HVAC Systems Analysis Flashcards
7 cards from real INTERNACHI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 HVAC Systems Analysis flashcards as text
Which condition is most commonly associated with a failed or dirty flame sensor in a gas furnace?
Answer: The furnace lights briefly then shuts off after a few seconds
A dirty or failed flame sensor cannot confirm ignition, causing the control board to shut off the gas valve within seconds as a safety measure.
What is the primary purpose of a whole-house bypass humidifier bypass duct?
Answer: To route a portion of supply air through the humidifier pad and back to the return plenum
A bypass humidifier draws warm supply air through a water-saturated evaporative pad and returns the humidified air to the return plenum for distribution.
A home inspector observes that a split-system AC compressor is located in a utility closet inside the home. What is the most significant concern?
Answer: The condenser coil cannot reject heat properly indoors, making the system ineffective
Air-cooled condensing units must be outdoors to reject heat to the atmosphere; placing one indoors prevents proper heat rejection and will cause the system to fail.
Which HVAC filter rating system measures a filter's ability to capture particles of specific sizes?
Answer: MERV rating
MERV (Minimum Efficiency Reporting Value) rates filter efficiency from 1–16 based on the percentage of particles captured at different sizes.
During an inspection of a packaged rooftop HVAC unit, what should the inspector note about the unit's curb?
Answer: Whether the curb is properly flashed and sealed to prevent roof leaks
Improper flashing or sealing around a rooftop unit curb is a leading cause of roof leaks and should be reported if deteriorated or improperly installed.
What is the typical expected service life of a residential gas furnace?
Answer: 15–20 years
The average service life of a residential gas furnace is approximately 15–20 years, with proper maintenance extending that range.
When inspecting a zoned HVAC system, what component regulates airflow to individual zones?
Answer: Motorized dampers controlled by zone thermostats
Motorized dampers in the ductwork open or close based on signals from individual zone thermostats, allowing each zone to be heated or cooled independently.