FC FC Heat Exchangers & Blower Systems 2

Question 1

What is AFUE and what does a rating of 96% mean for a furnace?

Accepted Answer

Annual Fuel Utilization Efficiency; 96% of fuel energy is converted to usable heat

Answer

AFUE (Annual Fuel Utilization Efficiency) measures seasonal heating efficiency; 96% AFUE means 96 cents of every dollar of fuel is converted to heat.

Question 2

What is the purpose of lubricating PSC blower motor bearings annually?

Accepted Answer

To reduce friction, prevent overheating, and extend motor bearing life

Answer

Lubricating sleeve or ball bearings in PSC motors reduces friction heat, prevents premature wear, and extends motor service life.

Question 3

What is the consequence of running a furnace blower with an unbalanced or dirty squirrel cage wheel?

Accepted Answer

Vibration, noise, reduced airflow, and premature motor and bearing failure

Answer

Dirt buildup on blower wheel blades causes imbalance, vibration, and airflow reduction that stresses the motor shaft and bearings.

Question 4

When measuring blower motor amperage, a reading above the nameplate FLA (Full Load Amps) indicates which condition?

Accepted Answer

The motor is overloaded due to restricted airflow or a failing motor

Answer

Current draw above nameplate FLA indicates the motor is working harder than designed, typically from restricted airflow or internal motor problems, risking overheating.

Question 5

What is the function of the blower delay-off control at the end of a heating cycle?

Accepted Answer

To keep the blower running after the burner shuts off to recover residual heat from the heat exchanger

Answer

The blower continues running for 1–3 minutes after burner shutdown to extract residual heat stored in the heat exchanger and deliver it to the living space.

(FC) Furnace Installation and Maintenance Certification Practice Test

(FC) Furnace Installation and Maintenance Certification Practice Test

FC FC Heat Exchangers & Blower Systems 2