| WORD | DEFINITION |
|---|
| Air Handler | An air handler, or air handling unit, is the indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. It is usually a large metal box containing important elements of an HVAC system that controls airflow and filtration. Lennox® air handlers are among the most efficient and quietest you can buy. |
| ABSOLUTE HUMIDITY | The weight of water vapor in a given amount of air. |
| ABSOLUTE PRESSURE | Pressure measured with the base of zero. |
| ABSOLUTE TEMPERATURE | A temperature scale expressed in degrees oF or oC using absolute zero as a base. Referred to as the Rankin or Kelvin scale. |
| ABSOLUTE ZERO | The temperature at which molecular activity theoretically ceases. -456.69 oF or -273.16 oC. |
| AFUE | Annual Fuel Utilization Efficiency. AFUE is a rating that reflects how efficiently a gas furnace converts fuel to energy. An AFUE of 90 means that approximately 90 percent of the fuel is utilized to provide warmth to your home, while the remaining 10 percent escapes as exhaust. |
| AIR BALANCING | Adjusting an air conditioning system so that the right amount of air is delivered to the right places in your home in order to achieve the right heating or cooling effect. |
| Air Cleaner | A device that removes allergens, pollutants and other undesirable particles from air that is heated or cooled. |
| Air Conditioner | An air conditioner is the most common home cooling method. Air conditioners can come in either split or package system varieties. |
| AIR CONDITIONING | The process of controlling the temperature, humidity, cleanliness and distribution of the air. |
| Air Conditioning, Heating and Refrigeration Institute (AHRI) | AHRI is the voice for heating and air conditioning contractors and consumers. This institute maintains standards across the industry and lobbies for policy changes in government. |
| Air Filtration System | A device that removes allergens, pollutants and other undesirable particles from air that is heated or cooled. |
| Air Handler | The indoor component of your air conditioner or heating system that moves air through your home. |
| AIR HANDLING UNIT(AHU) | Equipment with a heating element and/or cooling coil and other components in a cabinet or casing. |
| AIR, Standard Conditions | Conditions at which capacity ratings for air conditioning equipment is rated. |
| Air-Conditioning And Refrigeration Institute (ARI) | An industry trade association that develops standards for measuring and certifying product performance. For instance, ARI Standard 270 provides guidelines for establishing sound levels for outdoor air-conditioning equipment. |
| Airflow | This is a measurement of the amount of air that a device is able to supply. In HVAC, airflow is measured in CFM and has implications for the effectiveness of your heating and cooling equipment. If your airflow, CFM measurement, is too low you won’t be getting enough air distributed through your home, which can lead to hot or cold spots. |
| 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. Test. |
| All-In-One System | An air conditioning and/or heating system in which all components are located 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. |
| AMBIENT | Refers to the temperature surrounding a body or unit under test. |
| Annualized Fuel Utilization Efficiency (AFUE) | A measure of furnace heating efficiency. The higher the AFUE, the more efficient the furnace. |
| ATMOSPHERIC PRESSURE | The weight of a 1 unit column of the earth’s atmosphere. |
| BI-METAL | Two metals with different rates of expansion fastened together. When heated or cooled they will warp and can be made to open or close a switch or valve. |
| Bioaerosols | Microscopic living organisms suspended in the air that grow and multiply in warm, humid places. |
| BOILING POINT | The temperature at which the addition of any heat will begin a change of state from a liquid to a vapor. |
| British Thermal Unit (BTU) | A measurement of heat energy. One Btu is the amount of heat required to raise one pound of water by one degree Fahrenheit. The higher the Btu rating, the greater the heating capacity of the system. |
| British Thermal Unit Per Hour (BTUh) | British thermal units per hour. |
| BTU | British Thermal Unit. In scientific terms, it represents the amount of energy required to raise one pound of water one degree Fahrenheit. One BTU is the equivalent of the heat given off by a single wooden kitchen match. For your home, it represents the measure of heat given off when fuel is burned for heating, or the measure of heat extracted from your home for cooling. |
| Capacity | Capacity refers to the ability of a heating or cooling system to heat or cool a given amount of space. Typically, heating capacity is expressed in BTUs and cooling capacity is expressed in tons. The higher the capacity, the more heating or cooling power that unit supplies. |
| CAPILLARY TUBE | A refrigerant control consisting of a small diameter tube which controls flow by restriction. They are carefully sized by inside diameter and length for each particular application. |
| Carbon Monoxide | An odorless, colorless, tasteless, poisonous and flammable gas produced when carbon burns with insufficient air. |
| CENTIGRADE | A temperature scale with the freezing point of water 0 oC and the boiling point 100 oC at sea level. |
| Central Air-Conditioning System | System in which air is cooled at a central location and distributed to and from rooms by one or more fans and a series of ducts. |
| Certified Matched System | The Air Conditioning, Heating and Refrigeration Institute (AHRI) puts heating and cooling equipment through rigorous certification processes to ensure systems deliver the promised performance at certain test conditions. If the outdoor and indoor components of your heating and cooling systems aren’t matched, you may not get expected performance levels. |
| CFC | Chlorofluorocarbons, used as a refrigerant in air conditioners and heat pumps, linked to the depletion of the ozone layer. |
| CFM | Cubic Feet per Minute, a standard of airflow measurement. A typical air conditioning system produces 400 CFM per ton of air conditioning. |
| CHECK VALVE | A valve designed to permit flow in one direction only. |
| COIL | A heating or cooling element made of pipe or tubing, usually with plates or fins. |
| Combined Annual Efficiency (CAE) | A measure of the amount of heat produced for every dollar of fuel consumed for both home and water heating. |
| COMMISSIONING | The final step in installing a heating or air conditioning system. Every component is checked and tested for compliance with codes, manuals, manufacturer requirements, and occupant needs. After commissioning, the technician will: provide documentation of testing, provide all equipment manuals, and show the homeowner how to operate the system. |
| Communication Module | A component of a SunSource® Home Energy System that shows system status and environmental benefits in real time. |
| Composite Fan Blades | Blades that are manufactured with rugged materials and an exclusive angled design that improve operation and durability, even in the harshest environments. Used in select Lennox® outdoor air conditioner or heat pump units. |
| COMPRESSION | The reduction of volume of a vapor or gas by mechanical means. |
| COMPRESSION RATIO | The ratio determined by dividing the discharge pressure, in PSI (Pa), by the suction pressure in PSI (Pa). |
| Compressor | The part of an outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements. |
| CONDENSATION POINT | The temperature at which the removal of any heat will begin a change of state from a vapor to a liquid. |
| CONDENSER (HEAT EXCHANGER) | The outside unit of a heating or air conditioning system. Here the refrigerant condenses from a gas to a liquid and hot or cold air from the building is released to the outside. |
| Condenser Coil | The outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year. |
| CONDENSING MEDIUM | The substance, usually air or water, to which the heat in a condenser is transferred. |
| CONDENSING UNIT | The portion of a refrigeration system where the compression and condensation of refrigerant is accomplished. Sometimes referred to as the ‘high side’. |
| Condensing Unit | Every split system cooling system contains two parts: the indoor coil/furnace/air handler and the outdoor condensing unit. The condensing unit typically contains the compressor and condenser coil (among other things). |
| CONDUCTION | The transfer of heat from molecule to molecule within a substance. |
| CONTACTOR | An electromagnetic actuated relay. Usually used to refer to the relay which closes the circuit to a compressor. |
| Control | A temperature-control device, typically found on a wall inside the home. It consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system. American Standard Heating & Air Conditioning’s programmable controls allow you to program different levels of comfort for different times of the day. |
| CONVECTION | The transfer of heat by a moving fluid. |
| COOLING ANTICIPATOR | A resistance heater (usually not adjustable) in parallel with the cooling circuit. It is ‘on’ when the current is ‘off’, adding heat to shorten the off cycle. |
| COP | Coefficient of performance, an efficiency ratio that compares the amount of heat delivered to the amount of energy used. As with MPG on a car, the higher the score the more energy efficient the equipment is. |
| CUBIC FEET PER MINUTE | A common means of assigning quantitative values to volumes of air in transit, usually abbreviated CFM. |
| Cubic Feet Per Minute (CFM) | A measurement of how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being moved through the ductwork by the system. |
| CYCLE | The complete course of operation of a refrigerant back to a selected starting point in a system. |
| Cycling | Refers to the process of an HVAC system turning on and off. Some systems require less cycling than others, leading to higher energy efficiency and less wear on the system. |
| Damper | A movable plate, located in the ductwork, that regulates airflow and directs it to areas that need it most. Typically used in a zoning application. |
| Decibel (dB) | A unit used to measure the relative intensity of sound. |
| DEHUMIDIFIER | A device that removes excess moisture from the air. |
| Demand Flow Technology (DFT) | DFT is a process used by Westinghouse manufacturers to make sure that only the highest quality products leave the factory. The unit/part is checked at every part of the manufacturing process to make sure that the correct process was used prior to reaching that station. |
| DENSITY | Mass or weight per unit of volume. |
| Department Of Energy (DOE) | A federal agency responsible for setting industry efficiency standards and monitoring the consumption of energy sources. |
| DISCHARGE LINE | A tube used to convey the compressed refrigerant vapor from the compressor to the condenser inlet. |
| DISCHARGE PRESSURE | The pressure read at the compressor outlet. Also called head pressure or high side pressure. |
| DOE | The U.S. Department of Energy, the federal agency that sets industry efficiency standards. |
| Downflow | A type of furnace that takes cool air from the top and blows warm air to the bottom. Typically, downflow furnaces are installed in an attic. |
| DRY AIR | Air which contains no moisture vapor. |
| DRY BULB TEMPERATURE | Temperature read with an ordinary thermometer. |
| Dry-Charged Unit | An air-conditioner or heat pump that is shipped dry and charged with refrigerant at the place of installation. Dry-charged units are appropriate for homeowners who need a replacement unit compatible with R-22 refrigerant. |
| Dual Fuel | A comfort system that pairs an electric heat pump with a gas furnace and alternates between the two fuel sources to maximize comfort and efficiency. |
| DUCT | Conduits used to carry air. They can be round or rectangular, sheet metal or fiberglass or vinyl tubes. In air conditioning systems they carry air from the home to the air conditioning system or furnace and back to the home. |
| Ductwork | The air distribution system in your home is known as ductwork. Inside these hollow metal pipes air is either delivered to your rooms or returned to your system for conditioning or heating. |
| ecoLogic | This is Westinghouse’s designation for the greenest heating and cooling equipment. These units are exceptionally energy efficient, use earth-friendly R-410A refrigerant and contain additional home comfort features that make them at the peak of HVAC quality. |
| EER | EER is a measurement of cooling efficiency. Unlike SEER, EER is not the measure of cooling efficiency over a given season. EER is not typically used to label the efficiency of new cooling equipment. |
| EFFECTIVE TEMPERATURE | An arbitrary concept which combines into a single value the effect of temperature, humidity, and air movement as sensed by the human body. |
| Electronic Air Cleaner | Electronic air cleaners are electronic devices that filter our particles and contaminants in indoor air. |
| ENERGY STAR | High-efficiency heating and and air conditioning equipment is rated according to ENERGY STAR efficiency standards. |
| ENTHALPY | Total amount of heat in one pound (kg) of a substance calculated from accepted temperature base, expressed in BTU’s per pound mass (J/kg). |
| Environmental Protection Agency (EPA) | An agency of the U.S. government that develops and enforces federal environmental regulations and oversees the nationwide ENERGY STAR® program. |
| EPA | The U.S. Environmental Protection Agency. |
| EQUIVALENT LENGTH | That length of straight tubing which has the same pressure drop as the fitting, valve or accessory (of the same nominal size) being considered. |
| ERV | Energy Recovery Ventilator, a machine that draws fresh air into the home and exhausts stale air from the home. It uses a process to preheat or pre-cool (depending on the season) to reduce energy costs associated with conditioning the air. |
| EVAPORATIVE COOLING | The cooling effect of vaporization of a liquid in a moving air stream. |
| EVAPORATOR | A device in which a liquid refrigerant is vaporized. Some super-heating usually takes place. |
| Evaporator Coil | The part of an air conditioner or heat pump that absorb the heat from the air in your house. It is located inside the air handler or attached to the furnace. |
| EVAPORATOR SUPERHEAT | The actual temperature of the refrigerant vapor at the evaporator exit as compared to the saturated vapor temperature indicated by the suction pressure. |
| EXTERNAL STATIC PRESSURE | The sum of the static and velocity pressures of a moving air system at the point of measurement. |
| FAHRENHEIT | A temperature scale with the freezing point of water 32 oF and the boiling point 212 oF at sea level. |
| FEET PER MINUTE | A term assigned to a velocity of a moving air stream, usually express FPM. |
| FILTER-DRIER | A device that removes moisture, acid and foreign matter from the refrigerant. |
| Fixed Speed | Fixed-speed motors are the industry standard for heating and cooling equipment. Fixed-speed units maintain consistent airflow. |
| FLASH GAS | Instantaneous evaporation of some liquid refrigerant at the metering device due to pressure drop which cools the remaining liquid refrigerant to desired evaporation temperature. |
| Formicary Corrosion | A type of corrosion caused by the combination of organic acids, water, oxygen and copper. This form of corrosion is particularly problematic for homeowner in high-moisture environments and is the leading cause of coil leaks. |
| FREEZING POINT | The temperature at which the removal of any heat will begin a change of state from a liquid to a solid. |
| FURNACE | A self-contained heating unit that is designed to deliver heated air to a home. |
| Garage Heaters | Natural or propane gas units that provide warmth for car garages of almost any size during the winter months. Separated combustion models provide heating for hard-to-heat applications. |
| Gas Pack | A packaged heating and cooling unit that contains all of the components of a furnace and an air conditioner. |
| GAUGE PRESSURE | Pressure measured with atmospheric pressure as a base. |
| Genuine Contractor | The top tier of contractor quality as designated by Westinghouse. These contractors offer extended warranty coverage, are up-to-date on the latest training and certifications, maintain positive reviews with homeowners, and more. |
| Grid-Tied System | The most common and least expensive of all residential solar systems. Allows homeowners to use their own solar-generated electricity to save energy and reduce costs. The utility company’s grid, or network of power stations, serves as the backup power source. |
| HCFC | Hydrochlorofluorocarbons, used as a refrigerant in air conditioners and heat pumps. HCFCs were thought to contribute to the depletion of the earth�s ozone layer. |
| HEAT | A form of energy causing the agitation of molecules within a substance. |
| HEAT EXCHANGER | 1. The part of a furnace that transfers heat from burning fuel to the air used to heat your home. Also, from a boiler to water for hydronic heating.\n 2. A device, such as a condenser or evaporator, in which heat is added or removed in order to heat or cool your home. |
| Heat Exchanger | The main part of the furnace that transfers heat into the air in your furnace, which is then distributed throughout your home through your ductwork. |
| HEAT FLOW | Heat flows from a warmer to a cooler substance. The rate depends upon the temperature difference, the area exposed and the type of material. |
| HEAT OF COMPRESSION | The heat added to a vapor by the work done on it during compression. |
| HEAT OF THE LIQUID | The increase in total heat (Enthalpy) per pound of a saturated liquid as its temperature is increased above a chosen base temperature. (Usually – 40 oF for refrigerants). |
| Heat Pump | An HVAC unit that heats or cools by moving heat. During the winter, a heat pump draws heat from outdoor air and circulates it through a home’s air ducts. In the summer, it reverses the process and removes heat from the house and releases it outdoors. |
| HEAT TRANSFER | The three methods of heat transfer are conduction, convection and radiation. |
| Heating Seasonal Performance Factor (HSPF) | The heating efficiency rating for heat pumps. The higher the rating, the more efficient the heat pump. |
| HEPA Filter | A High Efficiency Particulate Absorbing filter. A HEPA filter removes particles from the air by trapping them as air flows through. |
| HEPA Filter | HEPA stands for ‘High-Efficiency Particulate Absorption’ and is a standard for the most effective air filters. HEPA filters are high-efficiency filters that block the tiniest particles from entering your home. Westinghouse includes these filters in our HEPA air cleaners. |
| HFC | Hydroflorocarbon, used as a refrigerant in air conditioners and heat pumps. It has little or no effect on the ozone layer. |
| Home Automation | Anything that gives you remote or automatic control of things around your home, including but not limited to your HVAC, lighting or security system. |
| Horizontal Flow | Describes an air handler or furnace that is positioned on its side and circulates air in one end and out the other. Ideal for attic or crawl space installations. |
| Horizontal Flow | A type of furnace, installed on its side, which draws air from one side, heats the air and then sends it out the other side. |
| HRV | Heat Recovery Ventilator, a machine that brings fresh air into a home through a process that preheats the air so it has less impact on your utility bill. |
| HSPF | Heating Seasonal Performance Factor. Refers to the efficiency of the heating mode of heat pumps over an entire heating season: The higher the number, the more efficient the unit. |
| HSPF | Heating Seasonal Performance Factor, an equipment efficiency rating. As with MPG on a car, the higher the rating the more fuel efficient the equipment is. |
| Humidifier | An indoor air quality product that adds moisture to heated air as it passes from the furnace into the ductwork for distribution throughout the home. |
| Humidistat | An automatic device used to maintain humidity at a fixed or adjustable set point. |
| Humidity | Humidity is an indication of the amount of moisture in a given volume of air. In HVAC, humidity levels are measured in terms of relative humidity (the amount of moisture in the air expressed as a percentage of how much water can be in a volume of air at a particular temperature). |
| HVAC | The classic acronym for Heating, Ventilation and Air Conditioning. Today, an HVAC system also includes air cleaning and moisture control. |
| HVACR | Heating, ventilating, air conditioning, and refrigeration |
| Hybrid Comfort System | A home comfort system that combines a heat pump with a gas furnace (also available in packaged systems). For areas with colder temperatures, combining electric heating (heat pump) with gas heating (furnace) lets you choose from two fuel sources in order to respond to fluctuations in utility costs. |
| IAQ | IAQ stands for ‘Indoor Air Quality’ and is the combination of air cleaners, humidifiers, filters, etc. that help improve the quality of your indoor air. |
| INCHES OF MERCURY | Atmospheric pressure is equal to 29.92 inches of mercury. |
| Indoor Coil | The other, less visible half of your outdoor unit. It’s attached to your furnace or air handler. As indoor air flows across it, heat and moisture are drawn out, leaving air that is cool, comfortable and conditioned. |
| Indoor/Outdoor System | Refers to a comfort system consisting of components in two locations. Common examples include an outside unit, such as an air conditioner, and an indoor unit, such as a furnace with a coil. |
| INFILTRATION | Air that enters your home through holes, gaps, and cracks, (e.g., plumbing or electrical holes, the heating and air conditioning system, doors, and windows). |
| Interconnection Agreement | See Net Metering. |
| Inverter | Inverters in Westinghouse’s heating and air conditioning equipment work in tandem with a rotary compressor in order to provide some of the most efficient operation in the industry. This inverter converts AC current into DC current and allows a unit to modulate at almost infinite capacities. This technology is crucial for the high-efficiency performance of Westinghouse’s iQ Drive line of products. |
| iQ Drive | This is a line of products that is at the peak of efficiency and quality. iQ Drive products employ temperature modulation for energy-efficient performance and include air conditioner, heat pumps, air handlers and furnaces. These units also include additional home comfort and noise reduction features for premium, quiet performance. |
| ISO 9000 | A family of international standards for quality management and assurance. |
| LATENT HEAT | Heat that produces a change of state without a change in temperature; i.e., ice to water at 32 oF or water to steam at 212 oF. |
| LATENT HEAT OF CONDENSATION | The amount of heat energy in BTU’s that must be removed to change the state of one pound of a vapor to one pound of liquid at the same temperature. |
| LATENT HEAT OF FUSION | The amount of heat energy, in BTU’s required to change the state of one pound of a liquid to one pound of solid at the same temperature. |
| LATENT HEAT OF MELTING | The amount of heat energy, in BTU’S, that must be removed to change the state of one pound of solid to one pound of liquid at the same temperature. |
| LATENT HEAT OF VAPORIZATION | The amount of heat energy in BTU’s required to change the state of one pound of a liquid to one pound of vapor at the same temperature. |
| LIFT | To elevate a fluid from one level to a higher level. |
| Lineset | The lineset is the component of your central cooling system that circulates the refrigerant through the various, crucial components. |
| LIQUID LINE | A tube used to convey the liquid refrigerant from the condenser outlet to the refrigerant control device of the evaporator. |
| Load Calculation | A detailed analysis of your home’s energy needs conducted by your dealer to help determine which comfort system is best for your home. |
| MANOMETER | A tube filled with a liquid used to measure pressures. |
| Matched System | A heating and cooling system wherein all components are matched in capacity and efficiency. This enables your system to perform at its best, and most efficient, for longer. |
| MBH | One MBH is equivalent to 1,000 BTU’s per hour. |
| MEAN TEMPERATURE DIFFERENCES | The mean of difference between the temperature of a fluid receiving and a fluid yielding heat. |
| Media Filter | A media filter catches all of the harmful particulates in your indoor air and is located in air cleaners. A media filter’s effectiveness is measured in microns. |
| MELTING POINT | The temperature at which the addition of any heat will begin a change of state from a solid to a liquid. |
| MERCURY MANOMETER | Used to measure vacuum in inches of mercury. |
| MERV Rating | Minimum Efficiency Reporting Value, describes the size of the holes in the filter that allow air to pass through. The higher the MERV rating, the smaller the holes in the filter, and the higher the efficiency. |
| Micro-Channel | Micro-Channel is a specific design used in coils to help combat formicary corrosion and reduce the overall weight of the unit. All-aluminum Micro-Channel coils are the most resistant against formicary corrosion. In addition, this technology requires less refrigerant and facilitates better heat transfer. |
| Micron | A unit of measure equal to one millionth of a meter, or one thousandth of a millimeter. |
| Modulating Heating | Fully modulating heating provides greater fuel efficiency and ideal comfort control by constantly adjusting to changing temperatures in your home. |
| MOLD | A natural byproduct of the fungi family that thrives when organic substances and water combine under certain circumstances. Mold reproduces via spores that can remain dormant, yet viable, for years. Many molds are beneficial. For example, they are the bleu in bleu cheese, and we use them to make wine, penicillin, and antibiotics. However, some molds can cause health problems. |
| MOLLIER CHART | A psychrometric chart. How-to convert between Mollier and Psyhrometric charts? |
| MUFFLER | Device installed in hot gas line to silence discharge surges. |
| NATE | North American Technician Excellence. This is the nationwide certification program for home heating and cooling technicians. It’s the only certification that is recognized by the entire industry. |
| Net Metering | A service available from many utility providers in which homeowners get full retail value for most, if not all, of the electricity produced by their own generating system, such as a SunSource® Home Energy System. A utility meter keeps track of the “net” difference between the electricity used from the utility provider and the electricity produced by the homeowner’s system. |
| Off-Grid Or Off-The-Grid | An electricity-generating system that operates independently from the utility grid, providing all of the electricity needed in the home, and are generally more expensive than grid-tied systems. Ideal for homes located in remote areas without utility service, or where installing power lines would be extremely costly. |
| OIL SEPARATOR | A device for separating out oil entrained in the discharge gas from the compressor and returning it to the crankcase. |
| Outdoor Coil | See Condenser Coil. |
| Outdoor Unit | The outdoor portion of a split system, such as an air conditioner or heat pump. May also be a packaged air conditioning and/or heating system in which all components are located in one cabinet. |
| Packaged System | An air conditioning and/or heating system in which all components are located 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. |
| Packaged Unit | A heating and cooling system contained in one outdoor unit. |
| PARTIAL PRESSURE | The pressure exerted by any individual gas in a mixture. |
| Particles | Any substances measuring less than 100 microns in diameter. The U.S. EPA has found that particles less than 2.5 microns are responsible for the health effects of greatest concern. |
| PITCH | The slope of a pipe line for the purpose of improving drainage. |
| PITOT TUBE | A device comprising a small diameter orifice projecting directly into an air stream measuring total pressure and surrounded by an annular section with small diameter entrances normal to the flow, measuring static pressure; both sections are usually connected to a manometer to indicate velocity pressure. |
| PRECHARGED LINES | Refrigerant line’s which are filled with refrigerant and are sealed at both ends. The seals are broken when the lines are installed and the line charge becomes part of the total system charge. |
| PRESSURE – TEMPERATURE RELATIONSHIP | The change effected in temperature when pressure is changed or vice versa. Only used at saturated conditions. An increase in pressure results in a temperature increase. A decrease in temperature results in a pressure decrease. |
| PRESSURE DROP | The decrease in pressure due to friction of a fluid or vapor as it passes through a tube or duct or/and lift. |
| Programmable Thermostat | A thermostat with the ability to record different temperature/time settings for home heating and/or cooling equipment. |
| PSYCHROMETER | A devices having both a dry and wet bulb thermometer. It is used to determine the relative humidity in a conditioned space. Most have an indexed scale to allow direct conversion from the temperature readings to the percentage of relative humidity. |
| PSYCHROMETRIC CHART | A chart on which can be found the properties of air under varying conditions of temperature, water vapor content, volume, etc. |
| PUMPDOWN | Process of pumping refrigerant out of the evaporator and suction line at the end of the on- cycle by closing a solenoid valve in the liquid line and letting the compressor shut-off by the low pressure control. |
| QUICK CONNECT | Name given to the end connections on precharged lines which screw on to mated fittings of the outdoor and indoor sections. Tightening the quick connections ruptures the seals on the fittings and the line charge becomes part of the total system charge. |
| R-22 | R-22 is a type of refrigerant that has been used over the years in cooling equipment. Recently, it has been deemed harmful to the environment, due to its status as an HCFC, and is being phased out and replaced by R-410A refrigerant. R-22 is also known as ‘Freon.’ |
| R-22 Refrigerant | The old standard for residential air conditioners, now being phased out by the U.S. EPA. Lennox offers dry-charged units for those who still have R-22 compatible systems. |
| R-410A | The refrigerant that replaces R-22. It does not contain chlorine and is not hazardous to the environment. |
| R-410A Refrigerant | A chlorine-free refrigerant that meets the U.S. EPA’s newest, most stringent environmental guidelines. |
| RADIATION | The transfer of heat without an intervening medium. It is absorbed on contact with a solid surface. |
| RECEIVER | A vessel for holding refrigerant liquefied by the condenser. |
| Refrigerant | A chemical that produces a cooling effect while expanding or vaporizing. Most residential air conditioning units contain the standard R-22 refrigerant, or Freon. |
| REFRIGERANT CHARGE | The procedure an HVACR technician performs to ensure that the system has enough of the right kind refrigerant for peak operating performance. |
| REFRIGERANT CONTROL | A device used to meter the amount of refrigerant to an evaporator. It also serves as a dividing point between the high and low pressure sides of the system. |
| REFRIGERANT DISTRIBUTOR | A device which meters equal quantities of refrigerant to independent circuits in the evaporator coil. |
| Refrigerant Lines | Two copper lines that connect the outdoor air conditioner or heat pump to the indoor evaporator coil. |
| REFRIGERANT MIGRATION | The movement of refrigerant through the system to the compressor crankcase during the off-cycle, caused by its attraction to oil. |
| REFRIGERANT OPERATING CHARGE | The total amount of refrigerant required by a a system for correct operation. |
| REFRIGERANT VELOCITY | The rate at which refrigerant is moving at a given point in a system, usually given in feet per minute (FPM). |
| REFRIGERATION | The transfer of heat from a place where it is not wanted to a place where its presence is not undesirable. |
| REFRIGERATION EFFECT | The amount of heat a given quantity of refrigerant will absorb in changing from a liquid to a vapor at a given evaporating pressure. |
| RELATIVE HUMIDITY | The percentage of water vapor present in a given quantity air compared to the amount it can hold at its temperature. |
| RELAY | A device used to open and close an electrical circuit. The relay may may be actuated by a bimetal electrically heated strip, a rod wrapped with a fine resistance wire causing expansion when energized, a bellows actuated by expansion of a fluid or gas or an electromagnetic coil. |
| RETURN, RETURN AIR, RETURN SIDE | The path the air takes to get to an air-handling unit or furnace so it can be cooled or heated. It is the return path. The return side should be balanced with the supply side to ensure proper air flow and comfort. |
| REVERSING VALVE | A device in a heat pump that is electrically controlled to reverse the flow of refrigerant as the system is switched from cooling to heating; also called a four-way valve. |
| RISER | A vertical tube or pipe which carries refrigerant in any form from a lower to a higher level. |
| Rotary Compressor | A rotary compressor works like any other compressor – its job is to compress refrigerant, raising the temperature and pressure. Unlike a scroll compressor, a rotary compressor achieves compression with a roller. Typically, a rotary compressor is viewed as less efficient (when not paired with an inverter). |
| SATURATED VAPOR | Vapor in contact with a liquid. |
| SATURATION | A condition of stable equilibrium of a vapor and a liquid. |
| Scroll Compressor | The scroll compressor is a type of compressor that is typically considered the more efficient, quiet compressor. It spirals inside its cabinet in order to raise the pressure and, thereby, the temperature of the refrigerant as it passes through the outdoor condensing unit. |
| Seasonal Energy Efficiency Ratio (SEER) | Seasonal Energy Efficiency Ratio, an energy efficiency rating for air conditioners. The higher the SEER, the more efficient the unit. |
| SEER | Seasonal Energy Efficiency Ratio. This is a rating that measures the cooling efficiency of a heat pump or air conditioner. The higher the number, the more efficient the unit. |
| SEER 13 | This is the new minimum efficiency standard (effective January 2006) for an air conditioner or heat pump. All new units must now meet this standard. Previously manufactured equipment may be used, sold, and installed. SEER is defined later. |
| SEET | Seasonal Extreme Environmental Test. This is the American Standard testing facility for heating and air conditioning systems, where the equivalent of five years of operation is condensed into 16 weeks of testing under harsh conditions. American Standard Heating & Air Conditioning wants to ensure your new system will be as reliable as possible. |
| SENSIBLE HEAT | Heat that can be measured or felt. Sensible heat always causes a temperature rise. |
| SIGHT GLASS | A glass installed in the liquid line permitting visual inspection of the liquid refrigerant for the purpose of detecting vapor in the liquid. They also generally have a device included to monitor moisture content of the refrigerant. |
| Single-Stage | Basic heating and air conditioning units operate in one stage. This is the basic system setup. |
| SLUGGING | A condition in which a quantity of liquid enters the compressor causing hammering and possible compressor damage. |
| Smart Home | A smart home features an advanced system that offers remote or automatic control of the systems around your home, including but not limited to, your HVAC system, lighting or security system. |
| SPECIFIC HEAT | The amount of heat necessary to change the temperature of one pound of a substance 10 F. |
| SPECIFIC VOLUME | The volume of a substance per unit of mass; i.e., standard air 13.33 cubic feet per pound. The reciprocal of density. |
| Split System | A heating and cooling system that includes an indoor unit, outdoor unit and a thermostat. |
| STANDARD AIR DENSITY | 0.075 pounds per cubic foot. Equivalent to dry air at 70 oF and at sea level pressure. |
| STATE CONDITION | Substances can exist in three states – solid, liquid or vapor. |
| STATIC PRESSURE | The normal force per unit area at a small hole in the wall of a duct. |
| STATIC TAP | A means by which static pressures of a duct system may be read directly, usually consisting of a small diameter hole in the side of the duct connected to a manometer. |
| SUB COOLING | Cooling of a liquid, at a constant pressure, below the point at which it was condensed. |
| SUBLIMATION | A condition where a substance changes from a solid to a gas without becoming a liquid. |
| SUCTION LINE | A tube used to convey the refrigerant vapor from the evaporator outlet to the suction inlet of compressor. |
| SUCTION LINE ACCUMULATOR | A device located in the suction line that intercepts quantities of a liquid refrigerant and thereby prevents damage to the compressor. |
| SUPERHEAT | Heat added to a vapor after all liquid has been vaporized. |
| SUPPLY or SUPPLY SIDE | The part of an HVAC system that takes (supplies) the conditioned air from the air-handling unit or furnace to your home. The supply side should be balanced with the return side to ensure proper air flow and comfort. |
| TEMPERATURE | A measurement of heat intensity. |
| Thermidistat | A unit that monitors temperature and humidity and adjusts heating or cooling system to maintain desired levels. |
| THERMISTOR | Basically a semiconductor which has electrical resistance that varies inversely with temperature. |
| Thermostat | A unit that allows homeowners to monitor and adjust heating and cooling equipment. |
| THERMOSTATIC EXPANSION VALVE | Refrigerant control which monitors the flow rate according to the superheat at the evaporator outlet. |
| Ton | Unit of measurement for determining cooling capacity. One ton equals 12,000 Btuh. |
| Ton | A unit of measurement used for determining cooling capacity. One ton is the equivalent of 12,000 BTUs per hour. |
| Ton (of air conditioning) | A ton of air conditioning refers to capacity in relation to melting one ton of ice in 24 hours. The capacity is measured in British Thermal Units (BTU): 288,000 BTU are required to melt one tone of ice in 24 hours (or 12,000 BTU/hr). A 2-ton air conditioner has a nominal capacity of about 24,000 BTU/h. |
| TON OF REFRIGERATION | The amount of heat of fusion absorbed by melting 1 short ton (0.893 long ton or 0.907 t) of pure ice at 0 °C (32 °F) in 24 hours. Equivalent to the consumption of one ton of ice per day during the transition from stored natural ice to mechanical refrigeration. |
| TOTAL HEAT (Enthalpy) | Total heat energy in a substance. The sum of sensible and latent heat. |
| TOTAL PRESSURE | The sum of all partial pressures in a mixture of gases. |
| TRAP | A depression or dip in refrigerant piping in which oil will collect. A trap may be placed at the base of a suction or hot gas riser to improve oil return up the riser. |
| Two-Stage | Two-Stage HVAC systems are just as efficient as single-stage systems – the difference is in comfort level. These units have two different capacities: a higher capacity and a lower capacity. Two-stage systems are able to operate longer at the lower capacity, allowing for a better mix of air and quieter operation. |
| Two-stage Heating / Two-stage Cooling | Two-stage heating and cooling is considered to be more efficient, because it operates at a low, energy-saving speed most of the time. However, on days when more heating or cooling is required, it switches to the next stage for maximum comfort. |
| Two-Stage Operation | Provides two levels of heating or cooling output for enhanced temperature control, energy efficiency and indoor air quality. |
| Upflow | A type of furnace that draws cool air from the bottom and blows the warmed air out the top. Typically, these furnaces are installed in basements. |
| UV Light Systems | For maximum air cleanliness, a UV light system uses the UV light spectrum to kill and control airborne microbes. |
| VACUUM | Any pressure below atmospheric pressure. |
| VAPOR BARRIER | The term applied to an impervious layer of material superimposed upon a layer of insulation. Vapor barriers are always applied on the warm side of the insulation layer. |
| VAPOR PRESSURE | The pressure exerted by vapor. |
| VARIABLE FREQUENCY DRIVE (VFD) | Automated speed control for electric motors like fans, pumps and centrifugal chillers for precise control and energy savings |
| Variable-Speed Motor | The fan motor inside higher efficiency indoor and outdoor units is designed to change its speed based on your home’s heating and air conditioning requirements. Working in conjunction with your thermostat, it keeps the appropriate-temperature air (e.g., warm air on cold days) circulating throughout your home, reducing temperature variances. The variable-speed motor also increases dehumidification and is quiet because it runs at a lower speed most of the time. Plus, the consistent air circulation eliminates noisy startups and shutdowns. |
| VELOCITY PRESSURE | In a moving fluid, the pressure capable of causing an equivalent velocity as applied to move the same fluid through an orifice such that all pressure energy expanded is converted into kinetic energy. |
| Ventilator | A system that exchanges stale, recirculated indoor air with fresh, filtered outside air. |
| WATER MANOMETER | Used to measure pressure in inches of water. |
| WET BULB TEMPERATURE | Temperature read with a thermometer whose bulb is encased in a wetted wick. |
| Zone | Zoning allows you to control the heating and cooling delivered to specific areas of your house for a custom solution. Zoning can increase efficiency and comfort in the area of the house you use most often. Pair a zoning system with a programmable thermostat to set a reliable comfort schedule. |
| ZONES, ZONED SYSTEM, ZONING | A single HVAC system that can meet different heating and cooling needs in different areas (zones). Each zone of a home has its own thermostat with which it can regulate the temperature and humidity in its area. One zoned air conditioner could be set for a high temperature in one zone and for a lower temperature in the other zone. Zone systems have two or more zones. |
| Zoning System | A heating and cooling system that creates customized temperature zones throughout the home for increased comfort and efficiency. |