Unitary systems are packaged units, in which, all the equipments and controls, fulfilling the requirements of air conditioning, are assembled in a single casing with decorative covering. Thus, unitary air conditioning systems are called as “factory-assembled units having internal wiring, controls and piping”. These units are manufactured in a wide range of types and capacities. They are installed within or near the space to be conditioned. These units are common y preferred for 1/2 tonne to 15 tonnes capacity or above with air flow of approximately 200 m3 /minute. Recently developed units having 100 tonnes capacity are also manufactured and used. Unitary air conditioner offers the advantage of ease of selection, low initial cost, ease of installation and removal. With proper selection and good control, it involves relatively low operating costs.
Types of Unitary Air Conditioning System
Broadly, the unitary air conditioner is classified into two categories.
Window Air Conditioner
They are self-contained units of small capacity ranging from 1/2 TOR to 3 TOR, and are mounted in a window or through the wall. They are used to obtain conditioning of air of one room only. If the room is bigger in size, two or more units can be installed.
Vertical Packed Units
They are also self-contained units of bigger capacity ranging from 5 TOR to 20 TOR and are installed adjacent to the space to be conditioned. They are very useful for air conditioning of restaurant, bank or small offices. The vertical packed systems are further categorized as,
- Self-contained or single-package units.
- Split system or split-package units.
For the split unit, it is necessary to connect the insulated tubing/piping carrying refrigerant across the indoor and the outdoor sections.
Advantages of Unitary Air Conditioner System
- Low installation cost including labour charges of assembling and fitting the unit.
- Duct-work is eliminated.
- Individual room-temperature control is a specific feature of this system.
- In unitary system, exact requirement of each separate room is met, whereas, in central air conditioning system, the indvidual needs of separate rooms cannot be met.
- Failure of the unit leads to stop air conditioning of only one room, whereas the failure of central air conditioning system leads to stop air conditioning of all rooms and entire space to be conditioned.
- In case of unitary air conditioning, only those rooms, which need cooling, will have their units running, whereas the central air conditioning system will have to run all the time for the sake of few rooms, which need cooling.
Disadvantages of Unitary Air Conditioner
- Very limited options are available while selecting the unit for the given application area.
- Components of system, such as evaporator condenser, fans, compressor, controls must be selected as per the required comfort conditions. But, very few options are available with respect to size and cost of individual components.
