HVAC Glossary & Terminology

Navigating the world of swamp coolers, air conditioning, heating, and HVAC systems can be quite challenging due to the multitude of acronyms and specialized terminology. This glossary is designed to help you comprehend the key terminology you might come across while deciding on air conditioning repairs or installations. If you want more information or clarification, call us at: 480-704-4828

A

Alternating Current (AC): This refers to a form of electrical current in which the direction of flow reverses periodically, leading to cyclic variations in polarity within a circuit.

ACCA: The Air Conditioning Contractors of America (ACCA) is a non-profit organization that boasts a membership of over 60,000 professionals and 4,000 businesses dedicated to the indoor environment and energy services sector.

Acoustical: Pertaining to sound, acoustics encompasses the study of auditory phenomena and the sense of hearing.

AFUE: The Annual Fuel Utilization Efficiency is a metric employed to evaluate the performance of furnaces by calculating the ratio of usable heat output to the total heat input.

AGA: The American Gas Association, Inc. (AGA)

AHRI: The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) serves as the trade organization for manufacturers of HVACR systems and water heating solutions. More details can be found at www.ahrinet.org.

Air Conditioner: This is a device designed to regulate humidity, temperature, and air quality within a given space.

Airflow Volume: Represented in cubic feet per minute (cfm), this figure quantifies the volume of air that moves through an area.

Air Handler: The air handler is the internal component of an air conditioning system, which includes the fan responsible for circulation and the coils for evaporating (in the summer) or condensing (in the winter).

ASHRAE: The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) is a worldwide organization that promotes human health through innovative technologies for the built environment. The organization and its members emphasize building systems, enhancing energy efficiency, ensuring indoor air quality, and promoting sustainability in the industry.

B

BTU: A British Thermal Unit measures the heat energy needed to change the temperature of one pound of water by one degree Fahrenheit.

BTU/h: This term stands for British Thermal Units measured on an hourly basis.

Burner: This is the component that enables the combustion of air mixed with gas.

Burner Orifice: The opening within the burner that allows gas or fuel to flow before it ignites.

C

Capacity: The capacity of HVAC systems refers to the amount of heating or cooling provided, quantified in BTUs per hour.

Celsius: It is a temperature scale where water freezes at 0° and boils at 100° under standard atmospheric conditions.

Central AC System: A central air conditioning unit, often referred to as central A/C, functions by cooling a residence/property through the distribution of chilled air via a system of ducts and vents.

Central Gas Furnace: A central gas heating system is designed to utilize natural gas or propane to generate warmth and circulate heated air throughout a residence/property.

CFM (Cubic Feet per Minute): This is a unit that measures the volume of airflow.

Charging a System: This term describes the process of adding coolant or refrigerant to an HVAC unit.

Coil: The evaporator coil connects to the furnace’s airflow outlet. It circulates conditioned refrigerant to cool the space during summer and heat it during winter. As warm air flows over the evaporator coil, it loses temperature and moisture, resulting in cooler indoor air. Proper sizing and rating of the evaporator coil are crucial for maximizing the performance and comfort of your air conditioning or heat pump system.

Compressor: A device that elevates the pressure of refrigerant gas.

Condensate: When warm air moves across the chilled evaporator coil, moisture collects on the coil, forming liquid condensate that is removed from the equipment through mechanical drainage.

Condenser Coil: Typically found outdoors, this coil extracts heat from refrigerant during the summer, enabling the transformation of refrigerant from gas to liquid and completing the refrigeration cycle.

Condenser Fan: A fan that enhances air circulation over the condenser coil to assist in expelling heat from the refrigerant.

CSA: Refers to the Canadian Standards Association.

D

DC: Direct Current refers to a type of electrical current that flows uniformly in one direction.

Damper: Located at junction points in duct systems, these metal plates adjust air flow into a particular area by either opening or closing.

Degree-Day: This is calculated by subtracting the area’s average outdoor temperature from 65º Fahrenheit, serving as a metric to gauge the heating or cooling needs of a building.

Dehumidifier: An appliance designed to extract moisture from the air.

Diffuser: An air supply duct grille featuring vanes that strategically direct the outflowing air in specific patterns.

DOE: The Department of Energy, which can be accessed at www.energy.gov.

Downflow Furnace: A type of furnace that takes in air from the top and discharges it at the bottom.

Drain Pan: Also known as a condensate pan, this component collects the condensate as refrigerant vapor is converted to liquid, transporting it to the drain line.

Dry Bulb Temperature: The measurement of temperature that does not factor in humidity levels.

Ductwork: A system of conduits made from metal, fiberboard, or flexible materials that transports air from an HVAC unit throughout a building’s zones.

E

EER: The Energy Efficiency Ratio for a cooling appliance calculates the output cooling energy (measured in BTUs) compared to the electrical energy input under specific operating conditions.

Energy Star®: A voluntary program initiated by the U.S. Environmental Protection Agency, aimed at helping individuals and businesses achieve greater energy efficiency and protect the environment.

EPA: The U.S. Environmental Protection Agency is a federal body dedicated to safeguarding human health and the environment through regulation enforcement based on legislation passed by Congress.

Evaporator Coil: Referred to as an indoor coil, this component absorbs heat from the air to transform the liquid refrigerant flowing through it into a vapor, thereby starting the cooling process.

Expansion Valve: A device that controls the flow of refrigerant, adjusting it based on temperature or pressure requirements.

F

Fahrenheit: A temperature scale where water freezes at 32 degrees and boils at 212 degrees under standard atmospheric conditions.

Fan: A machine comprising a motor and blower wheel that generates airflow.

Filter: Central heating and cooling systems typically incorporate multiple filters. The air filter is essential for the system’s intake ducting, preventing harmful particles from entering the equipment, requiring regular maintenance or replacement. Additionally, refrigeration systems include another filter, often called a drier, which acts as a strainer to eliminate dirt and unwanted particles.

Flue: A duct that expels combustion byproducts from a furnace.

Furnace: The primary gas-fueled element used for heating residential spaces, facilitating fuel and air combustion to generate heat which is then circulated throughout the home via a fan.

Fuse: A thin metal strip linking two sections of an electrical circuit, this component functions as a safety feature, melting under excessive electrical current to interrupt the circuit.

G

GAMA: Gas Appliance Manufacturers Association.

H

Heat Exchanger: An apparatus that transfers heat to a colder or warmer area or surface.

Heat Gain: The total heat added or produced within a specified area.

Heating Coil: A coil that serves as a heat source in heating systems.

Heat Loss: The total heat that is dissipated or extracted from a specified area.

Heat Pump: An appliance designed for both heating and cooling spaces by moving heat between two reservoirs.

Heat Transfer: The movement of heat from one location to another via conduction, convection, or radiation. Heat moves naturally from warmer to cooler regions.

HSPF: The Heating Seasonal Performance Factor (HSPF) is a term used to measure the efficiency of residential heat pump systems.

Humidifier: A device that adds moisture to the air.

Humidistat: A device that monitors humidity levels and activates or deactivates the humidifier accordingly.

Humidity: The presence of moisture in the air, typically resulting from water vapor.

I

Ignition: The process of raising a substance’s temperature to trigger a combustive reaction.

Interconnection Agreement: A linkage between power systems allowing them to utilize each other’s reserve capacities during critical periods.

J

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K

Kilowatt (kW): Equivalent to 1,000 watts.

L

Latent Heat: Energy released or absorbed during a constant-temperature process that induces a change of state, such as the heat of evaporation transitioning liquid to vapor at specific temperature and pressure.

M

Media: The intricate material within a filter that traps dirt, dust, mold, or bacteria.

Manufacturer Approved System: When replacing a condensing unit, furnace, or air handler, the new system must be manufacturer-approved and aligned with Air Conditioning, Heating and Refrigeration Institute (AHRI) standards. Note: Installing mismatched systems is highly discouraged.

N

NATE: North American Technician Excellence, the largest non-profit certification body for HVACR technicians, governed and supported by the HVACR industry. Their website can be found at www.natex.org.

NEC: National Energy Council / National Electric Code.

NEMA: National Electrical Manufacturing Association.

O

Orifice: An opening or aperture.

P

Package Unit: A unified heating and cooling system contained entirely within an outdoor unit.

Particulates: Tiny liquid or solid particles found in combustion emissions, with their quantity and size regulated by the U.S. Environmental Protection Agency for various sources such as vehicles and industrial operations.

Plenum: A pressurized chamber containing air or gas at higher than ambient pressure, serving to manage and distribute pressure evenly.

Preventative Maintenance: Regular HVAC maintenance, is an essential strategy for ensuring that heating, ventilation, and air conditioning systems operate optimally and securely. This proactive approach aids in avoiding potential system failures, prolongs the lifespan of the equipment, and can lead to significant savings on repair costs.

Programmable Thermostat: A thermostat that enables users to set a timed schedule of temperatures for their HVAC system, automating its operation.

PSI: Pounds per square inch, a pressure measurement indicating the force exerted by one pound-force on an area of one square inch.

PSIA: Pounds per square inch absolute, used to indicate pressure concerning a vacuum rather than the surrounding atmospheric pressure. As atmospheric pressure is around 14.7 psi at sea level, this is added to any pressure reading taken at that level.

PSIG: Pounds per square inch gauge, indicating that pressure measurements are taken relative to atmospheric pressure.

Psychrometric: The study of atmospheric states, particularly the moisture content in the air.

PVC: Polyvinyl chloride, a type of plastic material.

Q

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R

Radiant Floor: A heating system in which the floor consists of tubes or channels that circulate hot liquids, such as air or water.

Radiation: The process through which heat travels through matter or space via electromagnetic waves.

Reciprocating Compressor: A compressor type utilized in cooling systems that compresses refrigerant through piston action.

Refrigerant: The working fluid circulating in air conditioners, heat pumps, and refrigerators, responsible for heat transfer in and out of a space. This fluid has a low boiling point, allowing it to absorb and release heat effectively.

Refrigerant Charge: The quantity of refrigerant present within a system.

S

Scroll Compressor: Found in both basic and high-efficiency air conditioners, these compressors are favored for having fewer moving parts compared to reciprocating models, leading to enhanced efficiency, better tolerance for liquid refrigerant, and quieter operation.

SEER: The Seasonal Energy Efficiency Ratio is commonly used to evaluate air conditioner efficiency, defined by the Air Conditioning, Heating, and Refrigeration Institute as the cooling output during a regular cooling season relative to total electricity consumed during that time.

Self-Contained System: Another term for a package unit.

Sensible Heat: The heat that is added or removed from a system that induces a temperature change.

Sensor: An apparatus that detects changes in environmental conditions.

Single-Speed: A motor type that operates at maximum speed until it meets the desired temperature setting, after which it turns off. These motors typically run louder at startup, are less energy efficient than alternative types, and may lead to increased wear on mechanical components.

Split System: A configuration consisting of an outdoor unit paired with an indoor unit, unlike a package unit, typically offering enhanced efficiency and a variety of setup possibilities.

T

Thermostat: A wall-mounted device that monitors and regulates the performance of an HVAC system.

Thermostatic Expansion Valve: A device that maintains a consistent evaporator temperature through the regulation of refrigerant flow.

Ton: A unit of measurement equivalent to 12,000 BTUs per hour.

Two-Speed: Essential for high-efficiency air conditioners, these motors operate at low speed for cooling needs and switch to high speed if required. They reset to low speed once the desired temperature is reached, minimizing startup noise, enhancing energy efficiency, and reducing mechanical stress compared to single-speed motors.

U

Upflow Furnace: A furnace that draws air from the bottom and expels it from the top.

V

Vacuum: An area where the pressure is significantly lower than standard atmospheric pressure.

Variable-Speed: Ideal for high-efficiency air conditioners, variable-speed motors operate at multiple speeds, similar to a two-speed model, but with more settings for improved performance control and quieter operation, as well as greater energy efficiency and reduced stress on components.

Ventilation: The procedure of circulating air in and out of an indoor environment through mechanical means.

Volt: A unit measuring electrical potential and electromotive force.

Voltage: The exertion that drives electric current through conductors.

W

Watt: Defined as a joule per second, indicating the rate at which energy is transformed over time.

Wet Bulb Thermometer: A device used to assess the relative humidity of the air.

X Y Z

Zoning: A system that divides a space into distinct areas to facilitate more effective heating and cooling control.