Ventilation and Air Distribution Flashcards
6 cards from real HVAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Ventilation and Air Distribution flashcards as text
What is the purpose of a Variable Air Volume (VAV) box in a commercial HVAC system?
Answer: To vary the volume of conditioned air supplied to a zone based on its load
A VAV box modulates the volume of air supplied to a zone by adjusting a damper, allowing independent temperature control of multiple zones from a single central AHU.
What instrument measures air velocity in a duct or at a register?
Answer: Anemometer or velometer
An anemometer or velometer measures air velocity in feet per minute (FPM), which can be used to calculate airflow volume (CFM) when combined with the duct area.
What does MERV stand for in relation to air filters?
Answer: Minimum Efficiency Reporting Value
MERV (Minimum Efficiency Reporting Value) is a standard scale from 1-16 that rates how effectively an air filter captures particles of various sizes.
What is duct leakage testing used to determine?
Answer: The amount of conditioned air escaping through gaps and holes in the duct system
Duct leakage testing measures how much conditioned air is lost through unsealed joints, connections, and holes in the duct system, which wastes energy and reduces comfort.
In HVAC, what does the term 'throw' refer to when selecting supply air diffusers?
Answer: The horizontal distance the supply air travels before its velocity drops to 50 FPM
Throw is the horizontal distance that the primary air stream from a diffuser travels to reach a terminal velocity (typically 50 FPM) before mixing with room air.
What is an economizer in a commercial HVAC system?
Answer: A control system that uses cool outdoor air for free cooling when conditions allow
An economizer uses outdoor air for free cooling when outdoor conditions (temperature and/or enthalpy) are favorable, reducing mechanical cooling energy consumption.