Four requirements are the bases for any HVAC systems i.e. primary equipment, space requirement, air distribution, and piping. Primary equipment includes heating equipment such as steam boilers and hot water boilers to heating buildings or spaces, air delivery equipment as packaged equipment to deliver conditioned ventilation air with the use of centrifugal fans, axial fans, and plug or plenum fans, and refrigeration equipment that delivers cooled or conditioned air into space. There are cooling coils based on water from water chillers or refrigerants from a refrigeration process. Space is essential in shaping an HVAC system to be central or local. It requires five facilities like the following:
a. Equipment rooms: The total mechanical and electrical space requirements are between 4 and 9% of the gross building area. It is preferable to be centrally located in the building to reduce the long duct, pipe, and conduit runs and sizes, to simplify shaft layouts, and centralized maintenance and operation.
b. HVAC facilities: heating equipment and refrigeration equipment may perform their primary tasks of heating and cooling the building by using several facilities. The heating equipment requires boiler units, pumps, heat exchangers, pressure-reducing equipment, control air compressors, and miscellaneous equipment, while the 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 design of equipment rooms for placing the equipment should consider the size and the weight of equipment, the installation and maintenance of equipment, and the applicable regulations to combustion air and ventilation air criteria.
c. The HVAC fan equipment and other miscellaneous equipment are found in the fan room. The rooms should consider the size of the installation and removal of fan shafts and coils, the replacement, and maintenance. The size of fans depends on the required airflow rate to condition the building, and it can be centralized or localized based on the availability, location, and cost. It is preferable to have easy access to outdoor air.
d. Vertical shaft: this is used to provide enough space for air distribution and water and steam pipe
distribution. The air distribution contains HVAC supply air, exhaust air, and return air ductwork. Pipe distribution includes hot water, chilled water, condenser water, and steam supply, and condenser return. It also has the mechanical and electrical distribution to serve the entire building including plumbing pipes, fire protection pipes, and electric conduits/closets.
e. Equipment access: the equipment room should be such that it allows the movement of large, heavy equipment during the installation, replacement, and maintenance