Proprietary Air Distribution Systems
Proprietary air distribution systems are available from several manufacturers to provide supplementary heating or cooling in existing installations. They are also available as a complete heating and/or cooling system for installation in a structure where none previously existed or in which the existing system is clearly inadequate. They can also be used in new construction.
The Dunham-Bush Space-Pak air distribution system illustrated in Figure 7-29 is an example of a proprietary system that provides total comfort conditioning, including heating, cooling, air cleaning, and humidifying.
The Dunham-Bush air distribution system is generally an attic or overhead installation, but it may also be installed in basements or any other suitable area with no impairment of its operating performance.
Attic or overhead installation requires the construction of a mounting platform for the blower unit (see Figure 7-30). It is recommended that isolation pads or strips be placed between the blower coil unit and the mounting platform to prevent vibration transmission through walls or floors (see Figure 7-31). If the blower coil unit is
suspended from a ceiling, then both the blower coil and the electric heater are mounted on separate platforms.
The supply air is moved through a 7-inch insulated plenum duct with 2-inch insulated flexible tubing runs to air outlets. All components in the Dunham-Bush air distribution system snap or twist together. As in all duct systems, the number of tees and elbows should be limited to as few as possible in order to keep system pressure drop on larger layouts to a minimum.
A blower coil unit and an attached electric heater (see Figure 7-32) provide either heat or cool air depending on the control setting.
A cross-section of a blower coil unit is shown in Figure 7-33. The float switch is used to interrupt compressor operation when the condensation level exceeds a normal operating level. A further safeguard would be to provide a secondary drain pan.