Deck 50: Commercial Rooftop, Packaged, Variable Refrigerant Flow, and Variable Air Volume Systems

Question 1

By utilizing a strategy called demand control ventilation, DCV, the amount of outside air being brought into the building can be varied based on the actual occupancy level in the structure.

Answer 1

True

Question 2

The term enthalpy refers to the total heat content in the air, which accounts for both the temperature (sensible heat portion) and the moisture content (latent heat portion) of the air.

Answer 2

True

Question 3

In order to deliver different volumes of air to various areas in an occupied space, the blowers used on VAV systems must be able to modulate their openings to accommodate the changing needs of the system.

Answer 3

False

Question 4

Rooftop units are often positioned ____ the space that is to be served by the equipment.

A) directly below
B) directly behind
C) directly adjacent
D) directly above

Question 5

It is good field practice to double-check and possibly triple-check the ____ decision, since the cost of repairing an improperly cut roof can be very high.

A) location
B) size
C) capacity
D) operational

Question 6

The rooftop unit houses the fans and blowers that move air through the heating and cooling portions of the unit but not through the condenser.

Question 7

If the curb is mounted as part of a new construction process, it can be assembled and installed as soon as the ____ support system is in place.

A) walls
B) ceiling
C) roof
D) utility

Question 8

The fans that move air through the air-cooled condensers are of the ____-type.

A) propeller
B) squirrel
C) cage
D) push

Question 9

The unit's location should be carefully selected so the system's operation is not adversely affected by air being able to ____ the condenser coil.

A) bypass
B) circulate back through
C) recirculate
D) induce cooling in

Question 10

Gasketing materials and foam panels that are shipped with the curb are not part of the curb and should be discarded.

Question 11

Some roofs are bonded, which are roofs that carry a written warranty or insurance policy that protects the building owner in the event damage from leaks occurs.

Question 12

The curb's cross braces are intended to support the duct connections to the unit, but not the entire air distribution system.

Question 13

It should be noted that, in most cases, the supply and return ductwork must be attached to the ____ before the unit is set in place.

A) boom
B) package
C) load
D) curb

Question 14

Be sure to provide proper and adequate support for the duct system according to ____.

A) installation instructions
B) local building codes
C) state building rules
D) environmental regulations

Question 15

Improper clearances do not affect the ability of service personnel to perform their jobs adequately.

Question 16

Package units are factory-assembled, factory-charged, self-contained systems that have all of the major system components contained in a single housing.

Question 17

By raising the forearm in the air, index finger pointing upward and holding the hands straight, the operator will know to raise the cable on the crane.

Question 18

Curbs can be prefabricated, but many larger curbs are shipped unassembled.

Question 19

Although packaged air-conditioning equipment comes precharged with refrigerant and no field piping must be done, the installation of a rooftop package unit involves many steps and can be very dangerous.

Question 20

The amount of refrigerant indicated on the ____ is the total refrigerant charge for the unit, not simply a holding charge as in the case of a split-type system.

A) bill of lading
B) compressor
C) nameplate
D) blower

Question 21

The economizer is able to increase or decrease the amount of outside air that is brought into the structure with two ____.

A) blowers
B) dampers
C) valves
D) diverters

Question 22

Many rooftop package units are equipped with multiple ____________________ fans.

Question 23

Explain the term "free cooling."

Question 24

The temperature sensor used in chilled-water VAV systems to detect when the outside air is cold enough to cause freezing, is typically called a(n) ____________________.

Question 25

Name the four common types of VAV boxes.

Question 26

How do variable refrigerant flow (VRF) systems modulate the volume of refrigerant that is pumped through the system?

Question 27

With both fists in front of the body, pointing the thumbs outward tell the crane operator to ____ the boom.

A) retract
B) rotate
C) extend
D) lower

Question 28

The water coil in a dry cooler can contain 100% water or can be a mix of water with  ____________________.

Question 29

When multiple rooftop units are used to condition the air in a building, it is common practice to label the units and their corresponding ____________________.

Question 30

What are some drawbacks of adding more antifreeze than needed to prevent freezing in the chilled water piping system?

Question 31

A frame that is used to mount HVAC equipment is called a(n) ____________________.

Question 32

____ are intended to help provide the correct amount of ventilation and also help reduce cooling costs by allowing outside air to be introduced to the conditioned space when conditions are correct.

A) Minimizers
B) Maximizers
C) Economizers
D) Recirculators

Question 33

An enthalpy sensor includes solid state temperature and ____ sensors.

A) entropy
B) barometer
C) pressure
D) humidity

Question 34

Explain the purpose of the relief fan.

Question 35

By tapping his fist on his ____, the crew member is telling the crane operator to use the main hoist.

A) head
B) wrist
C) arm
D) shoulder