Four requirements are the bases for any HVAC system.
They need primary equipment, space requirement, air distribution, and piping
A building's or space's primary equipment includes heating units like steam boilers and hot water boilers to provide heat, packaged units to provide conditioned ventilation air using centrifugal fans, axial fans, plug or plenum fans, and refrigeration units to provide cooled or conditioned air into space. It contains cooling coils that use either refrigerant from a refrigeration system or water from water chillers.
The need for space determines whether an HVAC system is local or central. It needs the following five facilities: Since the overall amount of mechanical and electrical space needed ranges from 4 to 9 percent of the gross building size, equipment rooms are needed. To minimize long duct, pipe, and conduit lengths and diameters, streamline shaft layouts, and allow for centralized maintenance and operation, it is desirable to situate the component in the building's center. HVAC facilities are necessary for heating, cooling, and refrigeration equipment to carry out their basic functions in a structure. While refrigeration equipment requires water chillers or cooling water towers for large buildings, condenser water pumps, heat exchangers, air-conditioning equipment, control air compressors, and miscellaneous equipment, the heating equipment needs boiler units, pumps, heat exchangers, pressure-reducing equipment, and other miscellaneous equipment. The size, weight, installation, upkeep, and relevant rules for ventilation air and combustion air should all be taken into account when designing equipment rooms to house both pieces of equipment. The HVAC fan equipment is located in fan rooms together with other equipment. The rooms should consider the size of fan shaft installation and removal, coil replacement, and maintenance. The size of the fans is determined by the airflow rate needed to condition the building, and it can be localized or centralized depending on availability, cost, and location. It is better to have simple access to the fresh air outside. Vertical shafts provide space for air distribution, water and steam pipe distribution, and electrical power distribution. Air from the HVAC system is delivered to air handlers in each room; return air from each room is drawn into the vertical shaft by a blower; hot water from the condenser coil is pumped through a hot water piping system; chilled water from the condenser coil is pumped through chilled water piping systems; condenser wastewater is pumped through condenser return piping systems, and steam supply piping accommodates the high-pressure steam. Equipment access: During installation, replacement, and maintenance, large, heavy equipment must be able to move freely within the equipment room. Air distribution can be used to increase comfort and improve efficiency in buildings. It includes air terminal units such as grilles and diffusers to deliver supply air into space at low velocity; fan-powered terminal units, which use an integral fan to ensure the supply of air to the space; variable air volume terminal units, which deliver a variable amount of air into the space; all-air induction terminal units, which controls the primary air, induces return air, and distributes mixed air into space; and air-water induction terminal units, which contains a coil in the induction air stream. All ductwork and piping should be insulated to prevent heat loss and save building energy. Building owners should consider adding ceiling spaces that can be used as return plenum areas to reduce return ductwork. Piping systems transport refrigerant, hot water, cooled water, steam, gas, and condensate to and from HVAC equipment in a direct, quiet, and affordable way. Piping systems can be divided into two parts: the central plant equipment room piping and the delivery piping. Piping may or may not be insulated based on existing code criteria.