Window and Package Air Conditioning Units

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Questions and Answers

What is the primary advantage of window type air conditioning units?

  • They are cost-effective for large installations.
  • They occupy less space and have lower maintenance costs. (correct)
  • They require extensive ductwork.
  • They can be easily repaired in the field.

What is a significant disadvantage of window type air conditioning units?

  • Repairs must be conducted in a workshop after cutting the sealed housing. (correct)
  • They require frequent cleaning of the cooling coil.
  • They can leak refrigerant easily.
  • They are less efficient than central air conditioning systems.

What type of compressor motor is commonly found in modern window air conditioning units?

  • Belt-driven compressor motors.
  • Open type motor-compressor units.
  • Variable speed inverter motors.
  • Sealed type motor-compressor units. (correct)

How is the refrigerant controlled in window type air conditioning units?

<p>Through a capillary system. (D)</p> Signup and view all the answers

Which of the following maintenance tasks is important for window air conditioning units?

<p>Cleaning the condenser coil and cooling coil regularly. (A)</p> Signup and view all the answers

What is the typical power supply requirement for window type air conditioning units?

<p>230 V up to 3 HP. (D)</p> Signup and view all the answers

Which factor significantly increases the installation cost of window air conditioning units?

<p>The inclusion of multiple units for a large area. (D)</p> Signup and view all the answers

Which method can be used for cleaning the condenser coils of window type units?

<p>Brushing or using compressed air. (B)</p> Signup and view all the answers

What should be checked if external mounting is used for a compressor?

<p>Mounting springs (C)</p> Signup and view all the answers

What size range do package units typically cover?

<p>4 to 12 tons (D)</p> Signup and view all the answers

What is a key disadvantage of package units compared to central plants?

<p>Higher installation cost (B)</p> Signup and view all the answers

Where is the air conditioning plant typically located in a central plant system?

<p>In the basement (C)</p> Signup and view all the answers

What function does the control panel on a package unit serve?

<p>It controls cooling and fan operation (C)</p> Signup and view all the answers

What is necessary to control the amount of air admitted at each outlet in a central plant system?

<p>Damper vanes (A)</p> Signup and view all the answers

What typical problem is posed by the duct system in large buildings?

<p>Difficulty in structural accommodation (A)</p> Signup and view all the answers

What maintenance task is suggested for dampers within the system?

<p>Oil if necessary (D)</p> Signup and view all the answers

What is a common element of both package units and central plants?

<p>Contain elements for ventilation and cooling (A)</p> Signup and view all the answers

What is the recommended slope for the unit towards the outside?

<p>1/2 to 3/4 inches (C)</p> Signup and view all the answers

What is a significant limitation of a central plant air conditioning system?

<p>It allows air mixing from different areas. (B)</p> Signup and view all the answers

How does a desert cooler maintain comfortable room conditions?

<p>By evaporating water to cool and humidify incoming air. (B)</p> Signup and view all the answers

What design feature is necessary for a central air conditioning system to ensure reliability?

<p>Having at least two complete independent units (B)</p> Signup and view all the answers

What is a crucial factor to maintain temperature variation within a central air conditioning system?

<p>Continuous adjustment and experimentation (D)</p> Signup and view all the answers

What is a drawback associated with the ducting in a central air conditioning system?

<p>It occupies considerable space. (A)</p> Signup and view all the answers

What happens to the air as it passes through the wetted pad in a desert cooler?

<p>It cools and humidifies. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the central plant air conditioning system?

<p>Capability for independent room temperature control (D)</p> Signup and view all the answers

What is the primary mechanism of cooling in a desert cooler?

<p>Evaporative cooling (D)</p> Signup and view all the answers

Why is a central air conditioning system considered unsuitable for small rooms?

<p>Air temperature adjustment is challenging. (C)</p> Signup and view all the answers

What type of environments are best suited for the use of desert coolers?

<p>Dry and arid climates (A)</p> Signup and view all the answers

What is a major disadvantage of hermetically sealed compressors used in water coolers?

<p>Cooling will stop in case of electric supply failure. (D)</p> Signup and view all the answers

What material are the storage tanks for water coolers typically made of?

<p>Stainless Steel, G.I., or Brass (A)</p> Signup and view all the answers

How is the refrigerant controlled in open-type water cooler units?

<p>By an expansion valve (C)</p> Signup and view all the answers

What maintenance activity is recommended for ensuring safety in refrigerators and water coolers?

<p>Inspect insulation resistance of wiring every six months. (D)</p> Signup and view all the answers

In storage-cum-instantaneous water coolers, what happens to the refrigerant after it passes through the chiller coils?

<p>It is passed through the outer tube of the evaporator coils. (A)</p> Signup and view all the answers

What type of refrigerant is commonly used in domestic refrigerators?

<p>Freon22 (A)</p> Signup and view all the answers

What is the primary function of the compressor in a refrigerator?

<p>To compress refrigerant and circulate it (B)</p> Signup and view all the answers

How is the condenser in domestic refrigerators designed?

<p>By laying the condenser tube over a metal sheet (C)</p> Signup and view all the answers

What is the primary purpose of the evaporator unit in a refrigerator?

<p>To absorb heat and cool the air (C)</p> Signup and view all the answers

What distinguishes instantaneous water coolers from other types?

<p>They cool water as it flows without storage (B)</p> Signup and view all the answers

What type of motor is typically used in domestic refrigerator compressors?

<p>High torque squirrel cage induction motor (B)</p> Signup and view all the answers

Which mechanism controls the operation of the compressor in a refrigerator?

<p>An adjustable thermostat (C)</p> Signup and view all the answers

What is the temperature range preferred for drinking water from water coolers?

<p>10°C to 13°C (A)</p> Signup and view all the answers

What feature distinguishes the capillary system from traditional expansion valves in refrigerators?

<p>Simplification of the cooling process (B)</p> Signup and view all the answers

What design is used in instantaneous water coolers for maximizing efficiency?

<p>Tube-in-tube arrangement (B)</p> Signup and view all the answers

What is a significant disadvantage of storage type water coolers?

<p>Possible deposition of mineral salts on the evaporator coils (A)</p> Signup and view all the answers

In storage-cum-instantaneous type water coolers, what role does the chiller play?

<p>It cools water before it enters the storage tank (C)</p> Signup and view all the answers

What is the purpose of checking insulation resistance and bonding to earth in refrigeration equipment?

<p>To ensure safety during operation (A)</p> Signup and view all the answers

Which component is typically used to control refrigerant flow in sealed units?

<p>Capillary tube (A)</p> Signup and view all the answers

What maintenance practice is suggested for ensuring optimum performance of water coolers?

<p>Regular cleaning of evaporator coils to prevent mineral build-up (C)</p> Signup and view all the answers

Which factor makes maintenance of window type air conditioning units less demanding compared to other systems?

<p>The sealed nature of the system (C)</p> Signup and view all the answers

What can be used to check the cleanliness of the cooling coils in window type air conditioning units?

<p>Compressed air or a brush (B)</p> Signup and view all the answers

What appears to be a consequence of the sealed design in window type air conditioning units?

<p>Field repairs are challenging (C)</p> Signup and view all the answers

During periodic maintenance of window type air conditioning units, which aspect is specifically recommended to be monitored?

<p>Condenser and cooling coils (B)</p> Signup and view all the answers

Why might the initial installation cost of window type units be significantly higher for large areas?

<p>Installation of numerous individual units (A)</p> Signup and view all the answers

What is the primary material used in the construction of the sealed motor-compressor units in modern window air conditioners?

<p>Brazed joints for sealing (A)</p> Signup and view all the answers

What advantage do window type air conditioners offer regarding the use of additional infrastructure?

<p>They eliminate the need for ductwork. (D)</p> Signup and view all the answers

What impacts the healthiness of both the atmosphere and the air conditioning unit itself?

<p>The importance of periodic maintenance (D)</p> Signup and view all the answers

What is a significant disadvantage of using a package unit compared to a central plant system?

<p>Limited to smaller spaces (D)</p> Signup and view all the answers

What is the primary function of the damper vanes in a central plant system?

<p>Adjust the airflow at each outlet (C)</p> Signup and view all the answers

Which component is crucial for ensuring that cooled air is distributed uniformly in a central air conditioning system?

<p>Ducting system (D)</p> Signup and view all the answers

What maintenance task is associated with the compressor in external mountings of air conditioning units?

<p>Inspecting and replacing mounting springs (D)</p> Signup and view all the answers

What primary disadvantage can arise from the use of bulky ducting in central air conditioning systems?

<p>Structural installation challenges (D)</p> Signup and view all the answers

What is one of the main reasons for higher installation costs associated with package units?

<p>Complex system designs (D)</p> Signup and view all the answers

Which aspect of the control panel is not typically found in a package air conditioning unit?

<p>Detailed error reporting (A)</p> Signup and view all the answers

What is typically required in larger sizes of package units to ensure efficient operation?

<p>Water cooling systems (B)</p> Signup and view all the answers

What is the primary type of compressor used in most domestic refrigerators?

<p>Hermetic reciprocating compressor (C)</p> Signup and view all the answers

Which refrigerant is predominantly used in domestic refrigerators?

<p>Freon22 (B)</p> Signup and view all the answers

What common issue can arise if compressor mounting springs lose their tension over time?

<p>Heightened operational noise (A)</p> Signup and view all the answers

What type of air conditioning plant design is most suitable for large, unpartitioned spaces?

<p>Central plants (A)</p> Signup and view all the answers

What is the function of the capillary in a refrigerating system?

<p>To regulate the flow of refrigerant (C)</p> Signup and view all the answers

In an instantaneous water cooler, what system is used to maximize efficiency?

<p>Tube-in-tube arrangement (A)</p> Signup and view all the answers

How does the evaporator unit in a refrigerator help maintain temperature?

<p>By circulating cold air from the freezer (D)</p> Signup and view all the answers

What principle does the motor in a domestic refrigerator's compressor typically employ?

<p>Capacitor start principle (B)</p> Signup and view all the answers

What is the main physical arrangement of the condenser in basic refrigerator designs?

<p>Flat plates on a heat sink (C)</p> Signup and view all the answers

What differentiates an instantaneous water cooler from a storage type water cooler?

<p>It cools water as it flows through (B)</p> Signup and view all the answers

Which mechanism automatically controls the compressor operation in refrigerators?

<p>Adjustable thermostat (A)</p> Signup and view all the answers

What is the preferred temperature range for drinking water produced by water coolers?

<p>10OC to 13OC (A)</p> Signup and view all the answers

What is a key drawback of the central plant air conditioning system related to air quality?

<p>It can lead to the mixing of different air pollutants. (A)</p> Signup and view all the answers

Which of the following describes the primary operation principle of a desert cooler?

<p>Evaporative cooling using wetted pads. (C)</p> Signup and view all the answers

What inherent disadvantage does a central air conditioning system present for buildings with many small rooms?

<p>Difficulty in adjusting individual room temperatures. (C)</p> Signup and view all the answers

Which characteristic is NOT associated with the compressor plant in a central air conditioning system?

<p>It requires regular user intervention. (C)</p> Signup and view all the answers

What is a significant requirement for ensuring effective temperature variation in a central air conditioning system?

<p>Consistent adjustment and experimentation. (A)</p> Signup and view all the answers

How does the desert cooler affect the air when it is circulated into the room?

<p>It picks up latent heat and maintains comfort. (B)</p> Signup and view all the answers

What is a structural issue related to the central plant system's ducting?

<p>It can occupy significant physical space. (D)</p> Signup and view all the answers

Which mechanism does a desert cooler use to introduce fresh air into the room?

<p>Constant ventilation through an opening. (C)</p> Signup and view all the answers

In a central air conditioning system, what is the purpose of having a standby unit?

<p>To allow for maintenance on the working unit. (D)</p> Signup and view all the answers

What aspect of air management creates a challenge in a central plant system for various room types?

<p>Customization of air temperature in different sections. (B)</p> Signup and view all the answers

Flashcards

Window AC unit

A self-contained air conditioner with the compressor, condenser, evaporator, and refrigerant piping in one compact assembly.

Capacity (of a window AC unit)

The amount of air that the unit can cool in a given time, usually measured in tons.

Sealed system (in AC unit)

A system in which the refrigerant piping is sealed to prevent refrigerant gas leakage.

Maintenance of AC unit

Regular checks and cleaning of the condenser and cooling coils to ensure proper unit efficiency

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Condenser coil

Part of the AC unit that releases heat from the refrigerant.

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Cooling coil

Absorbs heat from the space to be cooled.

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Periodic Maintenance

Regular maintenance schedule recommended for optimal unit performance and to ensure equipment life

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Cleaning Condenser and Cooling coil

Removing dust and debris from the coils to improve cooling efficiency and prevent damage.

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Air Duct Cleaning

Maintaining fresh air ducts by cleaning and checking for proper functionality.

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Compressor Mounting Springs

Springs that hold the compressor in place; their tension decreases over time.

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Earthing Connections

Checking electrical grounding points; vital for safety.

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Package Unit

A large air-conditioning unit, often floor-mounted, suitable for space cooling.

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Package Unit Capacity

The cooling power of a package unit measured in tons (4, 6, 8, 12).

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Central Plant

Centralized air-conditioning system for large spaces; multiple compressors with associated equipment.

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Central Plant Ducting

A complex network of ducts for distributing conditioned air to all parts of the building.

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Damper Vanes

Adjustable vanes within ducts for controlling airflow.

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Unit Slope

The inclination of the AC unit, which should be 1/2 to 3/4 inch towards the outside.

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Air Fillers

Checking and maintaining the fresh air intake components of the unit.

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Centralized AC System

An air conditioning system where a central unit cools and distributes air throughout a building using a network of ducts.

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Standby Unit

A backup unit in a centralized AC system that is ready to take over if the main unit fails.

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Evaporative Cooling

A cooling method that uses water evaporation to lower air temperature.

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Desert Cooler

A device that uses evaporative cooling to cool air, often used in hot, dry climates.

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Wetted Pad

A material in a desert cooler that is continuously wetted to promote evaporation.

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Sensible Heat

The heat that can be felt and measured by a thermometer.

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Disadvantages of Central AC

Central AC systems can be inflexible, create mixing of air, and require large ductwork.

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Why Central AC is Bad for Small Rooms?

Central AC systems don't allow individual room temperature adjustments, making them unsuitable for small spaces.

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Mixing of Air

Central AC can lead to mixing of air from different areas, including smoke, bacteria, and odors.

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Large Ducting

Central AC requires extensive ductwork to distribute cooled air.

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What are the two main types of water coolers?

Water coolers are typically categorized as 'direct contact' and 'storage' types. Direct contact coolers use refrigerant to cool the water directly, while storage coolers have a separate tank where the water is stored and cooled.

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What's the main difference between sealed and open type compressors?

Sealed compressors are completely enclosed units, preventing refrigerant leaks and requiring minimal maintenance. Open type compressors have a more exposed design and typically require more frequent maintenance.

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How do evaporator coils affect water cooling?

Evaporator coils are crucial for heat exchange. They absorb heat from the water in the storage tank or directly from the water flow, allowing the refrigerant to cool the water.

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Why is maintenance crucial for water coolers?

Regular maintenance like cleaning evaporator coils and checking electrical insulation ensures efficient and safe operation, preventing mineral build-up, refrigerant leaks, and electrical hazards.

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What is the 'leave it alone' rule?

This rule encourages minimal intervention with sealed systems like refrigerators and water coolers. Tinkering can lead to damage and safety risks. Only qualified technicians should service these systems.

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Refrigerator Working Principle

Domestic refrigerators usually operate on the vapor compression system, using a hermetically sealed compressor unit and a refrigerant like Freon22. The system includes an evaporator, condenser, and expansion valve.

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Refrigerator Compressor Types

The compressor in a refrigerator can be either rotary pump type or reciprocating type. Both are electric and used to circulate the refrigerant.

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Refrigerator Expansion Valve

Instead of a traditional expansion valve, refrigerators use capillary tubes to control the refrigerant flow. This simplifies the system.

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Refrigerator Condenser Design

The condenser in a refrigerator is simplified by using a single metal sheet with tubes running back and forth, acting as a heat sink. No cooling fan is needed.

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Refrigerator Cooling System

The freezer compartment cools the entire refrigerator by setting up convection currents of air. The rest of the cabinet cools indirectly.

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Refrigerator Thermostat Control

An adjustable thermostat controls the compressor, turning it on and off based on the desired temperature. A relay connects the thermostat to the compressor.

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Water Cooler Function

A water cooler uses refrigeration to cool drinking water, typically to between 10°C and 13°C.

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Water Cooler Types

Water coolers can be classified into two main types: instantaneous and storage. Instantaneous coolers cool water on demand, while storage coolers have a tank for holding chilled water.

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Instantaneous Water Cooler Design

Instantaneous coolers have no storage tank and cool water immediately. The evaporator and refrigerant coils are close together for efficiency.

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Water Cooler Efficiency

Instantaneous coolers use a tube-in-tube arrangement for the evaporator and refrigerant coils, maximizing efficiency. The evaporator is also insulated to minimize heat transfer.

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Sealed system (AC)

A system where refrigerant piping is sealed to prevent leaks, requiring minimal maintenance.

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Advantages of window AC units

Low maintenance cost, no ductwork required, compact size, no shaft seal or alignment issues, better compressor cooling.

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Disadvantages of window AC units

Difficult to repair, expensive for large areas, can't be customized for individual rooms.

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Periodic maintenance for AC units

Regular cleaning of condenser and cooling coils is essential for healthy operation and efficiency.

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Cleaning the condenser coil

Remove dust and debris to improve cooling efficiency.

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Cleaning the cooling coil

Remove dust and debris to improve cooling efficiency.

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Checking cleanliness of coils

Use a naked light to check for dust and debris in between the fins of the condenser and cooling coils.

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Oil the Dampers

Regularly lubricating the dampers in the duct system for smooth operation and reduced noise.

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Sealed vs. Open Compressors

Sealed compressors are closed units that prevent refrigerant leaks and require minimal maintenance. Open compressors have a more exposed design and require more frequent servicing.

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Evaporator Coils & Water Cooling

Evaporator coils absorb heat from the water in the storage tank or directly from the water flow, allowing the refrigerant to cool the water.

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Water Cooler Maintenance

Regular maintenance like cleaning evaporator coils and checking electrical insulation is crucial for efficient and safe operation.

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'Leave it Alone' Rule

Minimal intervention is best for sealed systems like refrigerators and water coolers to avoid damage and safety risks. Only qualified technicians should service these systems.

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Refrigerator Components

Key components include the compressor, condenser, evaporator, and expansion valve. The compressor circulates the refrigerant, the condenser releases heat, the evaporator absorbs heat, and the expansion valve controls refrigerant flow.

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Study Notes

Window Type Units

  • Window units are self-contained, compact assemblies with compressors, condensers, evaporators, refrigerant piping, and filters.
  • Common capacity range is 1/2 to 2 tons, with motors up to 3 HP and 230V.
  • Modern units use sealed motor-compressor units with brazed joints for improved gas leakage prevention.
  • Capillary systems control refrigerant, eliminating expansion valve and liquid receiver components.
  • Maintenance is low due to sealed systems.
  • Units require minimal space; useful for smaller, separated rooms.
  • Disadvantage: Cannot be repaired in the field; requiring workshop repair after housing removal. Higher initial cost compared to central units for larger areas.
  • Periodic maintenance is crucial for optimal functioning and health.
    • Condenser coil, cooling coils, and fans need attention (dusting with compressed air or brush).

Package Units

  • Functionally similar to window units but larger, floor-mounted.
  • Available in various capacities (4, 6, 8, and 12 tons).
  • Contain all cooling, dehumidifying, ventilating, and circulating air elements.
  • Often employ water-cooled condensers.
  • Compressor types can be hermetically sealed, semi-sealed, or open.
  • Control panel has settings(OFF, Fan, Cool), and a temperature control knob.
  • High initial installation cost for large areas.

Central Plants

  • Best for large buildings, theaters, and open-plan offices.
  • Multiple heavy compressor units, condensers & evaporators are located centrally.
  • Ductwork delivers conditioned air throughout the building.
  • Return air ducts are required to send air back to the central plant for recirculation.
  • Ductwork is expansive and can cause structural issues.
  • Temperature variance within the building should ideally remain within 1 or 2 degrees Celsius for proper operation

Schematic Diagram of AC System

  • Diagram shows the flow of refrigerant and air through components.
  • Indicates operating pressures and temperatures at key points in the system.

Air Conditioning System (Central Plant)

  • System may have inherent disadvantages other than large ducts, including issues with individual room temperature controls, air mixing in building areas, and occupying considerable space.

Desert Coolers

  • Work based on evaporative cooling, using a fan that draws in outside air, which is then passed through a wetted pad, cooling and humidifying the air before circulating it into the room.

Water Coolers/Refrigerators

  • Refrigerators primarily use vapor compression systems with either reciprocating or rotary pumps.
  • Often use Freon-22 refrigerant.
  • Motors typically use squirrel cage induction designs.
  • Water coolers can be classified as instantaneous or storage-type models.
  • Storage units store water in tanks with coils for cooling.
  • Instantaneous units have no storage, cooling water in real-time via coils.

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