HVAC controls (Heating, Ventilating and Air Conditioning) are an integral part of a building's system. All systems act in accordance with a few basic principles. These design principles allow for no deviation because any alteration can result in drastic swings in either heating or cooling operations. |
Automatic HVAC Controls
The operating capacity of the central air system is configured in a way to effectively manage the most extreme conditions. Operations generally consist of part load/off (compressor) design due to variables such as solar loads, building occupancy, ambient temperatures, and equipment and lighting loads that fluctuate throughout any 24-hour period.
The two types of systems are either self-contained unit packages or central systems. The unit package is simply one unit whose purpose is to convert an energy source, most commonly electricity or gas, to a form that provides heating and cooling to the space in which it resides.
Examples of single unit packages are plentiful and can be seen in rooftop installations, air conditioning units in rooms, and in air-to-air heat pumps. The air-to-air heat pumps are for use in milder climates only because they work by using the difference between the outdoor and indoor temperatures to heat and cool an interior space.
The central form of central air operations converts the energy source in the same way as the single unit package, but instead of just one unit, the conversion takes place in a central location in the building and distributes the cooling and heating properties using a form of thermal energy. The central system design depends on various nodes or subsystems placed throughout the building in strategic locations similar to a computer network.
The typical central operation uses a combination of hot and cold water distributed to a network of multiple fans and placed in appropriate areas throughout the interior of the building.
HVAC Controls and Strategies
The simplest of the HVAC controls is a cycling or on/off switch that meets partial load requirements. If a building only requires half of the energy capacity the system is designed to deliver, it will run for a few minutes, turn off for a few minutes, and keep cycling until the energy load within the building increases.
Locations in the System where Controls are Distributed
There are three main areas along the system where HVAC controls are placed in most engineering designs.
- Main mechanical gear such as chillers, boiler, hot water generator, heat exchanger, and pumps - The AHU's or Air Handling Units that are responsible for heating, cooling, humidifying, dehumidifying, ventilating, and filtering the air before distributing the air to different sections of the building - Individual room modules that are a part of each design. This equipment includes fan coil units, variable air volume systems, terminal reheat unit ventilators, exhausters, and zone temperature humidistat
This is only a brief overview of the intricate and complex feat of mechanical engineering that comprises heating and air conditioning.
The critical role that HVAC controls play in such a complicated engineering design should also be noted. All devices must be manufactured to the highest of standards and installed only by experienced, professional HVAC contractors. To do otherwise is to invite costly disasters to the building and possibly its inhabitants.
When considering HVAC controls, visit Energy Equipment and Control, Inc. Learn more about this product at http://www.energyequipment.com/.
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