A
Absorber
The absorber is the part of the solar collector that collects (absorbs) the incoming solar radiation and transforms it into heat.
Absorption
The absorption specifies the percent of the radiation on the absorber area that is transformed into heat.
AC (Alternating Current)
A type of current where the polarity is perpetually reversing, causing the directional flow in a circuit to reverse at regular intervals.
ACCA
ACCA is a non-profit association whose membership includes more than 60,000 professionals and 4,000 businesses in the indoor environment and energy services community. Their website can be found at www.acca.org
ACH, Air Changes Per Hour
The number of times that air in a building is completely replaced with outdoor air in one hour.
Acoustical
Relating to sound, the science of sound, or a sense of hearing.
Advanced Reciprocating Compressor
Type of compressor that uses a more efficient process for compressing refrigerant for better cooling efficiency.
Aeration
Act of combining substance with air.
AFUE
Annual Fuel Utilization Efficiency. Indicated as a percentage, your furnace's AFUE tells you how much energy is being converted to heat. For example, an AFUE of 90 means that 90% of the fuel is being used to warm your home, while the other 10% escapes as exhaust with the combustion gases. The higher the AFUE, the higher the efficiency of your furnace.
AGA
American Gas Association, Inc.
AHRI
The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) is the trade association representing manufacturers of HVACR and water heating. Their website can be found at www.ahrinet.org
AHU (Air Handling Unit)
The part of the A/C system that contains the blower, cooling (evaporator) coil, and heater.
Air Change
The amount of air required to completely replace the air in a room or building; not to be confused with recirculated air.
Air Cleaner
A device that removes allergens, pollutants and other undesirable particles from air that is heated or cooled.
Air Conditioner
A device that changes humidity levels, temperature or quality of air.
Air Cooled System
A type of air conditioning system that uses air as a condensing medium and R-22 or R-410A as a refrigerant. In most air-cooled systems, the condenser is located outside, and the refrigerant is piped to it from the indoor unit. In air conditioning, the heat from the indoor space is transferred to the outside air. In a heat pump, the heat is drawn from the outdoor air and is used to heat the indoor air.
Air Cooler
Mechanism designed to lower temperature of air passing through it.
Air Diffuser
Air distribution outlet or grille designed to direct airflow into desired patterns.
Air Diffusion
Distribution of the air in a space, called the treated space, by means of devices, called air terminal devices, in a manner so as to meet certain specified conditions, such as air change rate, pressure, cleanliness, temperature, humidity, air velocity and noise level.
Air Distribution
The transportation of a specified air flow to or from the treated space or spaces, generally by means of ductwork.
Air Filtration System
A device that removes allergens, pollutants and other undesirable particles from air that is heated or cooled.
Airflow Volume
Measured in cubic feet per minute (cfm), this is the amount of air circulated in a space.
Air Handler
The portion of your air conditioner or heating system that delivers air from one place to another, usually via ductwork.
Air heat pump
System that uses heat in the air to heat buildings.
Air Infiltration
Leakage of air into rooms through cracks, windows doors and other openings.
Air Purifier
Air purifiers treat 100% of the air flowing through your HVAC system before it even circulates, removing particulates, bacteria and viruses from the air.
Air Sensor
A device that registers changes in air conditions such as pressure, velocity, temperature, or moisture content.
Air Source Equipment
Heat pumps or air conditioners that uses the outdoor air to transfer heat to and from the refrigerant in the unit.
Air Terminal Device
A device located in an opening provided at the boundaries of the treated space to ensure a predetermined motion of air in this space.
Air Turnover Rate
The amount of air required to completely recirculate the air in a room or building one time would equal an “air turnover rate” of 1.0. This term is also called the “air change rate” in some cases.
Air Turnover Unit
Equipment typically located in the space to be conditioned that uses a high sidewall supply and low sidewall return concept to heat or cool the space. These units are typically made up of several sections stacked vertically and can include filters, heating sections, cooling coil sections, and air distribution sections as required by the application.
Air Vent
A fitting used to vent air manually or automatically from a system.
All-In-One System
An air conditioning and/or heating system in which all components are in one cabinet. Used in certain localities and for certain building types, the all-in-one system is installed either beside or on top of your home.
Allergen
A substance that causes an allergic reaction. It includes dust, pollen, pet hair and dander, dust mites, mildew, lint, fungus, most tobacco smoke, cooking grease and bacteria.
Anemometer
An instrument used to measure air velocities.
Annual efficiency
Important figure for assessing the energy efficiency of gas fired equipment. The annual efficiency designates the percentage ratio of the heat energy used to heat vs wasted as a byproduct of combustion.
ANSI
American National Standards Institute is a nonprofit organization that publishes safety standards for the HVAC industry. These standards are used by other organizations and local code authorities to create test protocols that prove equipment can be operated safely when installed properly.
ARI (Air-Conditioning and Refrigeration Institute)
Air-Conditioning and Refrigeration Institute is a nonprofit, voluntary organization comprised of heating, air conditioning and refrigeration manufacturers. ARI publishes standards for testing and rating heat pumps and air conditioners to provide you with a standardized measure of comparison. So, ARI ensures a level of performance within the industry.
ASHRAE
American Society of Heating, Refrigerating and Air-Conditioning Engineers is a global society advancing human well-being through sustainable technology for the built environment. The Society and its members focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability within the industry. Their website can be found at www.ashrae.org.
ASTM
American Society for Testing and Materials.
Atmospheric Pressure
The pressure exerted upon the earth's surface by the air because of the gravitational attraction of the earth. Standard atmosphere pressure at sea level is 14.7 pounds per square inch (psi). Measured with a barometer.
Automatic Control
Controls that react to a change in conditions to cause the condition to stabilize.
Automatic Expansion Valve
A refrigerant control valve that maintains a constant pressure in an evaporator.
Axial Fan
A device that propels air in an axial direction.
B
Balancing
Process of adjusting the flow of air in duct systems, or water flow in hot-water heating systems.
Barometer
An instrument for measuring atmospheric pressure.
Beckett Burner
A burner assembly within your oil furnace, providing combustion for heating oil.
Bioaerosols
Bioaerosols, or biological aerosols, are tiny airborne particles that are biological in nature. High concentrations of bioaerosols in indoor air can lead to respiratory problems and disease. Maintaining proper home humidity levels and installing advanced filtration devices, such as the Healthy Climate PureAir™ air purification system, can help reduce bioaerosols and maintain a healthy environment.
Blower
A piece of equipment designed to move air through a system. Usually refers to the air handling unit or air handler.
Boiler efficiency
Unit of measurement that specifies how much heat can be used from a fuel type. For this, flue gas and radiation losses are considered.
Bosch Heatronic
The electronic "brain" from Bosch guarantees optimal operation of the heating system and easy operation of the heating appliance.
Brine
Mixture of anti-freeze and water to prevent freezing.
BTU
British Thermal Unit. Used for both heating and cooling, BTU is a measure of the heat given off when fuel is combusted. Or for cooling, it's a measure of heat extracted from your home. (One BTU is approximately equal to the heat given off by a wooden kitchen match.)
BTUH
A British Thermal Unit (BTU) is the unit of heat required to raise 1 pound of water by 1 degree Fahrenheit. BTUH is British Thermal Units per Hour.
Buffer tank
Energy is stored temporarily in the buffer tank which is always necessary if there is an over or under supply.
Burner
The device that facilitates the combustion of air and gas.
Burner Orifice
The opening in the burner through which the gas or fuel passes prior to combustion.
C
Capacity
The ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTUs. For cooling, it is usually given in tons.
Carbon Dioxide
A by-product of natural gas combustion that is not harmful.
Carbon Monoxide
A colorless, odorless, highly poisonous gas produced when carbon-based fuels, such as natural gas, burn without enough air. When carbon monoxide leaks into your home’s air, it can lead to serious health problems for your family. Regular maintenance of your home’s heating and ventilation system will help ensure it’s not a source of a carbon monoxide leak.