Air Distribution Flashcards
6 cards from real NATE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Air Distribution flashcards as text
What does external static pressure (ESP) measure in an HVAC duct system?
Answer: Total resistance to airflow the blower must overcome, measured in inches of water column
ESP is the sum of supply and return static pressures and indicates how hard the blower works against the duct system resistance.
What tool is used to measure air velocity in a duct or at a register?
Answer: Anemometer or flow hood
An anemometer measures air velocity in feet per minute (FPM); a flow hood captures total CFM at a register directly.
What is Manual J used for in residential HVAC design?
Answer: Calculating heating and cooling loads for a structure
ACCA Manual J is the industry-standard load calculation procedure that determines the BTU capacity required to heat and cool a home.
What is the purpose of a balancing damper in a duct branch?
Answer: Adjust airflow to individual zones to balance the system and deliver correct CFM to each room
Balancing dampers restrict airflow in over-supplied branches, diverting more air to under-supplied areas for proper room-by-room comfort.
What condition does a very high return static pressure typically indicate?
Answer: Restricted return airflow due to clogged filter, blocked return grilles, or undersized return duct
High return static pressure means the system is starved for return air, which reduces airflow and increases strain on the blower.
What does ACCA Manual D provide for HVAC installations?
Answer: Procedures for residential duct system design and sizing
Manual D provides the calculations and procedures for designing duct systems that deliver the correct airflow to each room based on Manual J loads.