Central Station Air Handlers

Question 1

List the seven functions of a central station air handler as defined by ARI

Answer 1

Circulating
Cleaning
Heating
Cooling
Humidifying
Dehumidifying
Mixing Air

Question 2

True or False? A packaged air handler offers a wider size range with more features and flexibility than a central station air handler?

Answer 2

False

Question 3

The size of a central station air handler is usually based on _____

Answer 3

the airflow through the unit and the cooling coil face area

Question 4

Name the two most common types of casing construction used in central station air handlers

Answer 4

post and panel, structural panel

Question 5

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

Answer 5

D

Question 6

True or False? In a draw thru air handler, the cooling coil is located on the upstream or inlet side of the fan.

Answer 6

True

Question 7

True or False? Forward-curved fans are designed to operate at higher static pressures than airfoil fans.

Answer 7

False

Question 8

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

Answer 8

C

Question 9

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.

Answer 9

D

Question 10

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

Answer 10

C

Question 11

True or False? A filter with a MERV 15 rating is likely to be a 2-inch deep flat panel filter

Answer 11

False

Question 12

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

Answer 12

A

Question 13

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

Answer 13

A

Question 14

True or False? A dual-duct unit is a specific blow-thru configuration that can deliver cold and neutral or hot air simultaneously.

Answer 14

True

Question 15

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.

Answer 15

False

Question 16

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

Answer 16

A

Question 17

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.

Answer 17

D

Question 18

True or False? VFD has replaced IGV (inlet guide vanes) as the most common method of fan volume control.

Answer 18

True

Question 19

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.

Answer 19

rows, fin spacing, circuiting

Question 20

The primary reason for the recent market trend toward double-wall air handlers is:

Answer 20

double wall air handlers are perceived as higher quality