Central Station Air Handlers Flashcards
List the seven functions of a central station air handler as defined by ARI
Circulating Cleaning Heating Cooling Humidifying Dehumidifying Mixing Air
True or False? A packaged air handler offers a wider size range with more features and flexibility than a central station air handler?
False
The size of a central station air handler is usually based on _____
the airflow through the unit and the cooling coil face area
Name the two most common types of casing construction used in central station air handlers
post and panel, structural panel
Which of the following features is NOT generally found on an air handler designed for out-door installation? A.) Sloped roof with standing seams B.) Air inlet hood or louvers C.) High-quality gaskets and seals D.) Single wall, modular construction
D
True or False? In a draw thru air handler, the cooling coil is located on the upstream or inlet side of the fan.
True
True or False? Forward-curved fans are designed to operate at higher static pressures than airfoil fans.
False
Which of the following statements are true regarding AMCA fan class:____ A.) a class I fan may be operated under Class II or Class III performance requirements B.) a class II fan may be operated under Class III performance requirements C.) A Class III fan may be operated under Class II performance requirements. D.) All of the above
C
Under identical operation conditions A.) L50 200,000 hours = L10 40,000 hours B.) L50 500,000 = L10 40,000 C.) L50 represent the period of time all bearings of that type or designed will survive without fatigue failure D.) none of the above.
D
Which of the following air handler design features would more likely be found on a fully custom outdoor air handler than a standard central station AHU? A.) Sloped roof with standing seams B.) Outdoor intake hoods C.) Service and maintenance vestibules D.) G-90 galvanized casing panels
C
True or False? A filter with a MERV 15 rating is likely to be a 2-inch deep flat panel filter
False
In a VAV system, which type of fan wheel could be operated without fan volume control (allowed to ride the fan curve)?_____ A.) Forward-curved B.) Backward-inclinedC.) Airfoil D.) Plenum
A
Which types of energy recovery devices commonly provide both sensible and latent heat recovery? A.) Energy recovery wheels B.) Heat pipes C.) Run-around loops D.) fixed-plate heat exchangers
A
True or False? A dual-duct unit is a specific blow-thru configuration that can deliver cold and neutral or hot air simultaneously.
True
True or False? In a multizone air handler, the fan and cooling coil are always selected based on the instantaneous block load of the area served by the air handler.
False
The base placement of an ultraviolet light germicidal lamp (UV-c) within an air handler is immediately ____ A.) downstream of a cooling coil B.) upstream of a filter section C.) downstream of a heating coil D.) downstream of a mixing box
A
Face and bypass dampers. A.) may be used as a means of capacity control for both heating and chilled water coils B.) minimize the possibility of coil freeze-up in cold climates C.) are not recommended with direct expansion cooling coils D.) all of the above.
D
True or False? VFD has replaced IGV (inlet guide vanes) as the most common method of fan volume control.
True
For a coil constructed of the same materials and face area, rank the following factors in order of their impact on cost, from highest to lowest: fin spacing, circuiting, rows.
rows, fin spacing, circuiting
The primary reason for the recent market trend toward double-wall air handlers is:
double wall air handlers are perceived as higher quality
