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Fundamental Principles of HVAC Systems

Posted on 28 March 2018 by admin (0)

HVAC systems are the core of cooling and heating within homes and office buildings. Therefore, having an understanding of the fundamental principles of HVAC systems will help you to comprehend the basics of HVAC system operations. To understand the effective control of critical parameters such as air movement, humidity and temperature in a conditioned space, it is essential to be familiar with the processes and fundamental principles of HVAC.
The processes of Heating, Ventilation and Air Conditioning are:
1. Cooling: this is a decrease in temperature achieved by the removal of thermal energy from a conditioned space.

2. Heating: this involves the increase in temperature achieved by the addition of thermal energy to a conditioned space

3. Air Movement: this involves the control, transportation and supply of ample air through the ducts into a conditioned space so that the occupants of the space feel comfortable.

4. Humidifying: this process involves the addition of steam or water vapour to a space to increase the relative humidity of that space.

5. Dehumidifying: this is the opposite of the humidification process as it involves the removal of humidity or water vapour of a space.

6. Ventilating (the V in HVAC): this is a very important process in HVAC. It is the addition of fresh air from the outside to the inside without compromising gas ratios. In other words, it is the process of replacing or exchanging air in any conditioned space to provide high indoor air quality. Ventilation or ventilating involves oxygen replenishment, temperature control, and the removal of smoke, airborne bacteria, excessive moisture, heat, carbon dioxide, dust, and unpleasant smells.

7. Cleaning: the is also an important process in HVAC and it is otherwise referred to as Air Filtration. It involves the removal of smoke, contaminants, pollens and dust from the air inside a conditioned space.

Heat removal from an HVAC system (Cooling)
Removal of heat in simple term means an attempt to cool down. There are numerous practicable methods to get rid of heat from a residential or office building. The commonly known and utilized method is the use of Air Conditioners. This has, however, created a misconception that the use of ACs is the only means of removing heat from a building. To efficiently get rid of heat from a space, a heat pump can also be used. A heat pump offers a lot of advantages over a traditional Air Conditioning unit.
The various types of Air Conditioning Units that can be used for the removal of heat are:
• Split Unit
• Window Unit
• Chilled Water Air Conditioning System
• Direct Expansion ACs
• Hybrid Air Conditioners
• Portable Air Conditioners

Heat Addition to an HVAC system (Heating)
In HVAC systems, heat generation can take different forms. In some set-ups, furnaces are used while in some, boilers are employed. Furnaces generate heat through burning of materials and supplies the heat through the duct system. Boilers employ oil and gas to raise the temperature of water while a furnace utilizes propane or natural gas. Another heating option is the use of Hydronic Heating Systems (HHS). HHS makes use of underground pipes, made of flexible tubes, filled with glycol or water solution