Understanding HVAC systems
What is a HVAC System? A HVAC system is a heating, ventilation, and air-conditioning system. A system that does any one (or more) of those tasks is called a HVAC system.
The objective of an HVAC system is to ensure that an indoor environment is both safe and comfortable for humans. Safety here mainly concerns the Indoor Air Quality or IAQ, meaning that the indoor air should have enough oxygen and be free of noxious gases. Comfort of course is based on human perception, which can vary within bounds. ASHRAE (the American Society of Heating, Refridgeration, and Air-conditioning Engineers), defines comfortable air quality as one “with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.”
Although there are many ways in which to make an indoor space in a hot climate comfortable, we shall focus on the most common type of air-conditioning (AC) system found in buildings today. Before we discuss that, a quick word. Most AC systems work on one principle: when a fluid is compressed, it “throws away” the heat it contains, and when it expands, it absorbs heat from its surroundings. Therefore by alternately compressing and releasing a fluid, one can make it “absorb” heat from inside a building and release it outside.