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
What does AFUE measure in heating equipment?
Answer: Annual fuel utilization efficiency
AFUE (Annual Fuel Utilization Efficiency) expresses as a percentage how much of the fuel's energy is converted to usable heat over a heating season.
Which venting category applies to high-efficiency condensing furnaces with AFUE ≥90%?
Answer: Category IV (positive pressure, condensing)
Category IV applies to positive-pressure, condensing appliances like high-efficiency furnaces, which vent with PVC or CPVC pipe and produce acidic condensate.
An inspector observes ice forming on the evaporator coil of a central AC system. Which condition is NOT a likely cause?
Answer: Oversized ductwork
Oversized ductwork increases airflow, which would reduce icing; low refrigerant, restricted airflow, and operating below 65°F are all common causes of evaporator coil icing.
What is the function of a humidistat in an HVAC system?
Answer: It activates or deactivates the humidifier based on indoor relative humidity
A humidistat senses indoor relative humidity and signals the whole-house humidifier to operate when humidity falls below the set point.
During an HVAC inspection, what does a home inspector typically verify about the condensate drain system?
Answer: That the primary drain is clear and a secondary drain or overflow switch is present
Inspectors verify the primary drain is unobstructed and that a secondary overflow drain or float switch exists to prevent water damage if the primary drain clogs.
Which type of heat pump extracts heat energy from groundwater or the earth rather than outdoor air?
Answer: Geothermal (ground-source) heat pump
Geothermal (ground-source) heat pumps use the stable temperature of the ground or groundwater as a heat source in winter and a heat sink in summer.
What is the standard InterNACHI recommendation when a home inspector cannot fully evaluate a component of the HVAC system?
Answer: Report it as inaccessible or unable to be inspected and recommend further evaluation by a qualified HVAC technician
InterNACHI standards require inspectors to report any system or component that could not be inspected and to recommend specialist evaluation when warranted.