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Emerson
 
Window-Type
The window-type A/C is a one-piece machine, with the outdoor and indoor parts in one case. Application is limited to room A/Cs given its small capacity (most below 5000W).
Advantages
• Initial cost is very low
• Quick and easy installation
Disadvantages
• High noise
• Small capacity range
• Large temperature fluctuations
• Air delivery narrow relative to other A/C types
• Aesthetically unpleasant |
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Single -Split Wall- Mounted
The single-split wall-mounted A/C is a common residential A/C type in Asia, with an outdoor unit (holding the compressor) split from the indoor unit (evaporator). Like the window-type, its application is limited to the room A/C given the small capacity (most below 5000W).
Advantages
•Initial cost is low
•Installation is simple
•Noise is lower than window-type as outdoor unit is split
•Air delivery is wider than window-type
Disadvantages
•Small capacity range
•Large temperature fluctuations for fixed speed systems
•Piping between outdoor and indoor unit can only extend a few meters
•Aesthetically unpleasant outdoor unit |
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| PAC or Packaged A/Cs are also single-split systems but with a standing rather than a wall-mounted indoor unit. It has a higher capacity than the wall-mounted A/C (>5000W) and is suitable for large residential or small commercial spaces. |
Advantages
•Installation is simple
•Low initial cost for its capacity
•Deliver air over longer distances than wall-mounted or window
Disadvantages
•Takes up a large amount of floor space
•Large temperature fluctuations for fixed speed systems
•Aesthetically unpleasant outdoor unit
•Piping between outdoor and indoor can only extend a short distance. |
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| Rooftops are a self-contained, air-conditioning unit ranging 5 to 100 kW that provides cooling through ductwork. The rooftop unit is an air-cooled condensing unit and is installed onto the roof top to maximize the usage of the roof space and hide them from sight. |
Advantages
•Fresh air is easily introduced to the space
•Multiple units can be used to provided zone control
•Relative ease in installation
•Low equipment and installation cost
Disadvantages
•Poor part load efficiency for fixed speed units
•Being situated on the roof, efficiency is affected by very hot ambient conditions
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| Close-control air conditioning products are designed to maintain the optimum temperature and humidity conditions required by electronic systems all year round. High Performance Air Conditioning products range from packaged and split air conditioning units to large rooms, cooling units and chillers. |
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Central A/C refers to any system where single condensing units can simultaneously cool/heat more than one room. Essentially, a single condensing unit drives the whole refrigeration cycle for a central A/C, and the cooling/heating work derived from this cycle is sent to multiple rooms via various possible medium, including air, water, and refrigerant. Due to the need to cool and heat multiple rooms from a single driving source, the design of central A/Cs require a lot more consideration in terms of load calculations and piping needs.
Capacity range for central A/Cs is very wide, from small residential types (as low as 7100W) to large commercial types for entire buildings. Given this wide range, the range of central A/C types is also wider than the other A/Cs, including window-type, single-split wall-mounted, and packaged A/Cs. |
Advantages
•More aesthetic with outdoor unit(s) centralized in one case/area and hidden indoor units
•Piping can extend over longer distances
•Centralised control and maintenance
•Premium image
•Tight temperature control and hence greater comfort using VRF systems
•High energy savings when using VRF systems
Disadvantages
•Installation is complex with hidden piping
•Higher initial costs
•Require higher expertise level to maintain and repair
•Non-modulated types cannot separately control temperature in individual rooms
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Central A/C is one type gaining in popularity for residential use, and is a good choice in cases where multiple rooms exist and floor area is above 100 m2.
In choosing a suitable central A/C, we need to further compare the various central A/C sub-types. Look at the current market, we find three main types of central A/C (by medium of heat transfer): air duct type, water chiller, and VRF. |
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Air Duct Type
• Uses air as medium of heat transfer to condition individual rooms
• A duct type system is composed of a central condensing unit, heat exchangers, and centralized fan to move the air through ducts to move the cooled air and introduce fresh air
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Water Chiller
• Commonly used for large commercial application however smaller systems are used now for residential applications
• Water serves as the medium of heat transfer in a chiller system
• For small applications, water is cycled through the rooms across fan coil units to deliver cooling / heating into the room
• For larger applications, water exchanges heat in a centralized air handling unit to deliver cool / warm air across the air duct system |
VRF (Variable Refrigerant Flow)
VRF Central A/C system uses refrigerant as the medium of heat transfer to individual rooms. This type of system is generally suited for residential or small commercial application, but multiple systems can be pieced together to cover a larger area.
Current applications of VRF system apply modulation in one form or another. Copeland Digital Scroll is one of these forms, and is the latest technology in the market. Other variable capacity forms include the inverter technology and hot bypass.
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