Modern Ref. Assignment

Question 1

Air expands to fill a greater space as

a) RH increases
b) pressure drops
c) temp rises
d) all of the above

Answer 1

RH increases

Question 2

Return air inlets should be placed

a) near ceiling
b) along floor
c) minimum distance from supply duct
d) max distance from supply duct

Answer 2

near ceiling

Question 3

To bring fresh air into a building’s conditioned space and minimize how much it might affect indoor temperature, use a (n)

a) barometric damper
b) HRV or ERV
c) motorized damper
d) soffit vent

Answer 3

b

Question 4

Negative pressure in a building

a) enhances efficient of exhaust fans
b) helps keep out airborne pollen
c) makes fuel-fired appliances efficient
d) tends to bring in outside contaminants

Answer 4

d

Question 5

A system in cooling mode should provide at least __ cfm of air per person

Answer 5

15cfm

Question 6

Which shape of ducts provides the least resistance to airflow?

Answer 6

round

Question 7

Which of the following is true of sheet metal ducts

a) used for warm air distr.
b) coated with zinc
c) expand and contract as they heat and cool
d) all of the above

Answer 7

c

Question 8

The ratio of a duct’s wide side to its narrow side is called the

a) effective length
b) aspect ratio
c) throw
d) length ratio

Answer 8

aspect ratio

Question 9

A rectangular duct with a __ aspect ratio can hold the maximum amount of air using the minimum amount of material

a) 1:2
b) 2:1
c) 1:1
d) 3:1

Answer 9

1:1

Question 10

To prevent oil canning when a blower starts and stops, ___ any large panels of sheet metal ductwork

a) cross-break
b) doubly insulate
c) perforate with vent holes

Answer 10

a

Question 11

___ are usually used as covers for return air ducts and have no adjustments

a) diffusers
b) grilles
c) registers
d) dampers

Answer 11

grilles

Question 12

A __ damper is used in round ducts

a) butterfly
b) globe
c) multiple blade
d) split

Answer 12

butterfly

Question 13

A fire damper rated for a 2-hour to 4-hour hold is class

A
B
C
D

Answer 13

B

Question 14

Installing long-radius elbows in ducts

a) maximizes airflow turbulence
b) minimizes airflow turbulence
c) minimizes airflow velocity
d) all of the above

Answer 14

b

Question 15

Which of the following is a general guideline for duct design?

a) make duct runs as long as possible
b) whenever possible, install duct in end of plenum
c) install blower in central location
d) all of the above

Answer 15

c)

Question 16

Which of the following are not found on airflow friction charts?

Answer 16

heat load

Question 17

To determine the __ of a duct run, add the physical length of the ductwork to the effective length value for each fitting in the duct run.

Answer 17

effective length

Question 18

Duct air velocities above __ fpm can cause excessive noise

Answer 18

700

Question 19

The air flowing into a fan is called the __ draft

Answer 19

induced

Question 20

The ACCA developed Manual ______ to be used to design both the supply and return ducts of a building

Answer 20

D