split System
A small-scale heating and cooling system that doesn't require ductwork, consisting of an outdoor compressor and one or more indoor air handlers. ductless mini-split installers near me
E
EER (Energy Efficiency Ratio)
A rating that measures air conditioner energy effectiveness under specific conditions. Higher numbers indicate better efficiency.
Evaporative Cooler
A device that uses water evaporation to reduce air temperature, also known as a "swamp cooler." Most effective in dry climates.
Evaporator Coil
The indoor coil in an AC or heat pump system where refrigerant absorbs heat from indoor air.
Expansion Valve
A component that reduces refrigerant pressure before it enters the evaporator coil, allowing it to absorb heat efficiently.
F
Fan Coil Unit
A device containing a fan and heating/cooling coil used in HVAC systems to regulate air temperature in individual rooms or zones.
Filter
A device that removes particles, dust, and contaminants from air or liquids in HVAC systems.
Freon
A brand name for refrigerant (now generic term), though many modern systems use more environmentally-friendly refrigerants like R-410A.
Furnace
A heating system that uses gas, oil, or electricity to warm air, which is then distributed throughout a building via ductwork. furnace company Portland
H
Heat Exchanger
A system component that transfers heat between fluids without allowing them to mix. Critical for furnace safety and efficiency.
Heat Load
The amount of heating or cooling needed to maintain desired temperatures in a space, used for proper system sizing.
Heat Pump
A system that transfers heat energy using refrigeration technology. Can both heat and cool by reversing the refrigeration cycle. heat pump company Portland
HEPA Filter
High-Efficiency Particulate Air filter that captures 99.97% of particles 0.3 microns or larger, including dust, pollen, and some bacteria.
HVAC
Heating, Ventilation, and Air Conditioning - the technology that provides indoor climate control and air quality.
Humidifier
A device that adds moisture to indoor air to prevent dryness, especially important during winter heating seasons.
I
IAQ (Indoor Air Quality)
The quality of air inside buildings, measured by levels of pollutants, allergens, humidity, and ventilation effectiveness.
Inverter Technology
Advanced technology allowing compressors to vary speeds continuously, providing precise temperature control and improved energy efficiency.
M
Maintenance
Regular upkeep of HVAC systems including cleaning, inspection, and tune-ups to ensure efficient operation and prevent breakdowns. AC maintenance Portland
Make-up Air Unit
A device that pulls fresh outside air into a building to replace air exhausted by ventilation systems.
MERV Rating
Minimum Efficiency Reporting Value - a scale (1-16) measuring an air filter's ability to trap particles. Higher numbers indicate better filtration.
Multi-Split System
An HVAC system connecting multiple indoor units to a single outdoor unit, allowing independent temperature control in different zones.
P
Packaged Unit
An HVAC system with all components (compressor, condenser, evaporator) housed in a single outdoor enclosure.
Plenum
A central air distribution space where air collects before being distributed through ductwork.
Portable Air Conditioner
A mobile cooling unit that can be moved between rooms, typically venting hot air through a window.
Psychrometrics
The study of physical and thermodynamic properties of air and water vapor mixtures, essential for HVAC design.
R
Reciprocating Compressor
A compressor type using pistons driven by a crankshaft to compress refrigerant gas.
Refrigerant
The chemical compound that circulates through HVAC systems, absorbing and releasing heat to provide cooling or heating.
Refrigerant Line
Copper tubing that transports refrigerant between indoor and outdoor components of an HVAC system.
Refrigeration Cycle
The process of heat transfer involving evaporation, compression, condensation, and expansion stages.
Return Air
Air drawn back into the HVAC system after circulating through a space, to be reconditioned and redistributed.
S
Screw Compressor
A compressor type using meshing helical screws to compress air or refrigerant, common in large commercial systems.
SEER (Seasonal Energy Efficiency Ratio)
A measure of cooling system efficiency over an entire season. Higher SEER ratings indicate better energy efficiency and lower operating costs.
Split System
The most common HVAC configuration with an outdoor condensing unit and an indoor evaporative unit connected by refrigerant lines.
Supply Air
Heated, cooled, humidified, or filtered air distributed throughout a building from the HVAC system.
T
Thermal Zone
An area in a building controlled by a single thermostat, maintaining uniform temperature conditions.
Thermostat
A device that regulates HVAC system operation by sensing temperature and controlling heating/cooling to maintain desired comfort levels. heating company near me
Ton of Cooling
A unit measuring air conditioner capacity. One ton equals 12,000 BTUs per hour of cooling.
U
UVGI (Ultraviolet Germicidal Irradiation)
Technology using ultraviolet light to kill or neutralize microorganisms in HVAC systems, improving indoor air quality.
V
VAV (Variable Air Volume)
An HVAC system that varies the air volume delivered to different building areas based on heating/cooling demand.
Vent
An opening that allows air to pass into or out of a space, part of the ventilation system.
Ventilation
The process of supplying fresh outdoor air and removing stale indoor air to maintain healthy indoor air quality.
VRF (Variable Refrigerant Flow)
An advanced HVAC system providing precise temperature control by varying refrigerant flow to multiple indoor units.
Z
Zoning
The division of a building into independently controlled temperature zones, allowing customized comfort and energy savings.
Still Have Questions About HVAC Terms?
Our team at Efficiency Heating & Cooling is always happy to explain HVAC concepts and help you understand your system better.
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