Types of Air Conditioners
Classification based on major function
(a) Comfort A.C.: Creating atmospheric conditions conductive to human health, comfort & efficiency. A.C. in home, offices, stores, restaurants, theatres, hospitals etc. are of these types.
(b) Industrial A.C.: The purpose of these system is to control atmospheric conditions primarily for proper conduct of research & manufacturing e.g. electronics & computer industries, paper mills, textile mills, candy factories, photo processing etc.
Classification based on equipments ranged
a) Unitary or "packed" A.C
b) Spit A.C.
c) Central A.C.
d) Combination of above.
Classification based on season of use year:
a) Winter A.C. system: These systems, when properly designed & installed maintain indoor atmospheric conditions for winter comfortable, namely temperature, humidity. Air purity & air movements, when outside temperature is very cold.
b) Summus A.C.: Maintains indoor condition comfortable when outside atmospheric conditions are not comfortable, but it is very hot & dry.
c) All year round A.C.: Maintains indoor temperature comfortable throughout the year, while outside temperature may be very cold or hot
Classification based on installation position
Windows AC
Split or Ductless AC
Centralised AC
MAIN TYPE OF AIR-CONDITIONERS
1) Window AIR-CONDITIONERS
2) Split air-conditioners
3) Centralised air-conditioners
4) Package air-conditioners
1.Window AIR-CONDITIONERS
Window air conditioners are one of the most commonly used and cheapest type of air conditioners.
To install one of these units, you need the space to make a slot in the wall, and there should also be some open space behind the wall.
Window air-conditioner units are reliable and simple-to-install solution to keep a room cool while avoiding the costly construction of a central air system.
Better yet, when the summer heat dies down, these units can be easily removed for storage, and you can use the window sill for other purpose
Part of Window AC
Front Panel:
The front panel is the one that is seen by the user from inside the room where it is installed
The front panel has adjustable horizontal and vertical(some models) louvers where the direction of air flow are adjustable to suit the comfort of the users
The fresh intake of air called VENT (ventilation) is provided at the panel in the event that user would like to have a certain amount of fresh air from the outside.
Indoor Side Components:
Cooling Coil
Fan Blower
Operation Panel
Filter Drier
Outdoor Side Components:
Compressor
Condenser Coil
Propeller Fan
Fan Motor
Drain Pan
Construction
It contains:
WORKING OF WINDOW AIR CONDITIONER
The coils and pipes in an air conditioning unit contain refrigerant gas. The refrigerant gas enters the compressor as warm, low-pressure gas and leaves it as hot, high-pressure gas.
In the condenser coils, hot, compressed refrigerant gas loses heat to the outdoor air and becomes liquid while it is still warm.
The warm, liquid refrigerant passes through the tiny opening of the expansion valve, expands, and partly turns to gas at a low temperature.
In the cooling coils, the refrigerant takes up heat from the indoor air and leaves the coils as warm, low-pressure gas.
The indoor air gives up heat to the refrigerant in the cooling coils and also loses moisture as it is chilled. The moisture condenses on the coils and trickles down to outside drain holes. Cooled air is blown back into the room.
Advantages of the Window Air Conditioner
Increased comfort level.
In extreme heat, air-conditioning can be a life saver.
Most air conditioners also reduce the humidity level, which helps both comfort, and reduces mold growth.
Less noise as the windows will be closed.
Prevents the dust entering the room as the windows will be closed.
Gives constant temperature.
Attractive design.
Simple control.
Easy maintenance.
Easy installation.
Disadvantages of the Window Air Conditioner
Most air conditioners use a substantial amount of energy.
High cost money
Contributing to pollution from power plants.
Older models contain chemicals that can damage the environment if they escape.
Encourages laziness,
Habitant spending time indoors instead of out
Habitants have less contact with nature.
Too cool temperatures will lead to improper blood circulation
Effects the environment by releasing the CFC's.
Split Air-Conditioning System
The split air conditioner comprises of two parts: the outdoor unit and the indoor unit.
The outdoor unit, fitted outside the room, houses components like the compressor, condenser and expansion valve.
The indoor unit comprises the evaporator or cooling coil and the cooling fan. For this unit you don't have to make any slot in the wall of the room.
Further, the present day split units have aesthetic looks and add to the beauty of the room. The split air conditioner can be used to cool one or two rooms
Construction
There are two main parts of the split air conditioner. These are:
1) Outdoor unit:
This unit houses important components of the air conditioner like the compressor condenser coil and also the expansion coil or capillary tubing.
This unit is installed outside the room or office space which is to be cooled.
The compressor is the maximum noise making part of the air conditioner, and since in the split air conditioner, it is located outside the room, the major source of noise is eliminated.
In the outdoor unit there is a fan that blows air over the condenser thus cooling the compressed Freon gas in it.
This gas passes through the expansion coil and gets converted into low pressure, low temperature partial gas and partial liquid Freon fluid.
2) Indoor unit:
It is the indoor unit that produces the cooling effect inside the room or the office
This is a beautiful looking tall unit usually white in color, though these days a number of stylish models of the indoor unit are being launched.
The indoor unit houses the evaporator coil or the cooling coil, a long blower and the filter.
After passing from the expansion coil, the chilled Freon fluid enters the cooling coil.
The blower sucks the hot, humid and filtered air from the room and it blows it over the cooling coil.
As the air passes over cooling coll its temperature reduces drastically and also loses the excess moisture.
The cool and dry air enters the room and maintains comfortable conditions of around 25-27 degree Celsius as per the requirements.
Major Parts of split air conditioning systems
Working of A Split Air Conditioner
In brief below is the process of how the split-type AC works in general. It involves a lot more technical aspects than what we listed here but we try to keep it simple for everyone to understand the concept.
The evaporator coil will absorb heat in the room and release it to the refrigerant
The refrigerant will move into the compressor
The compressor will compress the refrigerant even further until it forms a liquid
The liquid will be sent to the condenser coil where it will exchange heat with the environment and form a gas again with the motor fan to dissipate the heat
The hot liquid refrigerant will travel to the expansion valve. Depressure the refrigerant and cool it down
Low-pressure cold liquid will be flowing into the evaporator coil and will distribute out through the help of the air blower
The process will repeat and circulate until you turn them off
TYPES OF SPLIT AC
Wall mounted:
Wall mounted split ACs are the most popular.
The indoor unit is placed in the room and duct cannot be concealed.
It is generally for small rooms which can be cooled uniformly easily.
Like split ACs, a tower AC set consists of 2 units- one internal and an external.
It rather occupies some space on the floor.
Tower air conditioners usually have high cooling capacity and suitable for very large rooms.
These are useful in rooms where you connot mount the AC in your wall.
These are generally more expensive than wall mounted ACs and hence less popular for homes.
Advantages
Floor mounted/Tower AC/vertical AC:
Vertical Air Conditioning System is a form of central air conditioning system consisting mainly vertical vents that direct cool air from the floor itself.
It is used where floor requires cool air but there is a lack of walls and/or ceiling is too high.
These vents are omnidirectional because they can be turned in any direction.
Ceiling mounted/Cassette AC:
These space-saving ACs are shaped like cassettes and are designed to be installed an onl
The panel of these air conditioners is designed to oll kinds of home déco
They are stylish, and are known to Eat performances.
Most cassette type air conditioners
They are perfect for large spaces where windows or split AC may not reach out.
They look oosthetically be as the unit is concealed, however this ends g
The price for this type of AC is higher than wall mounted or floor mounted split ACs.
Advantages
Multi Split ACS
Multi-splits are multiple split ACs connected to one outdoor unit.
The indoor units can be used individually or at the same time as needed if this is supported. If both the units are used then the capacity of the ACs will be divided. The fan and condenser of the outdoor unit will be controlled based on the signals from indoor units.
This primary saves cost as instead of 2 split ACs you can use this type of AC.
Advantage of Multi Split ACS
Advantages of multi-split ACE
Saves installation space
Can be used individually or simultaneously
Independent control
Compact Design
Good EER
Saves on running costs
Convenient and economical
Disavantages of multi-split AC
Expensive compared to a single unit split AC
Limited range of capacities and models
More prone to leakage as number of Indoor units increases
Advantages of the split air conditioner
Internal unit takes up less space for installation
Usually more silent than window ACs
Minimally affect your home decor
Can be installed in room with no windows
The split type of air conditioner is efficient in terms of cooling room.
It has a great power consumption with low energy cost.
It has fewer parts that can be easily maintained and fewer things that can go wrong, so the maintenance costs are low too with such an AC system if it is properly maintained.
The noise is also low because the amount of air moved by the fan is small, so it will not create any noise. Plus the compressor and motor fan are located outside.
If the aircond is periodically service and properly maintained, it has a longer life span for you to use efficiently and with less fuss.
The aircond installation process is quick and easy since it does not require ducting as with a central air conditioning system.
Disadvantages of the split air conditioner
The highest horsepower of the split type can go up to 3 horsepower only. Use our AC horsepower calculator to determine the capacity required for your room.
If you have a very large area that needs to be cooled down, you might need more than one unit.
It can significantly affect the look of your house since most of them have a large box hanging outside your house with an external condenser unit and with an external indoor unit in your living room or bedroom that you can see and not hidden.
Centralised Air-Conditioning System
The central air conditioning plants or the systems are used when large buildings, hotels, theaters, airports, shopping malls etc. are to be air conditioned completely.
The window and split air conditioners are used for single rooms or small office spaces.
If the whole building is to be cooled it is not economically viable to put window or split air conditioner in each and every room.
Further, these small units cannot satisfactorily cool the large halls, auditoriums, receptions areas etc.
Construction: The construction of the equipment is shown in the figure.
Components of Central AC
Air handling unit(AHU)
Supplying duct
Return duct
Diffusers/Registers
Compressor
Condenser
Expansion device
Evaporator
Thermostat
Central AC's main Components
The condenser-is the unit that sits outside your home and contains the compressor, condensing coil, fan and motor and all the system's electrical components.
The evaporator-also known as the A coil - because of it's A shape, is installed inside your furnace's duct system. This coil must be properly matched to the outside unit and should always be replaced when you purchase a new cooling system in order to maintain maximum system efficiency and prolong the life of your new air conditioner.
The line set -The line set is the copper tubing that connects the evaporator to the condenser. The black insulation or armaflex on this tubing keeps it from sweating as the cold refrigerant passes through it. The line set can normally be reused as long as it is properly sized, has no leaks and we are using the same type of refrigerant. We will cover the two types of refrigerants in just a moment.
The blower - The blower is provided by your heating system, in other words, your furnace. This is arguably the most important part of your cooling system. Everything your new cooling system is capable of doing is dependant upon proper airflow through the A coil. If your blower is old or dirty it may move too little air and the cooling system will freeze up. Poor airflow will cause your lower level to get very cold and your upper floors to get very warm. This is a very common problem and one reason many customers consider replacing older furnaces when they replace their cooling system- the heat works fine but the airflow is marginal. However, if your furnace blower is in good shape replacing your heating system is not necessary.
WORKING OF CENTRAL AC
Central air conditioners circulates cool air through a system of supply and return ducts.
Supply ducts and registers (i.e., openings in the walls, floors, or ceilings covered by grills) carry cooled air from the air conditioner to the home.
This cooled air becomes warmer as it circulates through the home, then it flows back to the central air conditioner through return ducts and registers.
TYPES OF CENTRAL AC
A central air conditioner is either a split-system unit or a packaged unit.
Split-system: An outdoor metal cabinet contains the condenser and compressor, and an indoor cabinet contains the evaporator
Packaged Unit: The evaporator, condenser, and compressor are all located in one cabinet, which usually is placed on a roof or on the ground
ADVANTAGES
Improves indoor air quality.
Level of indoor noise is almost negligible.
Maintains a constant temperature and humidity throughout the conditioned space.
DISADVANTAGES
Packaged Air-Conditioning System
These systems include window mounted or wall bracket conditioners.
Most of these units are air cooled, though water-cooled types have also been made.
The window and split air conditioners are usually used for the small air conditioning capacities up to 5 tons.
The central air conditioning systems are used for where the cooling loads extend beyond 20 tons.
The packaged air conditioners are used for the cooling capacities in between these two extremes.
The packaged air conditioners are available in the fixed rated capacities of 3,5,7,10 and 15 tons.
These units are used commonly in places like restaurants, telephone exchanges, homes, small halls, etc.
Construction: The construction of the equipment is shown in the Figure.
Components
This self contained unit is assembled in a casing where all the air conditioning components are housed. They include:
Compressor
Water cooled or air cooled condenser
Electric panel
Thermosatic expansion valve
Air filter
Front panel
Evaporator fan and housing
Heating and humidifying components
Working:
Room air enters the casing at the front panel. It is mixed with part of the outdoor air.
This mixture is forced over the cooling coils by a centrifugal fan, which is driven electrically.
Some of the moisture in the air is condensed and disposed off by means of a single ring of the propeller type of condenser.
The units are hermetically sealed.
Reciprocating compressors using nontoxic refrigerant and driven by capacitor motors are used.
Types of Packaged Air-Conditioning System
Two types of condensers are used in packaged systems
Air-cooled - These condensers are cooled by the surrounding air. These are more common for residential use.
Water-cooled - These condensers require a cooling tower, so they're used primarily for large commercial applications where water is plentiful.
Packaged Air Conditioners with Air Cooled Condensers
In this packaged air conditioners the condenser of the refrigeration system is cooled by the atmospheric air.
There is an outdoor unit that comprises of the important components like the compressor, condenser and in some cases the expansion valve (refer the figure below).
The outdoor unit can be kept on the terrace or any other open place where the free flow of the atmospheric air is available.
The fan located inside this unit sucks the outside air and blows it over the condenser coil cooling it in the process.
The condenser coil is made up of several turns of the copper tubing and it is finned externally.
The packaged ACs with the air cooled condensers are used more commonly than the ones with water cooled condensers since air is freely available it is difficult maintain continuous flow of the water.
The cooling unit comprising of the expansion valve, evaporator, the air handling blower and the filter are located on the floor or hanged to the ceiling.
The ducts coming from the cooling unit are connected to the various rooms that are to be cooled.
WATER COOLED AIR CONDITIONER
Water cooled air conditioner is also called water cooled condenser as its function is to reject the heat that was absorbed by the refrigerant in the evaporator.
Water is used to cool the hot air refrigerant(180°F or 82°C) from the compressor by pumping counter-flow water in the condenser.
The water used can be a wastewater system in which the water is thrown away into the drain after being used.
Wastewater system is not encouraged as it is wasteful and many states prohibit its use.
A better option but higher cost is to recirculate the water by using a cooling tower. The cooling tower will reject the heat from the water by forced draft or natural draft.
Advantages of packaged air conditioners
Space efficiency- Unlike split systems units, all components of complete heating and cooling system are contained in one location, making package units ideal for scenarios in which indoor space is at a premium.
Energy efficient heating and cooling performance- All package units now offer 13 SEER or higher cooling performance. Gas package units offer 80% AFUE heating performance or better.
Low initial investment- Manufacturers can carefully match component capacity and efficiency to maximize performance in a tightly integrated cost effective package.
Quick installation- Since all components are factory preassembled little on-site fabrication is necessary thereby eliminating many of the challenges of split system installation.
Aesthetics- Package units have virtually zero living or commercial space requirements.
Safety- Package units are installed by certified professionals who understand the technical challenges of constructing a gas supply system high voltage wiring, high pressure refrigerant lines and routing critical condensate lines.
A simple installation process
Portability for flexible air conditioning
A lower price than other models
No building work required
Installation and assembly labour charges are less.
Duct work is eliminated.
Units can be started or stopped easily.
Easy maintenance.
Individual room control is possible.
Failure of unit only affects one area, unlike the failure of central system, which affects entire building.
Disadvantages of packaged air conditioning
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