308A HVAC Ductwork Systems

Question 1

What is the primary function of a supply air duct in an HVAC system?

Accepted Answer

To deliver conditioned air from the air handling unit to occupied spaces

Answer

Supply air ducts deliver conditioned (heated or cooled) air from the air handling unit (AHU) to the occupied spaces throughout a building. They are a critical component of the air distribution system.

Question 2

What is the difference between a return air duct and an exhaust air duct?

Accepted Answer

Return air recirculates air back to the AHU for reconditioning, while exhaust air is expelled outside the building

Answer

Return air ducts bring room air back to the air handling unit to be reconditioned and recirculated. Exhaust air ducts remove air from the building entirely, venting it outdoors.

Question 3

What is the purpose of a 'plenum' in an HVAC duct system?

Accepted Answer

To serve as a large distribution or collection chamber that connects to multiple branch ducts

Answer

A plenum is a large chamber or box that serves as a central distribution point for supply air or collection point for return air. It connects the air handling equipment to the duct system.

Question 4

What is the standard gauge for residential HVAC ductwork made from galvanized steel?

Accepted Answer

26 to 28 gauge

Answer

Residential HVAC ductwork is typically fabricated from 26 to 28 gauge galvanized steel. These gauges provide adequate strength for the lower pressures found in residential systems while being economical.

Question 5

What is the purpose of turning vanes in a rectangular duct elbow?

Accepted Answer

To reduce turbulence and pressure loss by guiding airflow smoothly around the turn

Answer

Turning vanes are curved airfoils installed inside rectangular elbows to guide the airflow around the turn with minimal turbulence and pressure loss, improving system efficiency.

Red Seal Sheet Metal 308A Practice Test

Red Seal Sheet Metal 308A Practice Test

308A HVAC Ductwork Systems