CT Gas Heating Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas pressure regulator in a gas heating
system?
A. To increase gas pressure
B. To maintain a constant gas pressure **
C. To shut off gas automatically
D. To filter impurities in gas
Answer: B
Rationale: A gas pressure regulator maintains a constant outlet
pressure to ensure safe and efficient operation of the heating
appliance.
2. The minimum clearance from a gas furnace to combustible materials is
typically:
A. 1 inch
B. 6 inches **
C. 12 inches
D. 24 inches
Answer: B
Rationale: Manufacturers and code requirements usually specify a
minimum clearance of 6 inches to prevent fire hazards.
3. Which type of gas is commonly used in residential heating?
A. Propane **
B. Hydrogen
C. Carbon monoxide
D. Methanol
Answer: A
, Rationale: Propane and natural gas are the most common fuels for
residential heating systems.
4. What is the main function of a draft inducer in a gas furnace?
A. To mix air and fuel
B. To remove combustion gases from the heat exchanger **
C. To regulate gas pressure
D. To ignite the burner
Answer: B
Rationale: The draft inducer ensures that combustion gases are
safely expelled through the venting system.
5. When performing a combustion analysis, the CO2 level in a properly
adjusted gas furnace should be approximately:
A. 5–8%
B. 8–10% **
C. 10–12%
D. 12–15%
Answer: B
Rationale: Proper combustion in a gas furnace typically results in
CO2 levels between 8–10%, indicating efficient fuel use.
6. Which component prevents backflow of gas in a gas heating system?
A. Thermostat
B. Gas valve
C. Check valve **
D. Pilot light
Answer: C
Rationale: A check valve allows gas flow in only one direction,
preventing backflow that could cause unsafe conditions.
7. The ignition system in a modern gas furnace is usually:
A. Standing pilot
B. Intermittent pilot **
C. Manual spark
D. Natural flame only
Answer: B
Rationale: Intermittent pilot or electronic ignition systems reduce gas
usage and improve safety compared to standing pilots.
8. In a gas heating system, what is the purpose of the limit switch?
A. Control gas pressure
, B. Shut off furnace if it overheats **
C. Maintain combustion efficiency
D. Detect CO levels
Answer: B
Rationale: The limit switch protects the furnace from overheating by
turning off the burners when the temperature exceeds safe limits.
9. The venting material for a high-efficiency condensing furnace is
typically:
A. Steel **
B. PVC or CPVC **
C. Aluminum
D. Copper
Answer: B
Rationale: High-efficiency furnaces produce condensate that can
corrode metal vents, so PVC or CPVC is used for resistance to
corrosion.
10. What is the purpose of a thermocouple in a gas furnace?
A. Measure temperature
B. Detect flame presence **
C. Regulate airflow
D. Increase combustion efficiency
Answer: B
Rationale: A thermocouple senses the presence of a flame and signals
the gas valve to stay open, preventing gas leakage.
11. When sizing a gas line, what is the primary factor to consider?
A. Pipe color
B. Length and BTU demand **
C. Ambient temperature
D. Type of insulation
Answer: B
Rationale: Pipe sizing depends on the length of the run and the total
BTU demand of the appliances to ensure adequate pressure and flow.
12. Which gas appliance requires a 3-wire electrical connection?
A. Millivolt gas furnace
B. 120V induced draft furnace **
C. Standing pilot water heater
D. Vent-free space heater
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas pressure regulator in a gas heating
system?
A. To increase gas pressure
B. To maintain a constant gas pressure **
C. To shut off gas automatically
D. To filter impurities in gas
Answer: B
Rationale: A gas pressure regulator maintains a constant outlet
pressure to ensure safe and efficient operation of the heating
appliance.
2. The minimum clearance from a gas furnace to combustible materials is
typically:
A. 1 inch
B. 6 inches **
C. 12 inches
D. 24 inches
Answer: B
Rationale: Manufacturers and code requirements usually specify a
minimum clearance of 6 inches to prevent fire hazards.
3. Which type of gas is commonly used in residential heating?
A. Propane **
B. Hydrogen
C. Carbon monoxide
D. Methanol
Answer: A
, Rationale: Propane and natural gas are the most common fuels for
residential heating systems.
4. What is the main function of a draft inducer in a gas furnace?
A. To mix air and fuel
B. To remove combustion gases from the heat exchanger **
C. To regulate gas pressure
D. To ignite the burner
Answer: B
Rationale: The draft inducer ensures that combustion gases are
safely expelled through the venting system.
5. When performing a combustion analysis, the CO2 level in a properly
adjusted gas furnace should be approximately:
A. 5–8%
B. 8–10% **
C. 10–12%
D. 12–15%
Answer: B
Rationale: Proper combustion in a gas furnace typically results in
CO2 levels between 8–10%, indicating efficient fuel use.
6. Which component prevents backflow of gas in a gas heating system?
A. Thermostat
B. Gas valve
C. Check valve **
D. Pilot light
Answer: C
Rationale: A check valve allows gas flow in only one direction,
preventing backflow that could cause unsafe conditions.
7. The ignition system in a modern gas furnace is usually:
A. Standing pilot
B. Intermittent pilot **
C. Manual spark
D. Natural flame only
Answer: B
Rationale: Intermittent pilot or electronic ignition systems reduce gas
usage and improve safety compared to standing pilots.
8. In a gas heating system, what is the purpose of the limit switch?
A. Control gas pressure
, B. Shut off furnace if it overheats **
C. Maintain combustion efficiency
D. Detect CO levels
Answer: B
Rationale: The limit switch protects the furnace from overheating by
turning off the burners when the temperature exceeds safe limits.
9. The venting material for a high-efficiency condensing furnace is
typically:
A. Steel **
B. PVC or CPVC **
C. Aluminum
D. Copper
Answer: B
Rationale: High-efficiency furnaces produce condensate that can
corrode metal vents, so PVC or CPVC is used for resistance to
corrosion.
10. What is the purpose of a thermocouple in a gas furnace?
A. Measure temperature
B. Detect flame presence **
C. Regulate airflow
D. Increase combustion efficiency
Answer: B
Rationale: A thermocouple senses the presence of a flame and signals
the gas valve to stay open, preventing gas leakage.
11. When sizing a gas line, what is the primary factor to consider?
A. Pipe color
B. Length and BTU demand **
C. Ambient temperature
D. Type of insulation
Answer: B
Rationale: Pipe sizing depends on the length of the run and the total
BTU demand of the appliances to ensure adequate pressure and flow.
12. Which gas appliance requires a 3-wire electrical connection?
A. Millivolt gas furnace
B. 120V induced draft furnace **
C. Standing pilot water heater
D. Vent-free space heater
