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Portable Cooling Glossary


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When it comes to choosing a portable air conditioner or evaporative cooler, consumers are often confused by many of the industry terms used to describe a cooler's efficiency and features. If you don't know the difference between BTUs and CFMs, this glossary can help demystify cooling jargon.


Air Change: Measures how quickly the air in an interior space is replaced by outside or conditioned air by ventilation and infiltration. This is often calculated by determining the number of times a home's air changes over with outside air.

Air Conditioner: A device that decreases the temperature and humidity of air which moves through it.

Air Cooler: Another term for an evaporative or swamp cooler. This type of device uses simple evaporation of water to cool the air.

Air Delivery: Measures how much air is pumped out of a device in volume of air per time, either cubic feet per minute or cubic feet per hour.

Air Flow: Measures the flow of air, often in CFMs. This should be carefully balanced to ensure maximum cooling efficiency and optimal operation.

Air Handler: The indoor component of an air conditioning or heating system that moves air throughout a home or building.

Air Throw Distance: Another measurement often used to describe an evaporative cooler's efficiency. This indicates the distance away from the front of the cooler one can still feel the flow of air. Helpful for deciding how many air coolers to purchase and where they should be positioned.

Air Throw Rate: The average speed of air when it leaves the air cooler outlet or opening.

Ambient Temperature: Also referred to as room temperature. This is a common term used to describe a certain temperature within an enclosed space at which human beings are accustomed.

Auto-Evaporative: A type of technology utilized by many portable air conditioners and involves evaporating condensed water and exhausting it through a main venting hose and through a window, drop ceiling, or wall. A portable AC with auto-evaporative technology does not need to be frequently emptied (unless used in an extremely humid climate).


BTU: An acronym for "British Thermal Units" and a unit of energy used in the power and heating and cooling industries. In terms of air conditioners, this describes a unit's power and cooling capacity. The higher the BTU rating, the stronger the air conditioner.

Blower: An air handling device that moves air in a distribution system.

Blower Control: A term used to describe the speed at which a blower fan rotates. Sometimes used to describe swamp coolers, higher blower control ratings equal greater cooling effects.


Capacity: The output or producing capability of a heating or cooling system; usually referred to in BTUs.

Carbon Filter: A filter that uses a piece of activated carbon to remove odors, contaminants, and impurities; sometimes used in portable air conditioners and swamp coolers to help filter the air.

Casters: A type of wheel; often found on the bottom of some appliances, including portable air conditioners and swamp coolers, for maneuverability.

CFM: An acronym for cubic feet per minute; can be used to measure the rate of air flow in an air conditioner or evaporative cooler.

Central Air Conditioner: A type of air conditioner that works from a central location to distribute air throughout a home or building.

Compressor: Often called the "workhorse" of a cooling system. This refers to a pump that moves the refrigerant from the indoor evaporator to the condenser and back to the evaporator again; circulates refrigerant.

Condensate: The result of condensation: the change of the physical state of aggregation of matter from the gaseous phase into the liquid phase. In portable air conditioners, this refers to the water that is removed from the air, which is either collected into a bucket or tray, or exhausted through a hose.

Condenser Coil: A network of refrigerant-filled tubes where heat leaves the hot refrigerant vapor. This vapor is then condensed into a liquid capable of absorbing more heat.

Cooling Capacity: Measures the cooling power of a portable air conditioner; most commonly stated in BTUs.

Cooling Pads: Otherwise known as cool media. Pads that are found in an evaporative cooler; water is directed onto these pads and fresh, outside air is pulled through the moist pads where it is cooled by evaporation and circulated through an area.


Decibel: Expressed as "dB," this is the unit used to measure the intensity of a sound, and is commonly used by portable air conditioner and evaporative cooler manufacturers to determine how loud a unit will operate.

Dehumidification: The process of reducing the level of humidity of the air. Due to the refrigeration cycle, portable air conditioners also act as dehumidifiers.

Direct Evaporative Cooling: Refers to a type of evaporative cooling system in which a blower forces air through a water-soaked pad which acts like an air filter as it is cooled and humidified. As a result, humidity is also added to the air. Portable swamp coolers most often utilize this type of cooling technology.

Drain Bucket: A receptacle found in a portable AC that collects the condensate and which needs to be frequently emptied.

Drain Hose: A hose that is connected to a portable air conditioner that allows for water to be continuously drained outside.

Ductwork: Channels or pipes that carry air throughout a home or building.


EER: An acronym for "Energy Efficiency Ratio." This measures how energy efficient an air conditioner is at a specific level (usually 95° F), and can be calculated as a ratio of BTUs to the power input in watts. The higher the EER, the more energy efficient the portable air conditioner.

Energy Star: Energy Star qualified appliances and air conditioners meet strict energy efficiency guidelines set by the EPA and the U.S. Department of Energy and use at least 10% less energy than conventional models.

Evaporation: The process by which water is converted from its liquid form to its vapor form; the basic working principle behind evaporative coolers.

Evaporative Cooler: Also known as a swamp or air cooler; uses the simple process of evaporating water into the air to provide a natural and energy-efficient means of cooling; best suited for hot, dry areas with low humidity.

Evaporator Coil: A tube within an air conditioner that allows the highly compressed, liquid refrigerant to rapidly expand to a gas. This tube also absorbs heat from the air and disperses that heat outside by blowing the air over the condenser coil.


Fan Coil: The indoor section of a heat pump system which is made up of a blower and refrigerant coil.

Filter: A device used to remove dust, dirt, and other particulates from the air; frequently employed by portable air conditioners and swamp coolers to improve air quality.

Float Valve: A mechanism that regulates fluid level by using a float to control the filling of water in the water tank; used in swamp coolers to regulate water levels.

Freon: A general term that is used to identify any number of partially or completely halogenated simple hydrocarbons containing fluorine, chlorine, or bromine, which are used as refrigerants in air conditioning systems.


Heat Exchanger: In air conditioners, this refers to the condenser and evaporator coils and describes where heat moves from a substance or surface with a higher temperature to a lower temperature.

Heat Loss: The amount of heat lost (measured in BTUs) from a space to be conditioned due to outside temperatures and design conditions.

Heat Pump: A type of air conditioner that contains a valve that lets it switch between cooling and heating.

HEPA Filter: An acronym for "High Efficiency Particulate Absorbing Filter" and refers to a type of filter that can eliminate up to 99.97% particles 0.3 microns or larger; sometimes used in portable air conditioners or swamp coolers as a way to clean the air.

Humidistat: A controller that measures and controls relative humidity; may be used to control either humidifying or dehumidifying equipment; sometimes found on swamp coolers.

Humidity: The amount of moisture in the air.

HVAC: An acronym for "Heating, Ventilation, and Air Conditioning." An HVAC system can also include moisture control and air cleaning.


Ice Tank: An ice receptacle often found in evaporative coolers; used to enhance cooling and to further reduce the ambient temperature.

Indirect Evaporative Cooling: Refers to a type of evaporative cooling system in which a closed circuit makes use of a heat exchanger and does not add any moisture into the air.

Ionizer: A device that purifies the air by creating negative ions which remove microscopic particles; can be found in some portable ACs and swamp coolers as a way to improve air quality.


Louvers: Horizontal slats found on portable ACs or swamp coolers for admitting cool air; if adjustable, they can provide better control of air flow.


Operating Cost: The day-to-day cost of running your heating or cooling equipment based on energy usage.

Oscillation: In portable coolers, this usually refers to swinging fans or louvers that provide enhanced cooling and fanning performance, as well as improved air circulation.

Outdoor Air: Air that is taken from the external atmosphere and not previously circulated through the system.


Portable air conditioner: Compact air conditioners that do not require permanent installation and can be moved from room to room to provide spot or supplemental cooling.


R22: Also known as Chlorodifluoromethane or difluoromonochloromethane; commonly used as a refrigerant in air conditioning applications.

Refrigerant: A substance that produces a refrigerating effect while expanding or vaporizing, and is used by portable air conditioners during the refrigeration cycle.

Refrigerant Charge: The amount of refrigerant required by a particular cooling system.

Relative Humidity: The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature; normally expressed as a percentage.


SEER: An acronym for "Seasonal Energy Efficiency Ratio." Rating that describes the efficiency of an air conditioner, and is the amount of cooling the equipment delivers for every dollar spent on electricity. The higher the SEER, the more efficient the unit.

Self-Contained System: Refers to a unit where all the components are contained within one cabinet, such as portable air conditioners and window ACs.

Server Room: A room that houses computer servers; common portable air conditioner application.

Split Air Conditioner: A type of air conditioner that is similar to a central air conditioning unit but more affordable. They work by splitting the hot side from the cold side of the air conditioner, and are flexible for zoning, heating, or cooling individual rooms.

Sump: A pit or reservoir that serves as a drain or receptacle for liquids and commonly found in swamp coolers.

Swamp Cooler: Also known as an evaporative or air cooler; uses the simple process of evaporating water into the air to provide a natural and energy-efficient means of cooling; best suited for hot, dry areas with low humidity.


Thermostat: A device used for regulating the temperature of a system so that the system's temperature is maintained near a desired set point temperature; commonly found in air conditioners.

Through-the-Wall Air Conditioner: A type of air conditioner that is mounted into a wall and provides a cooling effect by exchanging inside air with outside air.

Timer: On a portable cooler, this is used to describe a device located on the unit that is used to control the sequence of the cooling process.


Variable Speed Motor: A type of fan motor used in some cooling systems that is designed to change its speed based on your cooling requirements. When used in conjunction with a thermostat, this helps keep the appropriate temperature air circulating throughout your home.

Venting: In portable air conditioners, this describes the process in which warm, humid air from the indoors is transferred outdoors via a hose and window kit; this is necessary for a portable air conditioner to cool.


Window Air Conditioner: A type of air conditioner that is installed into a window of a room and designed to cool that room.



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