Understanding the function of HVAC and how it works

HVAC stands for heating, ventilating and air conditioning; it performs heating and cooling for commercial, residential and industrial buildings. It can also provide fresh outdoor air to lighten interior air contaminants as occupant’s odor, VOC’s compounds that eliminates from interior furnishings, chemicals used for cleaning. A system that is properly designed will provide a indoor environment that is comfortable all round the year.

How does my AC work?

What an air conditioner does is that it simply cools and rejects humidity the air and circulates by a cold coil. The indoor coil is an air-liquid heat exchanger with few tubes that spreads liquid by the coil. Tubes those are connected with finned surfaces rises the whole area of cold surface therefore increasing the heat transfer features between the air passing by the coil and liquid passing by the coil. It totally depends upon which type of liquid you have selected. DX as in Direct-expansion material uses refrigerant for the liquid medium.

Types of AC systems in the market

Cooling only split-system

It is a combination of both an indoor unit and an outdoor condenser. The indoor air handling system has a air fan and an air-to-refrigerant heat exchanger and expansion device. The condenser is made of a compressor along with condenser coil. Basically these split systems are for residential and small commercial usage. These systems are very energy efficient of all the available systems.

Cooling only packaged-system

It is a system in a single unit containing all elements available in split system. Because it is a package it is placed outside the building and the air is circulated through ducks. This can be used for interior heating purposes also by electric or gas heating. These units have SEER ratings from 10 to 18 usually.

Heat pump

This system is very similar to cooling only system but has one exception. This has a special valve in the refrigeration pipe that allows to operate in reverse the cycle. Cooling system helps to make the interior cool and eliminates outdoor heat. Indoor air can be cool by a heat pump also since the valve is in reverse; it makes the indoor air warm. One can also use an extra electric heater to help the heat pump when the outdoor temperature is low, in winter it requires defrost. By the time of defrosting electric heater is the only thing for keeping the interior warm.

Chilled water system

In this system, liquid is circulated all over the building to chilled water coils. Because the liquid is required to be at cold temperature it requires a cooling plant.

Window air conditioner

As the name suggests, window air conditioner is basically a air conditioner which is installed in a window. It is purposely for small areas. These air conditioners are invented for both cooling and heating. For fresh outdoor air can be provided by optional damper. 

Packaged terminal heat pump

This system is very similar to window air conditioner. This is basically installed in outdoor wall sleeves, school classroom, and hotel etc. packaged terminal heat pump is self contained and requires an electric connection. But this system has some draw back like high maintenance; relatively short life is the big issue.