Wisconsin Heating Systems Installer Qualification
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
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1. What is the primary purpose of a furnace heat exchanger?
A. Increase gas pressure
B. Circulate combustion gases through the occupied space
C. Transfer heat from combustion gases to the air being heated
D. Reduce electrical voltage
Answer: C. Transfer heat from combustion gases to the air being
heated
Rationale: The heat exchanger transfers thermal energy from the
combustion process to the circulating air without allowing combustion
products to mix with the conditioned air. A properly functioning heat
exchanger is essential for safe and efficient furnace operation.
, 2. Which device is commonly used to prove that a gas-fired furnace
has established proper draft before allowing continued burner
operation?
A. Flame sensor
B. Pressure switch
C. Limit switch
D. Transformer
Answer: B. Pressure switch
Rationale: A furnace pressure switch monitors conditions associated
with the venting and inducer system. It helps verify that the furnace has
established the required pressure or draft conditions before the control
system permits normal burner operation.
3. What is the main function of a furnace limit control?
A. Increase blower speed during cooling
B. Prevent excessive furnace temperature
C. Increase gas pressure
D. Control room humidity
Answer: B. Prevent excessive furnace temperature
Rationale: The high-limit control opens the heating control circuit when
furnace temperature becomes excessive. This protects the heat
,exchanger and other components from overheating and helps reduce
fire and equipment hazards.
4. Which component typically initiates the ignition sequence in a
modern gas furnace?
A. Thermostat
B. Ignition control
C. Blower wheel
D. Return-air grille
Answer: B. Ignition control
Rationale: The ignition control coordinates the startup sequence,
including inducer operation, safety verification, ignition, and gas-valve
operation. The thermostat normally provides the initial call for heat, but
the ignition control manages the furnace's operating sequence.
5. What is the purpose of a flame sensor on a modern gas furnace?
A. Measure return-air temperature
B. Detect whether burner flame has been established
C. Measure gas pressure continuously
D. Control blower lubrication
Answer: B. Detect whether burner flame has been established
, Rationale: The flame sensor provides the control board with
confirmation that a burner flame exists. If the expected flame signal is
not detected, the control system generally shuts off the gas supply as a
safety measure.
6. A thermostat calls for heat, but the furnace blower operates
without burner ignition. Which condition could cause this
symptom?
A. Open safety circuit
B. Oversized return grille
C. Dirty thermostat cover
D. Excessive room lighting
Answer: A. Open safety circuit
Rationale: Modern furnaces contain multiple safety controls that must
be satisfied before the gas valve can operate. An open limit, pressure
switch, rollout control, or another safety device can interrupt the
ignition sequence while the blower may continue operating.
7. What is the primary purpose of an induced-draft motor in a
modern gas furnace?
A. Circulate conditioned air through the building
B. Move combustion air and combustion products through the furnace
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of a furnace heat exchanger?
A. Increase gas pressure
B. Circulate combustion gases through the occupied space
C. Transfer heat from combustion gases to the air being heated
D. Reduce electrical voltage
Answer: C. Transfer heat from combustion gases to the air being
heated
Rationale: The heat exchanger transfers thermal energy from the
combustion process to the circulating air without allowing combustion
products to mix with the conditioned air. A properly functioning heat
exchanger is essential for safe and efficient furnace operation.
, 2. Which device is commonly used to prove that a gas-fired furnace
has established proper draft before allowing continued burner
operation?
A. Flame sensor
B. Pressure switch
C. Limit switch
D. Transformer
Answer: B. Pressure switch
Rationale: A furnace pressure switch monitors conditions associated
with the venting and inducer system. It helps verify that the furnace has
established the required pressure or draft conditions before the control
system permits normal burner operation.
3. What is the main function of a furnace limit control?
A. Increase blower speed during cooling
B. Prevent excessive furnace temperature
C. Increase gas pressure
D. Control room humidity
Answer: B. Prevent excessive furnace temperature
Rationale: The high-limit control opens the heating control circuit when
furnace temperature becomes excessive. This protects the heat
,exchanger and other components from overheating and helps reduce
fire and equipment hazards.
4. Which component typically initiates the ignition sequence in a
modern gas furnace?
A. Thermostat
B. Ignition control
C. Blower wheel
D. Return-air grille
Answer: B. Ignition control
Rationale: The ignition control coordinates the startup sequence,
including inducer operation, safety verification, ignition, and gas-valve
operation. The thermostat normally provides the initial call for heat, but
the ignition control manages the furnace's operating sequence.
5. What is the purpose of a flame sensor on a modern gas furnace?
A. Measure return-air temperature
B. Detect whether burner flame has been established
C. Measure gas pressure continuously
D. Control blower lubrication
Answer: B. Detect whether burner flame has been established
, Rationale: The flame sensor provides the control board with
confirmation that a burner flame exists. If the expected flame signal is
not detected, the control system generally shuts off the gas supply as a
safety measure.
6. A thermostat calls for heat, but the furnace blower operates
without burner ignition. Which condition could cause this
symptom?
A. Open safety circuit
B. Oversized return grille
C. Dirty thermostat cover
D. Excessive room lighting
Answer: A. Open safety circuit
Rationale: Modern furnaces contain multiple safety controls that must
be satisfied before the gas valve can operate. An open limit, pressure
switch, rollout control, or another safety device can interrupt the
ignition sequence while the blower may continue operating.
7. What is the primary purpose of an induced-draft motor in a
modern gas furnace?
A. Circulate conditioned air through the building
B. Move combustion air and combustion products through the furnace
