Working spaces or indoor areas should provide thermal comfort along with high indoor quality air. HVAC stands for Heating, Ventilation and Air Conditioning, is a system in whole to provide healthy and comfortable internal conditions by removing hot air. All of the effectiveness of HVAC depends on its design. Importantly it is designed for minimal use of non-renewable energy and less water pollutant emissions.
HVAC systems are essential in a number of industries, and provide the atmosphere necessary for food to be kept fresh and to ripen so that it is safe to eat as well as flavorful, and is also known as climate control. Because certain types of plants prefer humidity levels of 50% or greater, in hot and dry environments quality HVAC systems are vital for creating an environment where fragile fresh produce can flourish.
Need for HVAC System
Need for HVAC can be for following listed uses like
- To improve air quality of the confined space for providing comfortable working environment to the workers,
- To regulate moisture in the processing area to minimize the growth of water activity in environment hence preventing the microbial growth
- To improve process quality, by providing contaminant free, filtered air in the processing room preventing any sort of contamination
- To maintain constant temperature throughout the year as there can be wide fluctuation in temperature during various time period of year. To keep uniformity of comfort level HVAC can be used.
Types of HVAC System
- Heating and Air Conditioning Split System: A wall mounted split system air conditioner consists of two parts; a wall mounted indoor unit and an outdoor unit. The indoor unit blows cool air into the room, and the outdoor unit dissipates the heat from the cooled area. Refrigerants are used to cool or heat the air.
- Hybrid Heat Split System: A hybrid heat system reacts to changing temperatures and automatically adjusts to the most efficient energy saving method available to heat or cool the space. It can be a fuel-saving alternative to traditional heating and cooling systems.
- Duct Free Split Heating and Air Conditioning System: Ductless free split-system air-conditioners have numerous potential applications in commercial buildings.
- Packaged Heating & Air Conditioning System: It has higher cooling or heating capacity and is usually able to cool an entire commercial building. The nominal capacities ranges from 3 tons to 15 tons. The conditioned air is transferred to the space to be conditioned through ducting which is usually hidden in the ceiling and wall of the building. The unit is placed outside the building, a special room in a building or even on top of a roof.
Components and working of HVAC System
- Thermostat–The thermostat is usually the most visible part of HVAC system. They are set at the most accessible part so that they can be changed according to need. When the ambient temperature becomes too cold or too hot, the thermostat will trigger the heat exchanger or the evaporator coil-condensing unit combo to begin circulating warmed or cooled air as per requirement.
- Furnace–The furnace is the key component of HVAC system. It requires the largest substantial space typically a special place designed for that purpose. Its function is to heat supply air which is to be distributed to various rooms of building via the HVAC. This heating process is accomplished using one of four possible heat sources combustion (burning natural gas, oil, coal, or propane), electric resistance, heat pump, or solar energy collected on site.
- Heat exchanger- The heat exchanger are inside furnace unit’s housing. This component switches on when the furnace is activated by thermostat to produce warmer temperatures. The heat exchanger pulls in cool air, heats it, and circulates the resulting heated air via ducts and out through the vents.
- Evaporator coil –It acts to cool the air when thermostat is set to lower temperatures. Located in a metal enclosure on the furnace’s exterior, to the top or side, the evaporator coil works similarly to an automobile radiator to produce cool air, which is then circulated through the ductwork.
- Condensing unit- It is connected to the evaporator coil. This unit are filled with refrigerant gas. When the refrigerant has been cooled to a liquid by heat exchanger with the exterior air, the condensing unit pumps the liquid to the evaporator coil to be evaporated into a gas.
- Refrigerant lines– The refrigerant lines carry a refrigerant substance to the condensing unit vaporized in the form of a gas, and return it to the evaporator coil in liquid form. These “lines” are actually narrow tubes manufactured from a durable heat- and cold- resistant metal such as copper or aluminum.
- Ductwork–Ductwork refers to the system of ducts that transports air warmed or cooled by the system to the various areas of building. They may be manufactured from steel, flexible plastic, polyurethane, fiberglass, or fabric.
- Vents- These are rectangular outlets which transfer the heated or cooled air from the duct system into the individual rooms. Made of high- and low-temperature safe metal, vents are located on or near the ceiling and are usually fronted with angled slats.
Air Handling Units:
Air handling unit is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork.