Exam 37: Air Distribution and Balance

One reason for using an extended plenum system is to ____.

The pressure in a duct system is measured in ____.

Friction due to air rubbing the walls of the ductwork can be eliminated.

The forced-air system is different from a natural-draft system, where the air passes naturally over the conditioning equipment.

Galvanized sheet metal comes in several different thicknesses, called the ____________________ of the metal.

If the equivalent length of a transition piece of ductwork is 10 feet and the main duct in series with it is 20 feet, what is the length used to estimate the total frictional loss?

Explain the purpose of the supply duct.

A(n) ____ can be connected to measure the velocity pressure of the air moving in a duct.

A(n) ____ºF temperature difference from the inside to the outside of the duct is considered the maximum difference allowable before insulation is necessary.

The atmosphere exerts a pressure of ____ at standard atmospheric conditions.

If the velocity of air through an 8" x 20" duct is 700 fpm, how many cfm of air is being carried by the duct?

Duct systems can be plenum, extended plenum, reducing plenum, or perimeter loop.

The duct pressure equals the velocity pressure plus static pressure.

Describe a pitot tube.

Canvas collars are generally made of canvas rather than other materials such as rubber.

The ____ provides the pressure difference needed to force the air into the duct system, through the heat-transfer surfaces in the conditioning equipment, through the grilles and registers, and into the room.

What are the components that make up the forced-air system?

Adjusting the tension on the belt will alter the rate at which air is moving through the system but does not affect the amperage draw of the motor.

Flexible round duct comes in sizes up to about ____________________ in. in diameter.

Oversized duct systems cost more to fabricate and install and will also result in the slowing of the air as it flows through the duct.