NATE GAS HEATING FURNACE
SPECIALTY CERTIFICATION EXAM
QUESTION AND CORRECT
ANSWERS(VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
DOWNLOAD PDF
1. Which fuel is most commonly used in residential gas furnaces?
A. Propane
B. Oil
C. Natural gas
D. Kerosene
Answer: C
Rationale: Natural gas is the most widely available and commonly used
fuel for residential gas heating furnaces.
2. The primary function of the heat exchanger is to:
A. Transfer refrigerant
B. Burn excess fuel
C. Transfer heat from combustion gases to indoor air
D. Exhaust flue gases
Answer: C
Rationale: The heat exchanger allows heat transfer while keeping
combustion gases separate from indoor air.
3. What device proves flame presence in modern gas furnaces?
A. Thermocouple
B. Flame sensor
C. Limit switch
, D. Gas valve
Answer: B
Rationale: Flame sensors detect flame by measuring microamp current
through ionized flame.
4. A cracked heat exchanger primarily poses which risk?
A. Poor efficiency
B. Noise
C. Carbon monoxide entering living space
D. High gas pressure
Answer: C
Rationale: Cracks can allow combustion gases, including CO, to mix with
supply air.
5. What component controls gas flow to the burners?
A. Draft inducer
B. Gas valve
C. Pressure switch
D. Blower motor
Answer: B
Rationale: The gas valve opens and closes to regulate gas flow to the
burners.
6. The inducer motor’s main purpose is to:
A. Circulate indoor air
B. Establish proper draft before ignition
C. Ignite the burners
D. Control gas pressure
Answer: B
Rationale: The inducer ensures safe venting by creating draft prior to
burner ignition.
7. A pressure switch opens if:
A. Gas pressure is too high
B. Flame is lost
C. Draft is inadequate
D. Temperature rises
, Answer: C
Rationale: Pressure switches verify proper draft conditions for safe
combustion.
8. Which ignition system uses a high-voltage spark?
A. Hot surface ignition
B. Standing pilot
C. Intermittent spark ignition
D. Flame rectification
Answer: C
Rationale: Intermittent spark systems generate a high-voltage spark to
ignite gas.
9. Hot surface igniters are typically made of:
A. Copper
B. Steel
C. Silicon carbide or silicon nitride
D. Aluminum
Answer: C
Rationale: These materials withstand high temperatures and provide
reliable ignition.
10.What does AFUE measure?
A. Combustion temperature
B. Seasonal fuel efficiency
C. Airflow rate
D. Heat exchanger size
Answer: B
Rationale: AFUE represents the percentage of fuel converted to usable
heat over a season.
11.A high-limit switch opens when:
A. Flame is detected
B. Temperature exceeds safe limits
C. Draft fails
D. Gas pressure drops
SPECIALTY CERTIFICATION EXAM
QUESTION AND CORRECT
ANSWERS(VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
DOWNLOAD PDF
1. Which fuel is most commonly used in residential gas furnaces?
A. Propane
B. Oil
C. Natural gas
D. Kerosene
Answer: C
Rationale: Natural gas is the most widely available and commonly used
fuel for residential gas heating furnaces.
2. The primary function of the heat exchanger is to:
A. Transfer refrigerant
B. Burn excess fuel
C. Transfer heat from combustion gases to indoor air
D. Exhaust flue gases
Answer: C
Rationale: The heat exchanger allows heat transfer while keeping
combustion gases separate from indoor air.
3. What device proves flame presence in modern gas furnaces?
A. Thermocouple
B. Flame sensor
C. Limit switch
, D. Gas valve
Answer: B
Rationale: Flame sensors detect flame by measuring microamp current
through ionized flame.
4. A cracked heat exchanger primarily poses which risk?
A. Poor efficiency
B. Noise
C. Carbon monoxide entering living space
D. High gas pressure
Answer: C
Rationale: Cracks can allow combustion gases, including CO, to mix with
supply air.
5. What component controls gas flow to the burners?
A. Draft inducer
B. Gas valve
C. Pressure switch
D. Blower motor
Answer: B
Rationale: The gas valve opens and closes to regulate gas flow to the
burners.
6. The inducer motor’s main purpose is to:
A. Circulate indoor air
B. Establish proper draft before ignition
C. Ignite the burners
D. Control gas pressure
Answer: B
Rationale: The inducer ensures safe venting by creating draft prior to
burner ignition.
7. A pressure switch opens if:
A. Gas pressure is too high
B. Flame is lost
C. Draft is inadequate
D. Temperature rises
, Answer: C
Rationale: Pressure switches verify proper draft conditions for safe
combustion.
8. Which ignition system uses a high-voltage spark?
A. Hot surface ignition
B. Standing pilot
C. Intermittent spark ignition
D. Flame rectification
Answer: C
Rationale: Intermittent spark systems generate a high-voltage spark to
ignite gas.
9. Hot surface igniters are typically made of:
A. Copper
B. Steel
C. Silicon carbide or silicon nitride
D. Aluminum
Answer: C
Rationale: These materials withstand high temperatures and provide
reliable ignition.
10.What does AFUE measure?
A. Combustion temperature
B. Seasonal fuel efficiency
C. Airflow rate
D. Heat exchanger size
Answer: B
Rationale: AFUE represents the percentage of fuel converted to usable
heat over a season.
11.A high-limit switch opens when:
A. Flame is detected
B. Temperature exceeds safe limits
C. Draft fails
D. Gas pressure drops
