InterNACHI HVAC Systems Analysis 4

Question 1

What does AFUE measure in heating equipment?

Accepted Answer

Annual fuel utilization efficiency

Answer

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.

Question 2

Which venting category applies to high-efficiency condensing furnaces with AFUE ≥90%?

Accepted Answer

Category IV (positive pressure, condensing)

Answer

Category IV applies to positive-pressure, condensing appliances like high-efficiency furnaces, which vent with PVC or CPVC pipe and produce acidic condensate.

Question 3

An inspector observes ice forming on the evaporator coil of a central AC system. Which condition is NOT a likely cause?

Accepted Answer

Oversized ductwork

Answer

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.

Question 4

What is the function of a humidistat in an HVAC system?

Accepted Answer

It activates or deactivates the humidifier based on indoor relative humidity

Answer

A humidistat senses indoor relative humidity and signals the whole-house humidifier to operate when humidity falls below the set point.

Question 5

During an HVAC inspection, what does a home inspector typically verify about the condensate drain system?

Accepted Answer

That the primary drain is clear and a secondary drain or overflow switch is present

Answer

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.

(InterNACHI) International Association of Certified Home Inspectors Practice Test

(InterNACHI) International Association of Certified Home Inspectors Practice Test

InterNACHI HVAC Systems Analysis 4