Air Distribution Flashcards
As relative humidity increases, each pound of air will ____.
occupy a larger space
As the temperature rises for a pound of air at a set humidity level, its density ____.
decreases
The heat or energy stored within moisture in the air is ____ heat.
sensible
Temperature difference between return and supply air is greatest in ____ systems.
standard heating
Air delivered to a room from a supply duct is called ____ air.
primary
Throw is the distance that air entering a room travels from the duct outlet before it slows to ____ fpm.
50
A room will have ____ if there is more air leaving than entering.
negative pressure
Common automatic methods of bringing in fresh air into an average home’s conditioned space are.
Energy Recovery Ventilator
Heat Recovery Ventilator
Fresh Air Inlet Damper
A system in cooling mode should provide at least ____ of air per person.
15 cfm
Vented attics use what for ventilation?
Attic Fans
Louvers
Vents
Hot air rising in a vented attic can escape through what roof top vents?
Gable Vents
Ridge Vents
Roof Ventilators
The ratio of the duct’s wide side to its narrow side is the ____.
aspect ratio
The class of fire damper that can be used where a one-hour hold is required is a Class ____.
C
The class of fire damper that will hold back a fire indefinitely is a Class ____.
A
The class of fire damper that can be used a two-to four-hour hold is required is a Class ____.
B
The pressure difference between the blower inlet and outlet is called the ____.
external static pressure (ESP)
The amount of friction or resistance used to design the longest duct run is called ____.
available static pressure (ASP)
Effective length of duct run is calculated by adding the physical length of the ductwork and the effective length values of ____.
each fitting in the duct run
Friction loss is the ____ resulting from the air contracting the inside surface of the duct.
pressure drop
Friction loss is typically expressed in units of ____ 100’ of duct.
inches of water column
Device pressure loss may result from ____.
Air filter
Damper
Evaporator Coil
An axial fan uses a ____ fan.
propeller
A radial fan uses a ____ fan.
centrifugal
The pressure generated on the exhaust side of a fan is ____.
positive
The pressure generated on the at the air inlet to a fan is ____.
negative
The air feed into a fan is called ____ draft.
induced
The exhaust form a fan is called ____ draft.
forced
