CT Gas Heating Contractor Exam
Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas furnace heat exchanger?
A. To regulate gas pressure
B. To circulate combustion air
C. To transfer heat from combustion gases to the air being heated
D. To control the thermostat
Rationale: The heat exchanger separates combustion products from
the conditioned air while transferring heat into the air stream. A
properly functioning heat exchanger is essential for safe furnace
operation because it prevents combustion gases from entering the
occupied space.
, 2. Which gas is commonly used as a fuel for residential gas heating
equipment?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Natural gas
Rationale: Natural gas is widely used in residential and commercial
heating systems. It consists primarily of methane and requires proper
combustion air, ignition, and venting for safe operation.
3. What is the purpose of a furnace flame sensor?
A. To increase gas pressure
B. To measure room temperature
C. To verify that a burner flame has been established
D. To control blower speed
Rationale: A flame sensor confirms that the burner has successfully
ignited. If the control system does not detect flame, it normally shuts
off the gas supply to prevent unburned gas from accumulating.
4. A gas furnace repeatedly starts and stops after operating for only
a few minutes. Which condition is a likely cause?
,A. Oversized return grille
B. Restricted airflow causing the high-limit control to open
C. Low thermostat setting
D. Excessive condensate drainage
Rationale: Restricted airflow can cause the furnace heat exchanger to
become excessively hot. The high-limit safety control then opens to
protect the equipment, causing the burners to shut down.
5. What is the primary function of a thermostat in a gas heating
system?
A. To regulate gas pressure
B. To measure flue-gas temperature
C. To sense space temperature and call for heating when necessary
D. To control combustion-air volume directly
Rationale: The thermostat monitors indoor temperature and signals
the heating equipment when heat is required. The furnace controls
then sequence ignition, gas flow, and blower operation.
6. What component opens and closes to control the flow of gas to a
burner?
A. Draft inducer
B. Heat exchanger
, C. Gas control valve
D. Limit switch
Rationale: The gas control valve regulates fuel flow to the burners.
Depending on the equipment design, it may operate at a single
pressure, two stages, or modulating capacity.
7. What is the purpose of a draft inducer motor on a high-efficiency
gas furnace?
A. To circulate heated air through the building
B. To establish proper combustion airflow and venting through the
heat exchanger and vent system
C. To regulate room humidity
D. To increase gas pressure
Rationale: The draft inducer creates the required pressure differential
for combustion and venting. In many modern furnaces, a pressure
switch verifies proper inducer operation before gas ignition is
permitted.
8. What is carbon monoxide primarily produced by?
A. Complete combustion with excess oxygen
B. Condensation in the vent
Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas furnace heat exchanger?
A. To regulate gas pressure
B. To circulate combustion air
C. To transfer heat from combustion gases to the air being heated
D. To control the thermostat
Rationale: The heat exchanger separates combustion products from
the conditioned air while transferring heat into the air stream. A
properly functioning heat exchanger is essential for safe furnace
operation because it prevents combustion gases from entering the
occupied space.
, 2. Which gas is commonly used as a fuel for residential gas heating
equipment?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Natural gas
Rationale: Natural gas is widely used in residential and commercial
heating systems. It consists primarily of methane and requires proper
combustion air, ignition, and venting for safe operation.
3. What is the purpose of a furnace flame sensor?
A. To increase gas pressure
B. To measure room temperature
C. To verify that a burner flame has been established
D. To control blower speed
Rationale: A flame sensor confirms that the burner has successfully
ignited. If the control system does not detect flame, it normally shuts
off the gas supply to prevent unburned gas from accumulating.
4. A gas furnace repeatedly starts and stops after operating for only
a few minutes. Which condition is a likely cause?
,A. Oversized return grille
B. Restricted airflow causing the high-limit control to open
C. Low thermostat setting
D. Excessive condensate drainage
Rationale: Restricted airflow can cause the furnace heat exchanger to
become excessively hot. The high-limit safety control then opens to
protect the equipment, causing the burners to shut down.
5. What is the primary function of a thermostat in a gas heating
system?
A. To regulate gas pressure
B. To measure flue-gas temperature
C. To sense space temperature and call for heating when necessary
D. To control combustion-air volume directly
Rationale: The thermostat monitors indoor temperature and signals
the heating equipment when heat is required. The furnace controls
then sequence ignition, gas flow, and blower operation.
6. What component opens and closes to control the flow of gas to a
burner?
A. Draft inducer
B. Heat exchanger
, C. Gas control valve
D. Limit switch
Rationale: The gas control valve regulates fuel flow to the burners.
Depending on the equipment design, it may operate at a single
pressure, two stages, or modulating capacity.
7. What is the purpose of a draft inducer motor on a high-efficiency
gas furnace?
A. To circulate heated air through the building
B. To establish proper combustion airflow and venting through the
heat exchanger and vent system
C. To regulate room humidity
D. To increase gas pressure
Rationale: The draft inducer creates the required pressure differential
for combustion and venting. In many modern furnaces, a pressure
switch verifies proper inducer operation before gas ignition is
permitted.
8. What is carbon monoxide primarily produced by?
A. Complete combustion with excess oxygen
B. Condensation in the vent
