The objectives of HVAC systems are to provide an acceptable level of occupancy comfort and process function, to maintain good indoor air quality (IAQ), and to keep system costs and energy requirements to a minimum.

Commercial heating, ventilating, and air conditioning (HVAC) systems provide the people working inside buildings with “conditioned air” so that they will have a comfortable and safe work environment.

People respond to their work environment in many ways and many factors affect their health, attitude and productivity. “Air quality” and the “condition of the air” are two very important factors.

By “conditioned air” and “good air quality,” we mean that air should be clean and odor-free and the temperature, humidity, and movement of the air will be within certain acceptable comfort ranges.

ASHRAE, the American Society of Heating, Refrigerating and Air Conditioning Engineers, has established standards which outline indoor comfort conditions that are thermally acceptable to 80% or more of a commercial building’s occupants.

Generally, these comfort conditions, sometimes called the “comfort zone,” are between 68°F and 75°F for winter and 73°F to 78°F during the summer. Both these ranges are for room air at approximately 50% relative humidity and moving at a slow speed (velocity) of 30 feet per minute or less.

An HVAC system is simply a group of components working together to move heat to where it is wanted (the conditioned space), or remove heat from where it is not wanted (the conditioned space), and put it where it is unobjectionable (the outside air).

The components in a typical roof-mounted package HVAC system below are:

1. An indoor fan (blower) to circulate the supply and return air.

2. Supply air ductwork in which the air flows from the fan to the room.

3. Air devices such as supply air outlets and return air inlets.

4. Return air ductwork in which the air flows back from the room to the mixed air chamber (plenum).

5. A mixed air chamber to receive the return air and mix it with outside air.

6. An outside air device such as a louver, opening or duct to allow for the entrance of outside air into the mixed air plenum.

7. A filter section to remove dirt and dust particles from the air.

8. Heat exchangers such as a refrigerant evaporator and condenser coil for cooling, and a furnace for heating.

9. A compressor to compress the refrigerant vapor and pump the refrigerant around the refrigeration system.

10. An outdoor fan (blower) to circulate outside air across the condenser coil.

11. Controls to start, stop or regulate the flow of air, refrigerant, and electricity.

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Mike Bishop7 said...

Thank you for sharing this article about the basics of a HVAC system with us. I was actually online looking at my options for hvac in Austin when I came across your blog. I'm definitely happy I did because I'm pretty lost when it comes to all of this. You have definitely helped educate me on the basics, thank you again for sharing this.

Robert said...

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Robert said...

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