CFESA Gas Certification Exam 2026/2027
| 300+ Practice Questions, Correct
Answers & Detailed Rationales
1. What three elements are required for normal combustion?
A. Fuel, oxygen and ignition energy
B. Water, fuel and refrigerant
C. Steam, oxygen and oil
D. Electricity, water and nitrogen
Correct Answer: A
Rationale: Combustion requires a fuel source, an oxidizer such as oxygen, and sufficient ignition
energy to initiate the combustion process.
2. What is the primary purpose of a gas safety valve?
A. Increase gas pressure indefinitely
B. Control or shut off gas flow when required
C. Increase combustion-air volume
D. Measure burner temperature
Correct Answer: B
Rationale: A gas safety valve controls gas delivery and is designed to shut off the gas supply
under specified unsafe or abnormal conditions.
3. Why is adequate combustion air important?
A. It supports proper combustion
B. It eliminates the need for fuel
C. It lowers electrical resistance
D. It increases refrigerant flow
Correct Answer: A
,Rationale: Gas appliances require sufficient combustion air to burn fuel properly. Inadequate air
can result in incomplete or unstable combustion.
4. What can insufficient combustion air cause?
A. Poor or incomplete combustion
B. Guaranteed higher efficiency
C. Increased electrical frequency
D. Lower water hardness
Correct Answer: A
Rationale: Insufficient combustion air can prevent the fuel-air mixture from burning properly
and may produce undesirable combustion products.
5. What is the function of a gas regulator?
A. Control gas pressure
B. Control refrigeration superheat
C. Measure electrical current
D. Remove condensate
Correct Answer: A
Rationale: A gas regulator maintains gas pressure within an appropriate range for the appliance.
6. Which instrument is appropriate for measuring gas pressure?
A. Manometer
B. Ohmmeter
C. Megohmmeter
D. Thermocouple only
Correct Answer: A
Rationale: A manometer or appropriate digital pressure instrument can be used to measure gas
pressure, depending on the equipment and required measurement range.
7. Before servicing a gas appliance, the technician should:
,A. Increase gas pressure
B. Follow the required gas shutoff and safety procedures
C. Bypass the safety valve
D. Remove the burner
Correct Answer: B
Rationale: Gas service must begin with proper isolation and safety procedures to control the
fuel source and prevent accidental release or ignition.
8. What is the primary purpose of a burner?
A. Mix and burn fuel with combustion air
B. Compress refrigerant
C. Store condensate
D. Regulate electrical voltage
Correct Answer: A
Rationale: The burner provides controlled combustion by delivering and mixing fuel and air in
an appropriate manner.
9. What does a thermostat normally sense?
A. Temperature
B. Gas pipe diameter
C. Electrical resistance only
D. Refrigerant charge
Correct Answer: A
Rationale: A thermostat responds to temperature and uses that information to control
equipment operation.
10. A gas appliance repeatedly fails to ignite. Which system should be investigated?
A. Ignition and gas-control sequence
B. Evaporator drain
C. Refrigerant receiver only
D. Steam trap only
, Correct Answer: A
Rationale: Ignition failure can result from problems with ignition, gas delivery, flame sensing or
the control sequence.
11. Why is a flame-sensing system used on many gas appliances?
A. To verify that ignition/flame has been established
B. To increase gas pressure
C. To measure water hardness
D. To control compressor speed
Correct Answer: A
Rationale: Flame sensing allows the control system to determine whether a safe flame
condition exists before continuing gas operation.
12. What should happen if a gas safety control detects an unsafe flame condition?
A. Gas flow should be safely interrupted according to the control system
B. Gas flow should automatically increase
C. The burner should receive more fuel
D. The thermostat should be bypassed
Correct Answer: A
Rationale: The safety system is intended to prevent continued uncontrolled gas flow when the
required flame condition is not established.
13. Why should a gas safety device never be casually bypassed?
A. It can defeat a protective function
B. It increases water quality
C. It lowers electrical current
D. It improves combustion automatically
Correct Answer: A
Rationale: Safety controls exist to protect against hazardous operating conditions. Bypassing
them can expose people and equipment to serious hazards.
| 300+ Practice Questions, Correct
Answers & Detailed Rationales
1. What three elements are required for normal combustion?
A. Fuel, oxygen and ignition energy
B. Water, fuel and refrigerant
C. Steam, oxygen and oil
D. Electricity, water and nitrogen
Correct Answer: A
Rationale: Combustion requires a fuel source, an oxidizer such as oxygen, and sufficient ignition
energy to initiate the combustion process.
2. What is the primary purpose of a gas safety valve?
A. Increase gas pressure indefinitely
B. Control or shut off gas flow when required
C. Increase combustion-air volume
D. Measure burner temperature
Correct Answer: B
Rationale: A gas safety valve controls gas delivery and is designed to shut off the gas supply
under specified unsafe or abnormal conditions.
3. Why is adequate combustion air important?
A. It supports proper combustion
B. It eliminates the need for fuel
C. It lowers electrical resistance
D. It increases refrigerant flow
Correct Answer: A
,Rationale: Gas appliances require sufficient combustion air to burn fuel properly. Inadequate air
can result in incomplete or unstable combustion.
4. What can insufficient combustion air cause?
A. Poor or incomplete combustion
B. Guaranteed higher efficiency
C. Increased electrical frequency
D. Lower water hardness
Correct Answer: A
Rationale: Insufficient combustion air can prevent the fuel-air mixture from burning properly
and may produce undesirable combustion products.
5. What is the function of a gas regulator?
A. Control gas pressure
B. Control refrigeration superheat
C. Measure electrical current
D. Remove condensate
Correct Answer: A
Rationale: A gas regulator maintains gas pressure within an appropriate range for the appliance.
6. Which instrument is appropriate for measuring gas pressure?
A. Manometer
B. Ohmmeter
C. Megohmmeter
D. Thermocouple only
Correct Answer: A
Rationale: A manometer or appropriate digital pressure instrument can be used to measure gas
pressure, depending on the equipment and required measurement range.
7. Before servicing a gas appliance, the technician should:
,A. Increase gas pressure
B. Follow the required gas shutoff and safety procedures
C. Bypass the safety valve
D. Remove the burner
Correct Answer: B
Rationale: Gas service must begin with proper isolation and safety procedures to control the
fuel source and prevent accidental release or ignition.
8. What is the primary purpose of a burner?
A. Mix and burn fuel with combustion air
B. Compress refrigerant
C. Store condensate
D. Regulate electrical voltage
Correct Answer: A
Rationale: The burner provides controlled combustion by delivering and mixing fuel and air in
an appropriate manner.
9. What does a thermostat normally sense?
A. Temperature
B. Gas pipe diameter
C. Electrical resistance only
D. Refrigerant charge
Correct Answer: A
Rationale: A thermostat responds to temperature and uses that information to control
equipment operation.
10. A gas appliance repeatedly fails to ignite. Which system should be investigated?
A. Ignition and gas-control sequence
B. Evaporator drain
C. Refrigerant receiver only
D. Steam trap only
, Correct Answer: A
Rationale: Ignition failure can result from problems with ignition, gas delivery, flame sensing or
the control sequence.
11. Why is a flame-sensing system used on many gas appliances?
A. To verify that ignition/flame has been established
B. To increase gas pressure
C. To measure water hardness
D. To control compressor speed
Correct Answer: A
Rationale: Flame sensing allows the control system to determine whether a safe flame
condition exists before continuing gas operation.
12. What should happen if a gas safety control detects an unsafe flame condition?
A. Gas flow should be safely interrupted according to the control system
B. Gas flow should automatically increase
C. The burner should receive more fuel
D. The thermostat should be bypassed
Correct Answer: A
Rationale: The safety system is intended to prevent continued uncontrolled gas flow when the
required flame condition is not established.
13. Why should a gas safety device never be casually bypassed?
A. It can defeat a protective function
B. It increases water quality
C. It lowers electrical current
D. It improves combustion automatically
Correct Answer: A
Rationale: Safety controls exist to protect against hazardous operating conditions. Bypassing
them can expose people and equipment to serious hazards.
