User:Egnerb6/sandbox

HVAC Systems
HVAC Systems, or Heating, Ventilation, and Air Conditioning Systems is the system employed in almost all buildings that serve the purpose of indoor climate control. Their main purpose is to maintain air temperature and air quality in residential buildings, industrial buildings, and other buildings where people live and work. The Heating and Air Conditioning aspects of HVAC are fairly self-explanatory and deal mainly with the temperature inside the building. The Ventilation aspect of HVAC deals with the air quality in a given space and is key to maintaining a safe environment by eliminating odor, smoke, dust, and harmful chemicals such as CO2.

History
HVAC systems came around for the first time in the early 1900s as a result of many inventions that came out of the Industrial Revolution. The inventions were based on the findings of scientists from long ago, such as Michael Faraday and James Joule (1). But the actual equipment and processes that are used in the systems were created by people such as Willis Carrier and Reuben Trane, who still have HVAC systems companies named after them to this day (1).

Heating
The need for a heating system inside of a building has been around forever. In the past, fires were the most common way to warm up indoor climates, however this led to problems during the Industrial Revolution where it was not always safe to have open flames. This developed the need for a system that would warm up the air indoors while minimizing the safety risks.

Equipment
For heat generation, the main piece of equipment used is typically a furnace. Every furnace consists of 4 parts; burners, heat exchangers, a blower, and a flue (2). The burners are used to burn different types of fuel in order to create a heat source that is used to heat up the air supplied by the blower as both the air and the heat source are passed over the heat exchanger. This air that has been heated up, is then distributed throughout the building through a system of ductwork inside the building/home (2).

Ventilation
Ventilation serves the purpose of maintaining a safe and comfortable air quality throughout the area that is being heated or cooled. There are many rules and regulations set out by national and state governments that dictate certain percentages of allowable chemicals in the air such as smoke, dust, certain bacteria, and carbon dioxide (1). Ventilation systems were created to allow for an easily controlled and monitored way of making sure these percentages stay in the allowed zone.

Equipment
Ventilation systems are generally tied into the same duct work that is used to supply hot and cold air to a building. However, instead of equipment to cool or heat the air, there is generally just an inlet or exhaust fan that will either force air into the building, or force air out of the building (1).

Air Conditioning
Air conditioning serves the opposite purpose as a heating system and is used primarily to lower the air temperature inside of a residential or industrial building. In old times, this was accomplished by taking massive blocks of ice and passing air over them to cool down the air that was being distributed to the building. This was a very inefficient way of cooling a building and the need for a more efficient system caused the innovation that brought us modern air conditioning.

How it Works
The most common way to air condition buildings are small air conditioning units for residential purposes, and large industrial chillers for larger applications (3). Both function the same way, the scale is just altered depending on the applications. They are very similar to boilers, but instead of a heat source, a refrigerant is compressed until it reaches a desired temperature (4). Then, similar to a boiler, air is forced across a heat exchanger where the refrigerant cools down the air (4). The air that is now cooled down to the desired temperature is then distributed throughout the building by duct work in order to control the temperature of the building (3).