System Design Flashcards
7 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 7 System Design flashcards as text
What is the primary purpose of a Manual J calculation in HVAC system design?
Answer: Calculate heating and cooling loads for a building
Manual J is the ACCA standard method for calculating residential heating and cooling loads to properly size HVAC equipment.
In a forced-air system, what is the recommended maximum air velocity in main supply ducts to minimize noise?
Answer: 700–900 FPM
Main supply ducts are typically designed for 700–900 FPM to balance noise control with efficient air delivery.
Which HVAC system configuration uses a single outdoor unit connected to multiple indoor fan-coil units?
Answer: Variable refrigerant flow (VRF) system
VRF systems use one outdoor condensing unit connected via refrigerant piping to multiple indoor fan-coil units for zone-level control.
What does ACCA Manual D govern in HVAC system design?
Answer: Residential duct design
Manual D is the ACCA standard for designing residential duct systems, covering duct sizing, layout, and airflow distribution.
A building has a sensible heat ratio (SHR) of 0.70. This means:
Answer: 70% of the cooling load is sensible heat
SHR is the ratio of sensible cooling load to total cooling load, so an SHR of 0.70 means 70% of the load is sensible.
In hydronic system design, what is the purpose of an expansion tank?
Answer: Absorb volume changes as water heats and expands
An expansion tank accommodates the increase in water volume as it is heated, preventing excessive pressure buildup in a closed hydronic loop.
What is the design dry-bulb outdoor temperature used for in HVAC load calculations?
Answer: Determining the heating or cooling design load
The outdoor design dry-bulb temperature (from ASHRAE tables) represents worst-case conditions used to calculate peak heating or cooling loads.