what is air conditioner

Upload: muhammad-nuaim

Post on 03-Apr-2018

225 views

Category:

Documents


0 download

TRANSCRIPT

  • 7/29/2019 what is air conditioner

    1/13

    What is Air Conditioner??

    Air conditioning are the process of altering the properties ofair (primarily temperature and

    humidity) to more favorable conditions. More generally, air conditioning can refer to any

    form of technological cooling, heating, ventilation, or disinfection that modifies the condition

    of air.

    An air conditioner (often referred to as AC) is a major or home appliance, system, or

    mechanism designed to change the air temperature and humidity within an area (used for

    cooling and sometimes heating depending on the air properties at a given time). The cooling

    is typically done using a simple refrigeration cycle, but sometimes evaporation is used,

    commonly for comfort cooling in buildings and motor vehicles. In construction, a complete

    system of heating, ventilation and air conditioning is referred to as "HVAC".

    The basic concept behind air conditioning is known to have been applied in ancient Egypt

    where reeds hung in windows had water trickling down. The evaporation of water cooled the

    air blowing through the window, though this process also made the air more humid. InAncient Rome, water from aqueducts was circulated through the walls of certain houses to

    cool them down. Other techniques in medieval Persia involved the use ofcisterns and wind

    towers to cool buildings during the hot season. Modern air conditioning emerged from

    advances in chemistry during the 19th century, and the first large-scale electrical air

    conditioning was invented and used in 1902 by Willis Haviland Carrier. The introduction in

    America of residential air conditioning in the 1920s helped start the great migration to the

    Sun Belt.

    The History

    In 1902, the first modern electrical air conditioning unit was invented by Willis Haviland

    Carrier in Buffalo, New York. After graduating from Cornell University, Carrier, a native of

    Angola, New York, found a job at the Buffalo Forge Company. While there, Carrier began

    experimenting with air conditioning as a way to solve an application problem for the Sackett-

    Wilhelms Lithographing and Publishing Company in Brooklyn, New York, and the first "air

    conditioner", designed and built in Buffalo by Carrier, began working on 17 July 1902.

    Designed to improve manufacturing process control in a printing plant, Carrier's invention

    controlled not only temperature but also humidity. Carrier used his knowledge of the heatingof objects with steam and reversed the process. Instead of sending air through hot coils, he

    sent it through cold coils (ones filled with cold water). The air blowing over the cold coils

    cooled the air, and one could thereby control the amount of moisture the colder air could

    hold. In turn, the humidity in the room could be controlled. The low heat and humidity helped

    maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was

    applied to increase productivity in the workplace, and The Carrier Air Conditioning

    Company of America was formed to meet rising demand. Over time, air conditioning came to

    be used to improve comfort in homes and automobiles as well. Residential sales expanded

    dramatically in the 1950s.

    In 1906, Stuart W. Cramer ofCharlotte, North Carolina was exploring ways to add moistureto the air in his textile mill. Cramer coined the term "air conditioning", using it in a patent

    http://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Disinfectionhttp://en.wikipedia.org/wiki/Major_appliancehttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Mechanism_%28technology%29http://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Ventilation_%28architecture%29http://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Ancient_Romehttp://en.wikipedia.org/wiki/Aqueducthttp://en.wikipedia.org/wiki/Persiahttp://en.wikipedia.org/wiki/Cisternhttp://en.wikipedia.org/wiki/Wind_towerhttp://en.wikipedia.org/wiki/Wind_towerhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/United_States_of_Americahttp://en.wikipedia.org/wiki/Sun_Belthttp://en.wikipedia.org/wiki/Inventionhttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/Buffalo,_New_Yorkhttp://en.wikipedia.org/wiki/Cornell_Universityhttp://en.wikipedia.org/wiki/Angola,_New_Yorkhttp://en.wikipedia.org/wiki/Buffalo_Forge_Companyhttp://en.wikipedia.org/wiki/Brooklyn,_New_Yorkhttp://en.wikipedia.org/wiki/Printinghttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Carrier_Corporationhttp://en.wikipedia.org/wiki/Carrier_Corporationhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Stuart_W._Cramerhttp://en.wikipedia.org/wiki/Charlotte,_North_Carolinahttp://en.wikipedia.org/wiki/Charlotte,_North_Carolinahttp://en.wikipedia.org/wiki/Stuart_W._Cramerhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Carrier_Corporationhttp://en.wikipedia.org/wiki/Carrier_Corporationhttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Printinghttp://en.wikipedia.org/wiki/Brooklyn,_New_Yorkhttp://en.wikipedia.org/wiki/Buffalo_Forge_Companyhttp://en.wikipedia.org/wiki/Angola,_New_Yorkhttp://en.wikipedia.org/wiki/Cornell_Universityhttp://en.wikipedia.org/wiki/Buffalo,_New_Yorkhttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/Inventionhttp://en.wikipedia.org/wiki/Sun_Belthttp://en.wikipedia.org/wiki/United_States_of_Americahttp://en.wikipedia.org/wiki/Willis_Haviland_Carrierhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Wind_towerhttp://en.wikipedia.org/wiki/Wind_towerhttp://en.wikipedia.org/wiki/Cisternhttp://en.wikipedia.org/wiki/Persiahttp://en.wikipedia.org/wiki/Aqueducthttp://en.wikipedia.org/wiki/Ancient_Romehttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Ventilation_%28architecture%29http://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Evaporative_coolerhttp://en.wikipedia.org/wiki/Refrigeration_cyclehttp://en.wikipedia.org/wiki/Mechanism_%28technology%29http://en.wikipedia.org/wiki/Systemhttp://en.wikipedia.org/wiki/Home_appliancehttp://en.wikipedia.org/wiki/Major_appliancehttp://en.wikipedia.org/wiki/Disinfectionhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Air
  • 7/29/2019 what is air conditioner

    2/13

    claim he filed that year as an analogue to "water conditioning", then a well-known process for

    making textiles easier to process. He combined moisture with ventilation to "condition" and

    change the air in the factories, controlling the humidity so necessary in textile plants. Willis

    Carrier adopted the term and incorporated it into the name of his company. The evaporation

    of water in air, to provide a cooling effect, is now known as evaporative cooling.

    How its work?/

    How Does Air Conditioning WorkAs with all air conditioning systems the principle remains the same whereby the heat is removed from one areaand replaced with chilled dry air and the hot air is expelled, normally to the outside atmosphere. As you can seefrom this typical example of a air conditioning system, the ambient air is drawn over the condensor that can bestdescribed as a radiator as seen on motor vehicles but instead of water running through the system it contains a

    refrigerant gas.On its journey around the system it has three main stages; the evaporator contains the sub-cooled refrigerantand air blows through its veins to release the chilled dry air into the room, the condenser contains the hightemperature gas that once again air is blown through the veins collecting the heat as it passes through and this isthen expelled outside.

    Basic OperationsAn air conditioner is able to cool a building because it removes heat from the indoor air and transfers it outdoors.A chemical refrigerant in the system absorbs the unwanted heat and pumps it through a system of piping to theoutside coil. The fan, located in the outside unit, blows outside air over the hot coil, transferring heat from therefrigerant to the outdoor air.

    Most air conditioning systems have five mechanical components:compressorcondensoranevaporatorcoilblowera chemical refrigerant

    Most central air conditioning units operate by means of a split system. That is, they consist of a hot side, or thecondensing unitincluding the condensing coil, the compressor and the fanwhich is situated outside yourhome, and a cold side that is located inside your home. The cold side consists of an expansion valve and a coldcoil, and it is usually part of your furnace or some type of air handler. The furnace blows air through anevaporator coil, which cools the air. Then this cool air is routed throughout your home by means of a series of airducts. A window unit operates on the same principal, the only difference being that both the hot side and the coldside are located within the same housing unit.The compressor (which is controlled by the thermostat) is the heart of the system. The compressor acts as thepump, causing the refrigerant to flow through the system. Its job is to draw in a low-pressure, low-temperature,refrigerant in a gaseous state and by compressing this gas, raise the pressure and temperature of the refrigerant.This high-pressure, high-temperature gas then flows to the condenser coil.The condenser coil is a series of piping with a fan that draws outside air across the coil. As the refrigerant passesthrough the condenser coil and the cooler outside air passes across the coil, the air absorbs heat from therefrigerant which causes the refrigerant to condense from a gas to a liquid state. The high-pressure, high-temperature liquid then reaches the expansion valve.The evaporator coil is a series of piping connected to a furnace or air handler that blows indoor air across it,causing the coil to absorb heat from the air. The cooled air is then delivered to the house through ducting. Therefrigerant then flows back to the compressor where the cycle starts over again.

    http://en.wikipedia.org/wiki/Evaporative_coolinghttp://en.wikipedia.org/wiki/Evaporative_cooling
  • 7/29/2019 what is air conditioner

    3/13

    A simple stylized diagram of the refrigeration cycle:

    1) condensing coil,

    2) expansion valve,

    3) evaporator coil,

    4) compressor

    Refrigeration cycle

    Condenser

    http://en.wikipedia.org/wiki/Condensing_coilhttp://en.wikipedia.org/wiki/Thermal_expansion_valvehttp://en.wikipedia.org/wiki/Evaporator_coilhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/File:Heatpump.svghttp://en.wikipedia.org/wiki/File:Heatpump.svghttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Evaporator_coilhttp://en.wikipedia.org/wiki/Thermal_expansion_valvehttp://en.wikipedia.org/wiki/Condensing_coil
  • 7/29/2019 what is air conditioner

    4/13

    Capillary expansion valve connection to evaporator inlet. Noticefrostformation

    In the refrigeration cycle, a heat pump transfers heat from a lower-temperature heat source

    into a higher-temperature heat sink. Heat would naturally flow in the opposite direction. This

    is the most common type of air conditioning. A refrigerator works in much the same way, as

    it pumps the heat out of the interior and into the room in which it stands.

    This cycle takes advantage of the way phase changes work, where latent heat is released at a

    constant temperature during a liquid/gas phase change, and where varying the pressure of a

    pure substance also varies its condensation/boiling point.

    The most common refrigeration cycle uses an electric motor to drive a compressor. In an

    automobile, the compressor is driven by a belt over a pulley, the belt being driven by the

    engine's crankshaft (similar to the driving of the pulleys for the alternator, power steering,

    etc.). Whether in a car or building, both use electric fan motors for air circulation. Since

    evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air

    conditioners use a compressor to cause pressure changes between two compartments, and

    actively condense and pump a refrigerant around. A refrigerant is pumped into the evaporator

    coil, located in the compartment to be cooled, where the low pressure causes the refrigerant

    to evaporate into a vapor, taking heat with it. At the opposite side of the cycle is the

    condenser, which is located outside of the cooled compartment, where the refrigerant vapor is

    compressed and forced through another heat exchange coil, condensing the refrigerant into a

    liquid, thus rejecting the heat previously absorbed from the cooled space.

    Compressor

    The job of the compressor/condenser unit is to recompress warm

    refrigerant gas (pulled from the indoor air handler cooling coil) back to a

    liquid refrigerant that can be returned to the indoor cooling coil once again.

    When the room thermostat calls for cooling, both the indoor blower or airhandler and the outdoor compressor/condenser begin to work. Control

    http://en.wikipedia.org/wiki/Frosthttp://en.wikipedia.org/wiki/Frosthttp://en.wikipedia.org/wiki/Frosthttp://en.wikipedia.org/wiki/Heat_pumphttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Heat_sinkhttp://en.wikipedia.org/wiki/Refrigeratorhttp://en.wikipedia.org/wiki/Phase_transitionhttp://en.wikipedia.org/wiki/Latent_heathttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Belt_%28mechanical%29http://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Alternatorhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Evaporatorhttp://en.wikipedia.org/wiki/Heat_exchanger#HVAC_air_coilshttp://en.wikipedia.org/wiki/File:Capilliary_metering_device.jpghttp://en.wikipedia.org/wiki/Heat_exchanger#HVAC_air_coilshttp://en.wikipedia.org/wiki/Evaporatorhttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Power_steeringhttp://en.wikipedia.org/wiki/Alternatorhttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Pulleyhttp://en.wikipedia.org/wiki/Belt_%28mechanical%29http://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Latent_heathttp://en.wikipedia.org/wiki/Phase_transitionhttp://en.wikipedia.org/wiki/Refrigeratorhttp://en.wikipedia.org/wiki/Heat_sinkhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Heat_pumphttp://en.wikipedia.org/wiki/Frost
  • 7/29/2019 what is air conditioner

    5/13

    circuits and a contactor relay turn on the outside compressor/condenser

    motor and its outdoor cooling fan as well.

    The air conditioning or heat pump compressor compresses the incoming

    refrigerant to a high pressure gas and moves that gas into the condensingcoil described just below. Typically a piston moves up and down inside of a

    cylinder inside the compressor motor, drawing in refrigerant gas on the

    down stroke of the piston, and compressing the refrigerant gas on the up

    stroke of the piston. (Some refrigeration compressors such as those made

    by Frigidaire used a rotary compressor design that we found durable and

    powerful enough to lead us to salvage and re-use these motors for other

    purposes.

    The refrigerant gas leaves the compressor at high pressure and at hightemperature (since compressing a gas will raise its temperature). In most

    air conditioning or heat pump compressors, a piston moves up and down to

    draw in and then compress refrigerant gas, moving refrigerant vapor from

    the incoming low sideto the outgoing high sideof the compressor.

    The refrigerant gas leaving the compressor (and entering the condensing

    coil) will contain both heat that the refrigerant absorbed at the evaporator

    coil (heat from air in living space of the building), and additional heat

    produced at the compressor by the process of compressing the gas. Therefrigerant gas is thus heat ladenwithsensible heat(heat that we can

    measure) from the living area and compressor heat from the compressor

    motor.

    Evaporator

    The evaporator works the opposite of the condenser, here refrigerant liquid is converted

    to gas, absorbing heat from the air in the compartment.

    http://www.inspectapedia.com/aircond/aircond04.htm#HeatDefshttp://www.inspectapedia.com/aircond/aircond04.htm#HeatDefshttp://www.inspectapedia.com/aircond/aircond04.htm#HeatDefshttp://en.wikipedia.org/wiki/File:Embraco_compressor.jpghttp://www.inspectapedia.com/aircond/aircond04.htm#HeatDefs
  • 7/29/2019 what is air conditioner

    6/13

    Air conditioning evaporator works by absorb heat from the area (medium) that need tobe cooled. It does that by maintaining the evaporator coil at low temperature andpressure than the surrounding air.

    Since, the AC evaporator coil contains refrigerant that absorbs heat from thesurrounding air, the refrigerant temperature must be lower than the air.

    Theexpansion deviceprovides a pressure reduces between the high side and the lowside of the system, the saturation temperature of the refrigerant entering the airconditioning evaporator is lower than the medium to be cooled.

    One of the characteristic of anac refrigerantis that as the pressure is reduced theboiling point is also reduced. Therefore, as the pressure is reduced through theexpansion device so is the point at which it will boil and become a vapor.

    As the warm air from the space passes over the evaporator coil, it gives up its heat tothe lower temperature liquid/vapor mixture passing through the evaporator. As the liquid

    refrigerant absorbs this heat it boils changing from the liquid state to the vapor state.

    The amount of heat the air conditioner evaporator absorbs must equal the amount ofheat it lost

    For instance, if the air conditioning evaporator gives up 100 Btus of heat to the

    surrounding hot air, then the refrigerant within the air conditioning evaporator coil mustgain 100 Btus of heat.

    The amount of liquid entering the evaporator must be enough, so by the time it reachesthe end of the evaporator. It will be completely boiled to the vapor state.

    There must be enough air flows across the AC evaporator coil to provides heat to therefrigerant in the evaporator coil. This is just a safety way to ensure the air conditionercompressor doesnt have the liquid refrigerant entering it.

    Air conditioning evaporator picture above tells us what happen to the evaporator coil.

    http://www.central-air-conditioner-and-refrigeration.com/air_conditioner_expansion_valve.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air_conditioner_expansion_valve.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air_conditioner_expansion_valve.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air-conditioner-refrigerant.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air-conditioner-refrigerant.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air-conditioner-refrigerant.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air-conditioner-refrigerant.htmlhttp://www.central-air-conditioner-and-refrigeration.com/air_conditioner_expansion_valve.html
  • 7/29/2019 what is air conditioner

    7/13

    The evaporator coil absorbs heat into the refrigerant from the warmer air passing overthe surface of the evaporator coil. The heat absorbed causes the liquid refrigerant toboil, changing it from a liquid state to a vapor state.

    Blower

    Blower/fan

    Main articles:Mechanical fanandCentrifugal fan

    Air handlers typically employ a largesquirrel cage blowerdriven by an AC inductionelectric motorto

    move the air. The blower may operate at a single speed, offer a variety of set speeds, or be driven by

    aVariable Frequency Driveto allow a wide range ofair flowrates. Flow rate may also be controlled

    by inlet vanes or outlet dampers on the fan. Some residential air handlers (central "furnaces" or "air

    conditioners") use abrushless DC electric motorthat has variable speed capabilities.

    Multiple blowers may be present in large commercial air handling units, typically placed at the end ofthe AHU and the beginning of the supply ductwork (therefore also called "supply fans"). They are

    often augmented by fans in the return air duct ("return fans") pushing the air into the AHU.

    Controls

    Main articles:Building automationandBuilding management system

    Controlsare necessary to regulate every aspect of an air handler, such as:flow rate of air, supply air

    temperature, mixed air temperature, humidity, air quality. They may be as simple as an

    off/onthermostator as complex as abuilding automationsystem usingBACnetorLonWorks, for

    example.

    Common control components include temperature sensors, humidity sensors, sail

    switches,actuators, motors, and controllers.

    System

    Chilled water system

    Although standard air conditioners are very popular, they can use a lot of energy and generate quite a

    bit of heat. For large installations like office buildings, air handling and conditioning is sometimes

    managed a little differently.

    Some systems usewateras part of the cooling process. The two most well-known are chilled water

    systems and cooling tower air conditioners.

    Chilled water systems - In a chilled-water system, the entire air conditioner is installed on the roof orbehind the building. It cools water to between 40 and 45 degrees Fahrenheit (4.4 and 7.2 degrees

    http://en.wikipedia.org/wiki/Mechanical_fanhttp://en.wikipedia.org/wiki/Mechanical_fanhttp://en.wikipedia.org/wiki/Mechanical_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Variable_Frequency_Drivehttp://en.wikipedia.org/wiki/Variable_Frequency_Drivehttp://en.wikipedia.org/wiki/Variable_Frequency_Drivehttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Brushless_DC_electric_motorhttp://en.wikipedia.org/wiki/Brushless_DC_electric_motorhttp://en.wikipedia.org/wiki/Brushless_DC_electric_motorhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_management_systemhttp://en.wikipedia.org/wiki/Building_management_systemhttp://en.wikipedia.org/wiki/Building_management_systemhttp://en.wikipedia.org/wiki/HVAC_control_systemhttp://en.wikipedia.org/wiki/HVAC_control_systemhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/BACnethttp://en.wikipedia.org/wiki/BACnethttp://en.wikipedia.org/wiki/BACnethttp://en.wikipedia.org/wiki/LonWorkshttp://en.wikipedia.org/wiki/LonWorkshttp://en.wikipedia.org/wiki/LonWorkshttp://en.wikipedia.org/wiki/Actuatorhttp://en.wikipedia.org/wiki/Actuatorhttp://en.wikipedia.org/wiki/Actuatorhttp://science.howstuffworks.com/environmental/earth/geophysics/h2o.htmhttp://science.howstuffworks.com/environmental/earth/geophysics/h2o.htmhttp://science.howstuffworks.com/environmental/earth/geophysics/h2o.htmhttp://science.howstuffworks.com/environmental/earth/geophysics/h2o.htmhttp://en.wikipedia.org/wiki/Actuatorhttp://en.wikipedia.org/wiki/LonWorkshttp://en.wikipedia.org/wiki/BACnethttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/HVAC_control_systemhttp://en.wikipedia.org/wiki/Building_management_systemhttp://en.wikipedia.org/wiki/Building_automationhttp://en.wikipedia.org/wiki/Brushless_DC_electric_motorhttp://en.wikipedia.org/wiki/Airflowhttp://en.wikipedia.org/wiki/Variable_Frequency_Drivehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Mechanical_fan
  • 7/29/2019 what is air conditioner

    8/13

    Celsius). The chilled water is then piped throughout the building and connected to air handlers. This

    can be a versatile system where the water pipes work like the evaporator coils in a standard air

    conditioner. If it's well-insulated, there's no practical distance limitation to the length of a chilled-water

    pipe.

    Underfloor supply unit

    Underfloor air distribution (UFAD) is an air distribution strategy for providingventilationand space

    conditioning inbuildingsas part of the design of anHVACsystem. UFAD systems use the

    underfloorplenumbeneath araised floorto provide conditioned air through floordiffusersdirectly to

    the occupied zone.

    System description

    UFAD systems rely onair handling unitsto filter and condition air to the appropriate supply conditions

    so it can be delivered to the occupied zone. While overhead systems typically useductsto distribute

    the air, UFAD systems use the underfloor plenum formed by installation of araised floor. The plenum

    generally sits 0.3 and 0.46metres(12 and 18in) above the structural concrete slab, although lower

    heights are possible.[2][3]

    Specially designed floordiffusersare used as the supply outlets.[4]

    The most

    common UFAD configuration consists of a central air handling unit delivering air through a

    pressurized plenum and into the space through floor diffusers. Other approaches may incorporate fan

    poweredterminal unitsat the outlets, underfloor ducts, desktop vents or connections toPersonal

    Environmental Control Systems.[1]

    [edit]UFAD air distribution and stratification

    UFAD systems rely on the natural stratification that occurs when warm air rises due tothermal

    buoyancy. In a UFAD design, conditioned air stays in the lower, occupied part of the room, while heat

    sources such as occupants and equipment generatethermal plumes, which carry the warm air and

    heat source generated pollutants towards theceilingwhere they are exhausted through the return air

    ducts.[1]

    The temperature stratification created by the UFAD system has implication for space

    setpoints. Most of an occupant's body is in an area that is colder than the temperature at the

    thermostat height; therefore, current practice recommends raising thermostat setpoints compared to

    traditional overhead systems. The optimal ventilation strategy controls the supply outlets to limit themixing of supply air with room air to just below the breathing height of the space. Above this height,

    stratified and more polluted air is allowed to occur. The air that the occupant breathes will have a

    lower concentration of contaminants compared to conventional uniformly mixed systems.[1]

    Many factors, including the ceiling height,[5]

    diffuser characteristics, number of diffusers, supply air

    temperature, total flow rate, cooling load and conditioning mode[5]

    affect the ventilation efficiency of

    UFAD systems. Swirl diffusers and perforated-floor-panel diffusers have been shown to create a low

    air velocity in the occupied zone, while linear diffusers created the highest velocity in the occupied

    zone, disturbing thermal stratification and posing a potential draft risk.[5]

    Additionally, floor diffusers

    add an element of personal control within the reach of the occupant, as users can adjust the amount

    of air that is delivered by the diffuser though rotating the diffuser top.

    http://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/Buildinghttp://en.wikipedia.org/wiki/Buildinghttp://en.wikipedia.org/wiki/Buildinghttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Plenum_chamberhttp://en.wikipedia.org/wiki/Plenum_chamberhttp://en.wikipedia.org/wiki/Plenum_chamberhttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wiktionary.org/wiki/diffusehttp://en.wiktionary.org/wiki/diffusehttp://en.wiktionary.org/wiki/diffusehttp://en.wikipedia.org/wiki/Air_handlerhttp://en.wikipedia.org/wiki/Air_handlerhttp://en.wikipedia.org/wiki/Air_handlerhttp://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Metrehttp://en.wikipedia.org/wiki/Metrehttp://en.wikipedia.org/wiki/Metrehttp://en.wikipedia.org/wiki/Inchhttp://en.wikipedia.org/wiki/Inchhttp://en.wikipedia.org/wiki/Inchhttp://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Hanzawa-2http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Hanzawa-2http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Hanzawa-2http://en.wikipedia.org/wiki/Diffuser_(thermodynamics)#HVAChttp://en.wikipedia.org/wiki/Diffuser_(thermodynamics)#HVAChttp://en.wikipedia.org/wiki/Diffuser_(thermodynamics)#HVAChttp://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-BaumanOutlet-4http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-BaumanOutlet-4http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-BaumanOutlet-4http://en.wikipedia.org/wiki/Duct_(HVAC)#Terminal_unitshttp://en.wikipedia.org/wiki/Duct_(HVAC)#Terminal_unitshttp://en.wikipedia.org/wiki/Duct_(HVAC)#Terminal_unitshttp://en.wikipedia.org/w/index.php?title=Personal_Environmental_Control_Systems&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Personal_Environmental_Control_Systems&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Personal_Environmental_Control_Systems&action=edit&redlink=1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/w/index.php?title=Underfloor_air_distribution&action=edit&section=3http://en.wikipedia.org/w/index.php?title=Underfloor_air_distribution&action=edit&section=3http://en.wikipedia.org/w/index.php?title=Underfloor_air_distribution&action=edit&section=3http://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/wiki/Plume_(hydrodynamics)#Heathttp://en.wikipedia.org/wiki/Plume_(hydrodynamics)#Heathttp://en.wikipedia.org/wiki/Plume_(hydrodynamics)#Heathttp://en.wikipedia.org/wiki/Ceilinghttp://en.wikipedia.org/wiki/Ceilinghttp://en.wikipedia.org/wiki/Ceilinghttp://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Lee-5http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/wiki/Ceilinghttp://en.wikipedia.org/wiki/Plume_(hydrodynamics)#Heathttp://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/wiki/Stack_effecthttp://en.wikipedia.org/w/index.php?title=Underfloor_air_distribution&action=edit&section=3http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-design_guide-1http://en.wikipedia.org/w/index.php?title=Personal_Environmental_Control_Systems&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Personal_Environmental_Control_Systems&action=edit&redlink=1http://en.wikipedia.org/wiki/Duct_(HVAC)#Terminal_unitshttp://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-BaumanOutlet-4http://en.wikipedia.org/wiki/Diffuser_(thermodynamics)#HVAChttp://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Hanzawa-2http://en.wikipedia.org/wiki/Underfloor_air_distribution#cite_note-Hanzawa-2http://en.wikipedia.org/wiki/Inchhttp://en.wikipedia.org/wiki/Metrehttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Duct_(HVAC)http://en.wikipedia.org/wiki/Air_handlerhttp://en.wiktionary.org/wiki/diffusehttp://en.wikipedia.org/wiki/Raised_floorhttp://en.wikipedia.org/wiki/Plenum_chamberhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Buildinghttp://en.wikipedia.org/wiki/Ventilation_(architecture)
  • 7/29/2019 what is air conditioner

    9/13

    Direct Expansion Air Handling Unit (DX AHU)

    Central air conditioners fall into two categories: direct expansion (DX) or chilled water. Today, with the help of this

    articlefrom BrightHub.com, we will attempt to better describe one of these systems, direct expansion, which

    unlike chilled water systems that first chill water through a refrigeration plant then use that to chill the air, DX

    systems pass air directly over the cooling coil to be chilled.

    This means that the cooling efficiency of the DX system is much higher than water chilled units, but because it is

    not always feasible to carry the refrigerant piping over large distances, DX systems are usually only used for

    cooling small buildings or rooms on a single floor.

    http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2http://www.brighthub.com/engineering/mechanical/articles/50158.aspx?p=2
  • 7/29/2019 what is air conditioner

    10/13

    DX systems comprise of three main components:

    1. The Plant Room: This area of the DX system is comprised of the refrigeration system, compressor and

    condenser.

    2. The Air Handling Unit Room: The refrigerant leaving the condenser in the plant room enters the

    thermostatic expansion valve and then the air handling unit. This area is comprised of the evaporator or the

    cooling coil, air filter and the large blower.

    3. Air Conditioned Room: This is the room that is to be air conditioned. The ductwork running from the air

    handling unit filters the cooled air into these rooms.

    While the efficiency of DX systems is higher than water chilled systems, the refrigerant piping cannot be kept at

    very long distance since there will be lots of drop in pressure of the refrigerant along the way and there will also

    be cooling losses. So DX systems do not always make sense.

    Fan coil units

    Design and operation

    It should be first appreciated that 'Fan Coil Unit' is a generic term that is applied to a range of

    products. Also, the term 'Fan Coil Unit' will mean different things to users, specifiers and installers in

    different countries and regions, particularly in relation to product size and output capability.

    A fan coil unit may be concealed or exposed within the room or area that it serves.

    An exposed fan coil unit may be wall mounted, freestanding or ceiling mounted, and will typically

    include an appropriate enclosure to protect and conceal the fan coil unit itself, with return airgrilleand

    supply airdiffuserset into that enclosure to distribute the air.

    A concealed fan coil unit will typically be installed within an accessible ceiling void or services zone.The return air grille and supply air diffuser, typically set flush into the ceiling, will be ducted to and

    from the fan coil unit and thus allows a great degree of flexibility for locating the grilles to suit the

    ceiling layout and/or the partition layout within a space. It is quite common for the return air not to be

    ducted and to use the ceiling void as a return air plenum.

    The coil receives hot or cold water from a central plant, and removes heat from or adds heat to the air

    throughheat transfer. Traditionally fan coil units can contain their own internalthermostat, or can be

    wired to operate with a remote thermostat. However, and as is common in most modern buildings with

    aBuilding Energy Management System(BEMS), the control of the fan coil unit will be by a local

    digital controller or outstation (along with associated room temperature sensor and control valve

    actuators) linked to the BEMS via a communication network, and therefore adjustable and controllablefrom a central point, such as a supervisors head end computer.

    Fan coil units circulate hot or cold water through a coil in order to condition a space. The unit gets its

    hot or cold water from a central plant, ormechanical roomcontaining equipment for removing heat

    from the central building's closed-loop. The equipment used can consist of machines used to remove

    heat such as achilleror acooling towerand equipment for adding heat to the building's water such as

    aboileror a commercialwater heater.

    http://en.wikipedia.org/wiki/Grillehttp://en.wikipedia.org/wiki/Grillehttp://en.wikipedia.org/wiki/Diffuser_(thermodynamics)http://en.wikipedia.org/wiki/Diffuser_(thermodynamics)http://en.wikipedia.org/wiki/Diffuser_(thermodynamics)http://en.wikipedia.org/wiki/Heat_transferhttp://en.wikipedia.org/wiki/Heat_transferhttp://en.wikipedia.org/wiki/Heat_transferhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Building_Management_Systemhttp://en.wikipedia.org/wiki/Building_Management_Systemhttp://en.wikipedia.org/wiki/Building_Management_Systemhttp://en.wikipedia.org/wiki/Mechanical_roomhttp://en.wikipedia.org/wiki/Mechanical_roomhttp://en.wikipedia.org/wiki/Mechanical_roomhttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Water_heaterhttp://en.wikipedia.org/wiki/Water_heaterhttp://en.wikipedia.org/wiki/Water_heaterhttp://en.wikipedia.org/wiki/Water_heaterhttp://en.wikipedia.org/wiki/Boilerhttp://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Chillerhttp://en.wikipedia.org/wiki/Mechanical_roomhttp://en.wikipedia.org/wiki/Building_Management_Systemhttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Heat_transferhttp://en.wikipedia.org/wiki/Diffuser_(thermodynamics)http://en.wikipedia.org/wiki/Grille
  • 7/29/2019 what is air conditioner

    11/13

    Ventilation Controls

    Although a typical HVAC system has many controls, the control of outdoor air quantity that

    enters the building can have a significant impact on IAQ, yet typically is not part of standard

    practice. Demand controlled ventilation is addressed as a method ofhumidity control, but isnot otherwise discussed here because its primary use is to reduce the supply of outdoor air

    below the recommended minimum for the purposes of saving energy, not for improving

    IAQ.

    Supplying acceptable quantities of outdoor air to occupied spaces is a critical component of

    good indoor air quality. Yet nearly all school ventilation systems cannot indicate whether

    outdoor air is even being supplied to the school, much less gauge the quantity of that air.Virtually all existing school ventilation systems rely upon a fixed damper to regulate the

    amount of outdoor air. Yet wind, stack effect, unbalanced supply and return fans, and

    constantly changing variable air volume (VAV) systems can cause significant under- or over-

    ventilation, which can affect IAQ and energy costs. Combinations of these effects can even

    cause the intake system to actually exhaust air.

    These

    measuring stations are designed to work in limited duct space and with low air

    velocities. This is an easy task, as some manufacturers offer their airflow

    measuring stations in separate packages with dampers and actuators, and others

    are built into the AHU at the factory.

    Top of page

    Moisture and Humidity Control

    Uncontrolled moisture indoors can cause major damage to the building structure, as well as

    to furnishings and to finish materials like floors, walls, and ceilings. Uncontrolled moisture

    can triggermoldgrowth which not only damages the school facility, but can lead to health

    and performance problems for students and staff.

    Primary causes of indoor moisture problems in new schools include:

    Problem

    http://www.epa.gov/iaq/schooldesign/moisturecontrol.htmlhttp://www.epa.gov/iaq/schooldesign/moisturecontrol.htmlhttp://www.epa.gov/iaq/schooldesign/moisturecontrol.htmlhttp://www.epa.gov/iaq/schooldesign/hvac.html#contenthttp://www.epa.gov/iaq/schooldesign/hvac.html#contenthttp://www.epa.gov/mold/index.htmlhttp://www.epa.gov/mold/index.htmlhttp://www.epa.gov/mold/index.htmlhttp://www.epa.gov/mold/index.htmlhttp://www.epa.gov/iaq/schooldesign/hvac.html#contenthttp://www.epa.gov/iaq/schooldesign/moisturecontrol.html
  • 7/29/2019 what is air conditioner

    12/13

    If the air conditioning system is not running at all:

    1. Check the Room Thermostat Temperature Setting: Set the thermostat to at least 5degrees below room temperature. Our elderly mom has no patience with switches and

    controls. She regularly calls her air conditioning service company with a service

    request, sometimes late at night, because she has simply failed to set the temperatureon the thermostat lower than the room temperature. Don't drive your A/C like our

    mother.

    2. Check that the Room Thermostat is set to "Cool" not "Off" or "Heat". If thethermostat is not set to "cool" it is simply turning off your A/C.

    Check that electricity is on for the equipment. Check all switches and controls, including

    service switches, including outside by the compressor, inside at the air handler, and fuses or

    circuit breakers in the electrical panel.

    If At Least Some of the Air Conditioner or Heat Pump Equipment is Running

    but Cool Air is Not Being Delivered

    Step 1: Check the Outside Air Conditioning /Heat Pump Compressor-

    Condenser unit

    Is the outdoor compressor-fan unit (COMPRESSOR & CONDENSING COIL) running?

    If not, be sure that theoutdoor compressor/condenser unit service switchand the air

    conditioner indoor power switch, fuse, or circuit breaker are all in the "on" position.

    Check the outside compressor condensing coil for damage or blockage.

    A blocked condensing coil can cause the compressor to overheat, stop running, or become

    noisy and work poorly.A/C Compressor Problems

    Step 2: Check the Air Conditioning /Heat Pump Indoor Air Handler

    Is the indoor blower unit running? If not be sure that the electrical power switch at your

    furnace or air conditioner air-handler is in the "on" position. Typically the air handler or

    blower unit is indoors inside the basement, crawl area, or attic.

    Sometimes there is more than one switch, such as one right at the unit and another at the

    entry to the room where the equipment is located, or even upstairs on a higher floor if your

    air handler is in a basement or crawl space.

    Make sure that the blower compartment cover or door is properly closed or an interlockswitch may be keeping the system "off".

    http://www.inspectapedia.com/aircond/aircond15.htmhttp://www.inspectapedia.com/aircond/aircond15.htmhttp://www.inspectapedia.com/aircond/aircond15.htmhttp://www.inspectapedia.com/aircond/5Mc_Addition_2709_DJFC1s.jpghttp://www.inspectapedia.com/aircond/5Mc_Addition_2709_DJFC1s.jpghttp://www.inspectapedia.com/aircond/5Mc_Addition_2709_DJFC1s.jpghttp://www.inspectapedia.com/aircond/aircond15e.htm#ACComperssorhttp://www.inspectapedia.com/aircond/aircond15e.htm#ACComperssorhttp://www.inspectapedia.com/aircond/aircond15e.htm#ACComperssorhttp://www.inspectapedia.com/aircond/aircond15e.htm#ACComperssorhttp://www.inspectapedia.com/aircond/5Mc_Addition_2709_DJFC1s.jpghttp://www.inspectapedia.com/aircond/aircond15.htm
  • 7/29/2019 what is air conditioner

    13/13

    Also remember to check for a dirty, blockedCOOLING COIL or EVAPORATOR COIL. A coil

    blocked by ice or dirt will not produce cool air.A/C Cooling Coil Icing.

    Step 3: Check the Air Conditioning /Heat Pump Air Filter(s)

    If your air conditioning equipment is running but little or no cool air is coming out of the

    supply registers, check that your air filter(s) have not become blocked with dirt and debris.

    Step 4: Check the Air Conditioning /Heat Pump system duct work & air

    supply registers

    In ceilings, walls, or floors, where cool air is supposed to be delivered to various rooms in the

    building, be sure that the register is in the "open" position (you will be able to see through itinto the ductwork) and be sure you haven't blocked the supply registers with a carpet or

    furniture.

    Look for a duct damper or register that has been closed; look for a flex-duct section that has

    become disconnected, bent, or crimped or squashed. Remember that a duct may have become

    disconnected in an attic or crawl space.

    Look for an air filter that has come loose and blown into the ductwork, clogging it.

    Step 5: Check the Air Conditioning /Heat Pump indoor air handler blower

    fan assembly

    If the indoor air handler blower fan itself won't start, seeBLOWER FAN OPERATION &

    TESTING. Check for lost power, a fan motor that wont' start or has tripped a motor reset

    button or needs a start / run capacitor. Check for a blower fan that is loose on the motor drive

    shaft or for a broken or lost blower fan drive belt on pulley-driven blower systems.

    How to Diagnose Air Conditioner Output Cool Air Flow

    Too Weak, Too Cold, or Too Warm

    http://www.inspectapedia.com/aircond/Cooling_Coil.htmhttp://www.inspectapedia.com/aircond/Cooling_Coil.htmhttp://www.inspectapedia.com/aircond/Cooling_Coil.htmhttp://www.inspectapedia.com/aircond/aircond15e.htm#ACIcinghttp://www.inspectapedia.com/aircond/aircond15e.htm#ACIcinghttp://www.inspectapedia.com/aircond/aircond15e.htm#ACIcinghttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/Blower_Fan.htmhttp://www.inspectapedia.com/aircond/aircond15e.htm#ACIcinghttp://www.inspectapedia.com/aircond/Cooling_Coil.htm