NATE Air Distribution 1

Question 1

What does external static pressure (ESP) measure in an HVAC duct system?

Accepted Answer

Total resistance to airflow the blower must overcome, measured in inches of water column

Answer

Velocity of air at the supply registers

Answer

Duct leakage to outside

Answer

Return air CO2 concentration

Question 2

What tool is used to measure air velocity in a duct or at a register?

Accepted Answer

Anemometer or flow hood

Answer

Manometer

Answer

Psychrometer

Answer

Combustion analyzer

Question 3

What is Manual J used for in residential HVAC design?

Accepted Answer

Calculating heating and cooling loads for a structure

Answer

Duct sizing calculations

Answer

Selecting refrigerant type

Answer

Sizing expansion valves

Question 4

What is the purpose of a balancing damper in a duct branch?

Accepted Answer

Adjust airflow to individual zones to balance the system and deliver correct CFM to each room

Answer

Prevent backdrafting

Answer

Filter particulates from the airstream

Answer

Reduce duct noise

Question 5

What condition does a very high return static pressure typically indicate?

Accepted Answer

Restricted return airflow due to clogged filter, blocked return grilles, or undersized return duct

Answer

Oversized ductwork

Answer

Excessive supply air

Answer

Refrigerant overcharge

Question 6

What does ACCA Manual D provide for HVAC installations?

Accepted Answer

Procedures for residential duct system design and sizing

Answer

Equipment selection guidelines

Answer

Commissioning and startup procedures

Answer

Indoor air quality standards