HVAC Systems

What are packaged HVAC systems?

Packaged HVAC systems consist of pre-assembled, off-the-shelf equipment that provides space heating, cooling and ventilation. A wide range of configurations are available, including both traditional and heat pump systems. Packaged systems typically fall into three general categories:

• Single package rooftop systems. These systems consist of a single rooftop-mounted unit that contains all mechanical elements of the HVAC system, including compressors, condensers and evaporators. The unit also includes a supply fan and filter system that connect to the building's new or existing ductwork to provide air to the conditioned space.
• Split systems. These systems include a typically rooftop-mounted unit that contains the compressor and condenser elements, but the evaporators, supply fan and filter system are housed in a separate inside unit for greater efficiency.
• Package terminal air conditioners (PTAC), also called "through-the-wall" air conditioners. These relatively small systems are like a commercial quality version of residential window-mounted air conditioners (although they are actually mounted at floor level in a sleeve passing through the building wall). The units are totally self-contained, requiring no external ductwork.

Multiple packaged HVAC units are usually required to serve an entire building. This can be an advantage, since each system can be well matched to the interior space that it serves.

Packaged HVAC units are used in almost all classes of commercial buildings. However, in some situations, custom or semi-custom HVAC systems are a better solution due their higher capacities and, in some cases, even greater efficiency. 

What are some common options for packaged HVAC systems?

Most manufacturers of packaged HVAC systems offer useful options for their systems, some of which can be installed as retrofits to existing packaged systems. Some typical options include:

• Enhanced temperature and time controls. Highly programmable controls are available that can operate HVAC systems based on building occupancy schedules, including nighttime temperature setbacks. This can significantly reduce energy costs.
• Economizers. Some packaged systems support economizers that use dampers and related controls to allow outside air to be used for cooling when outdoor temperatures are moderate. This "free cooling" can provide significant energy savings in some climates.
• Indirect evaporative cooling. Some packaged HVAC systems support modules that circulate water over a heat exchanger to use the cooling effect of evaporating water to pre-cool air entering the system's cooling sections. This can provide significant energy savings in some climates.
• Powered exhaust fans. Some packaged HVAC systems support powered exhaust fans that help maintain desired pressurization of the building (or of selected areas in the building).