Air Conditioning Glossary from Edd Helms Group


Air Conditioning
Air Conditioning Glossary



Air Conditioner - Assembly of equipment for the simultaneous control of air temperature and relative humidity.

Accumulator: Tank on the suction side of a system that holds excess refrigerant to prevent slugging the compressor with liquid.

Air Cooled - Uses a fan to discharge heat from the condenser coil to the outdoors.

Air-cooled system A type of air conditioning system that uses freon as a refrigerant and air as a condensing medium. Typically, the air-cooled condenser is located outside and refrigerant lines are piped to it from the indoor unit.

AFUE (Annual Fuel Utilization Efficiency) - A rating that denotes the efficiency of gas heating equipment. It is the amount of heating your equipment delivers for every dollar spent on fuel. A higher rating indicates more efficient equipment. This rating is calculated in accordance with the Department of Energy test procedures.

Ambient Temperature - The temperature, usually of the air, that surrounds operating equipment.

Airflow: The distribution or movement of air.

Air Change: The amount of air required to completely replace the air in a room or building.

Air Diffuser: Air distribution outlet or grille designed to direct airflow into desired patterns.

Air Handler: Fan-blower, filter and housing parts of a system.

ASHRAE Standard 52-76 Industry standard for air filtration efficiency. For most data processing areas, a filtration efficiency of 20% is generally adequate.

ASHRAE Standard 90-75 The industry standard on energy conservation in new building design.

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BTU (British Thermal Unit) - The standard of measurement used for measuring the amount of heat required to raise the temperature of one pound of water by one degree (Fahrenheit).

BTUH - The number of BTUs in an hour.

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Central Air Conditioner System -System in which air is treated at a central location and carried to and from the rooms by one or more fans and a system of ducts.

Compressor - The pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again. The compressor is often called "the heart of the system" because it circulates the refrigerant through the loop.

Condenser - A device that transfers heat out of a refrigeration system to a medium via (either air, water, or a combination of air and water) that absorbs the heat and transfers it to a disposal point. There are three types of condensers: air-cooled condensers, water-cooled condensers, and evaporative condensers. Most residential systems have an air-cooled condenser.

Carbon Monoxide An odorless, poisonous, flammable gas produced when carbon burns with insufficient air. Condenser Coil - A series or network of tubes filled with refrigerant, normally located outside the home, that removes heat from the hot, gaseous refrigerant so that the refrigerant becomes liquid again.
Cooling Capacity - A measure of the ability of a unit to remove heat from an enclosed space.

COP - Coefficient of Performance of a heat pump means the ratio of the rate of useful heat output delivered by the complete heat pump unit (exclusive of supplementary heating) to the corresponding rate of energy input, in consistent units and under operating conditions.

Charge: Amount of refrigerant placed in a refrigerating unit.

Comfort Zone: The range of temperatures, humilities and air velocities at which the greatest percentage of people feel comfortable.

Condensing Unit: Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser and returns it to the refrigerant control. The outdoor portion of a split system air conditioner contains the compressor and outdoor coil ignoring the reverse cycle operation, also the outdoor in a heat pump system.

CFM The abbreviation for cubic feet per minute, commonly used to measure the rate of air flow in an air conditioning system.

Chilled water system A type of air conditioning system that has no refrigerant in the unit itself. The refrigerant is contained in a chiller, which is located remotely. The chiller cools water, which is piped to the air conditioner to cool the space.

Comfort air conditioning Compact air conditioning systems are designed for the comfort of people, not the protection of computer-based electrical systems. Unlike people, computers generate dry (sensible) heat, but not humidity. Only about 60-70% of a comfort system's total capacity is dedicated to the removal of sensible heat, while 30-40% is for dehumidification. With a large percentage of their total capacity devoted to the removal of moisture, comfort systems can lower room humidity far below acceptable standards, and they have no provisions for adding moisture. Improper humidity levels can cause static electricity discharges during dry seasons and condensation forming within the electronic equipment during wet seasons.

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Decibel, a measure of sound.

DOE -The Department of Energy. A federal agency that sets industry efficiency standards and monitors the use of various energy sources.

Dehumidification: The reduction of water vapor in air by cooling the air below the dew point; removal of water vapor from air by chemical means, refrigeration, etc. Defrost Cycle: The process of removing ice or frost buildup from the outdoor coil during the heating season. Duct: A pipe or closed conduit made of sheet metal, fiberglass board, or other suitable material used for conducting air to and from an air handling unit.

Direct expansion systems One of two types of basic cooling media (the other is chilled water). Direct expansion systems utilize refrigerant for cooling and dehumidification. They are generally provided with complete refrigeration circuits for redundancy. The three most common methods of heat rejection are air cooled, water cooled and glycol cooled.

Downflow Refers to a type of air conditioning system that discharges air downward, directly beneath a raised floor.

Damper - Found in duct work, this movable plate opens and closes to control airflow. Dampers are used to regulate airflow to certain rooms.

Ductwork tubes or channels that carry air throughout your home

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EER - Energy Efficiency Ratio means the ratio of the cooling capacity of the air conditioner in British Thermal

Units per hour, to the total electrical input in watts under ARI-specified test conditions.

Emergency Heat (Supplementary Electric Heat): The back up electric heat built into a heat pump system. The same as an auxiliary heater, except it is used exclusively as the heat source when the heat pump needs repair.

Evaporator- Absorbs heat from the surrounding air or liquid and moves it outside the refrigerated area by means of a refrigerant. It is also known as a cooling coil, blower coil, chilling unit or indoor coil.

Evaporator Coil - A series or network of tubes filled with refrigerant located inside the home that take heat and moisture out of indoor air as liquid refrigerant evaporates.

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Free Delivery - There are no ducts and the unit may be installed in the field without ducts if needed.

Forced air: heating and or cooling system that connects to the conditioned space with duct-work that uses air as the moving fluid. The heating or cooling can come from any number of sources.

Freon  Any of a group of partially or completely halogenated simple hydrocarbons containing fluorine and usually chlorine or bromine, often used as refrigerants and aerosol propellants.

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Ground Water-Source - Water from an underground well is being used as the heat source or heat sink for a heat pump.

Glycol-cooled system A type of air conditioning system that uses freon as a refrigerant and a water/glycol solution as a condensing medium. Typically, the glycol-cooled condenser is located inside the air conditioner with the rest of the refrigeration components. Water/glycol is piped to the unit from a drycooler or other suitable source. The glycol keeps the solution from freezing during winter operation.

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HVAC - Heating, ventilation, and air conditioning.

Heat Pump - An air conditioner capable of heating by refrigeration. It may or may not include a capability for cooling. Outside air or water is used as a heat source or heat sink, depending upon whether the system is heating or cooling.

Heating Capacity - A measure of the ability of a unit to add heat to an enclosed space.

HSPF - Heating Seasonal Performance Factor means the total heating output of a heat pump in British Thermal Units during its normal usage period for heating divided by the total electrical energy input in watt-hours during the same period.

Heat Gain: The amount of heat gained, measured in BTU's, from a space to be conditioned, at the local summer outdoor design temperature and a specified indoor design condition.

Heat Loss: The amount of heat lost, measured in BTU's from a space to be conditioned, at the local winter outdoor design temperature and a specified indoor design condition.

Humidifier: A device that adds moisture to warm air being circulated or directed into a space.

Humidistat: A device designed to regulate humidity input by reacting to changes in the moisture content of the air.

Humidification The process of adding moisture to the air within a critical space.

Heat Exchanger  A device for the transfer of heat energy from the source to the conveying medium.

Humidity  The amount of moisture in the air. Air conditioners remove moisture for added comfort.

HSPF - Heating Seasonal Performance Factor, a rating used in measuring the heating efficiency of a heat pump. The higher the number, the more efficient the unit.

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Insulation - Any material that slows down the transfer of heat.

Indoor coil: The coil on a heat pump that is located inside. This is so not to be confused with the evaporator on an air-conditioning system.

Infiltration: Air flow inward into a space through walls, leaks around doors and windows or through the building materials used in the structure.

ICM - Integrally Controlled Motor. A specially engineered, variable-speed motor. ICM motors are more than 90% efficient versus 60% efficiency for conventional motors. Continuous comfort, whisper-quiet operation and ultimate system efficiency are the benefits of the indoor products graced with the ICM motor.

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(K) Factor - The insulating value of any material. Also known as conductivity.

Kilowatt (kW) - Equal to 1,000 watts.

Kilowatt-hour (kWh) - A common unit of electrical consumption measured by the total energy created by one kilowatt in one hour.

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Latent cooling capacity An A/C system's capability to remove moisture from the air.

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Mainframe chiller system Water-cooled mainframe computers rely on mainframe chillers for a continuous supply of liquid coolant to maintain processor temperature within a specified range. Exceeding the temperature specification or an interruption of coolant flow can cause a sudden shut-down, interruption of computer operations, and possible hardware damage, requiring costly repairs.

Microprocessor controls A control system that uses computer logic to operate and monitor an air conditioning system. Microprocessor controls are commonly used on modern precision air conditioning systems to maintain precise control of temperature and humidity and to monitor the units operation.

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Outdoor coil: The coil on a heat pump system that is located out side or in the ground loop of a groundsourced heatpump. This is so not to be confused with the condensor on an airconditioning system.

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Packaged or self-contained: Refrigeration system where everything including the air moving hardware is kept in one box, such as a window air conditioner or a roof-top unit

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Radiant: System that uses hot surfaces to radiate or convect heat into the environment. Without the use of fans or blowers.

Receiver: Tank on the liquid side of a system that holds excess refrigerant in the system that needs to be there for proper operation.

Refrigerant: Substance used in refrigerating mechanism. It absorbs heat in evaporator by change of state from a liquid to a gas, and releases its heat in a condenser as the substance returns from the gaseous state back to a liquid state.

Refrigerant Lines: Copper lines connecting the outdoor unit and the indoor unit.

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SEER-(Seasonal Energy Efficiency Ratio) - A rating that denotes the efficiency of air conditioning equipment. It is the amount of cooling your equipment delivers for every dollar spent on electricity. It is the ratio of cooling delivered by a system, measured in BTUs, to the dollar cost of the electricity to run the system, as measured in watt-hours. This ratio is determined using specified federal test procedures. The higher the SEER, the more efficient the unit. The more efficient the unit, the lower the operating cost.

Sensible Heat - Heat energy that causes a rise or fall in the temperature of a gas, liquid or solid when added or removed from that material. Sensible heat changes the temperature by changing the speed at which the molecules move.

Sensible cooling capacity An A/C system's capability to remove heat from the air.

Single Package -A central air conditioner which combines both condenser and air handling capabilities in a single packaged unit.

Split System - A central air conditioner consisting of two or more major components. The system usually consists of a compressor-containing unit and condenser, installed outside the building and a non-compressor -containing air handling unit installed within the building. This is the most common type of system installed in a home.

Switchover Valve  A device in a heat pump that reverses the flow of refrigerant as the system is switched from cooling to heating. Also called a reversing valve or four-way valve.

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Thermostat  A temperature control device, typically found on a wall inside the home, that consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system. Programmable thermostats allow you to program different levels of comfort for different times of the day.

Ton -The unit of measurement for air conditioning system capacity. One ton of air conditioning removes 12,000 Btu's of heat energy per hour from a home. Central air conditioners are sized in tons. Residential units usually range from 1 to 5 tons (1200BTU = 1 ton of A.C)

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Upflow A type of air conditioning system that discharges air upward, into an overhead duct system.

Upflow Furnace - A furnace that pulls return air in from the bottom and expels warm air from the top

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Vapor seal A vapor seal is an essential part of preventing moisture infiltration into or migration out of a critical space, such as a data processing center or other room that contains sensitive electronic instrumentation. Essentially, a vapor seal is a barrier that prevents air, moisture, and contaminants from migrating through tiny cracks or pores in the walls, floor, and ceiling into the critical space. Vapor barriers may be created using plastic film, vapor-retardant paint, vinyl wall coverings and vinyl floor systems, in combination with careful sealing of all openings (doors and windows) into the room.

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Year-Round: Air Conditioner which uses gas or oil for heating.