NATE Air Distribution 2

Question 1

What unit is used to measure duct air leakage during a duct leakage test?

Accepted Answer

CFM25 (cubic feet per minute at 25 pascals)

Answer

Duct leakage is expressed as CFM25, the airflow escaping through duct leaks when pressurized to 25 pascals above atmospheric pressure.

Question 2

What is the recommended duct sealing material for permanent duct repairs?

Accepted Answer

Mastic sealant or metal foil tape (UL 181 listed)

Answer

Mastic sealant and UL 181 listed foil tape are durable, code-approved methods; standard cloth duct tape dries out and fails over time.

Question 3

What MERV rating range is recommended for residential HVAC filters to balance filtration and airflow?

Accepted Answer

5–8

Answer

MERV 5–8 filters provide adequate filtration for residential equipment while maintaining sufficient airflow and avoiding excessive pressure drop.

Question 4

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

Accepted Answer

Serve as a pressure chamber that distributes or collects air from multiple duct branches

Answer

The supply plenum distributes conditioned air from the air handler to multiple duct branches; the return plenum collects air from return branches.

Question 5

What is the maximum recommended duct velocity for residential supply ducts to minimize noise?

Accepted Answer

700–900 FPM

Answer

Residential supply ducts typically target 700–900 FPM to balance duct size with acceptable noise levels.

NATE - North American Technician Excellence Practice Test