InterNACHI - International Association of Certified Home Inspectors HVAC Systems Analysis Questions and Answers

Question 1

While inspecting a central air conditioning system on a warm day, an inspector observes a significant amount of ice on the evaporator coil and the suction line.
Which of the following is the most likely cause of this condition?

Accepted Answer

Restricted airflow across the evaporator coil or a low refrigerant charge.

Answer

The system is oversized for the home.

Answer

The thermostat is set to a very low temperature.

Answer

The outdoor condenser unit is dirty and cannot reject heat effectively.

Question 2

What does the Annual Fuel Utilization Efficiency (AFUE) rating of a furnace represent?

Accepted Answer

The percentage of fuel consumed that is converted into usable heat for the home over a year.

Answer

The speed at which the furnace can heat a space, measured in BTUs per hour.

Answer

The cooling efficiency of the system when paired with an air conditioner.

Answer

The effectiveness of the furnace's air filtration system.

Question 3

Which of the following represents the MOST significant life-safety hazard associated with a cracked heat exchanger in a gas-fired furnace?

Accepted Answer

The potential for combustion gases, like carbon monoxide, to mix with the circulated household air.

Answer

A significant decrease in the furnace's heating efficiency.

Answer

The furnace may overheat and shut down on a safety limit switch.

Answer

Loud banging or popping noises during furnace operation.

Question 4

During an attic inspection, you observe flexible ductwork that is compressed in several areas and has multiple sharp 90-degree bends. What is the primary defect to report?

Accepted Answer

The sharp bends and compression severely restrict airflow, reducing system performance and efficiency.

Answer

The ductwork is not adequately insulated for an attic application.

Answer

The ductwork material is not approved for residential use.

Answer

The flexible ductwork should be replaced with rigid metal ducting.

Question 5

An inspector is examining the refrigerant lines connected to an outdoor condenser unit. One line is larger in diameter, insulated, and feels cool to the touch while the system is operating in cooling mode. This line is known as the:

Accepted Answer

Suction line

Answer

Liquid line

Answer

Discharge line

Answer

Condensate line

Question 6

What is the primary function of a condensate trap on the drain line of an indoor air handler coil?

Accepted Answer

To create a water seal that prevents air from being drawn into or blown out of the unit through the drain.

Answer

To prevent insects and pests from entering the unit through the drain line.

Answer

To measure the amount of water being removed from the air.

Answer

To provide a convenient location for adding cleaning tablets to the system.