Red Seal Gasfitter Class A Exam Questions with Answers

Red Seal Gasfitter Class A Exam Questions WITH
CORRECT ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A |INSTANT DOWNLOAD
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1. Which type of gas is commonly used for domestic heating in
Canada?
A. Propane
B. Natural Gas
C. Butane
D. Hydrogen
Correct Answer: B. Natural Gas
Rationale: Natural gas is the primary gas used in domestic
heating due to availability, safety, and cost-effectiveness.
2. What is the purpose of a gas regulator?
A. To increase gas pressure
B. To decrease and stabilize gas pressure
C. To filter impurities
D. To ignite gas appliances
Correct Answer: B. To decrease and stabilize gas pressure
Rationale: Gas regulators control and maintain a constant
outlet pressure, ensuring safe operation of appliances.
3. When installing a gas line, what is the maximum allowable
leak rate for testing?
A. 0.1 psi/min
B. 0.25 psi/min

,C. 0.5 psi/min
D. 1 psi/min
Correct Answer: B. 0.25 psi/min
Rationale: Pressure testing standards require a maximum
allowable leak rate of 0.25 psi/min to ensure the system is leak-
free.
4. Which material is commonly used for underground natural
gas piping?
A. Copper
B. Polyethylene (PE)
C. PVC
D. Steel
Correct Answer: B. Polyethylene (PE)
Rationale: PE piping is corrosion-resistant, flexible, and
approved for buried natural gas lines.
5. What is the minimum clearance required between a gas
appliance vent and combustible material?
A. 1 inch
B. 2 inches
C. 6 inches
D. 12 inches
Correct Answer: C. 6 inches
Rationale: Building codes specify at least 6 inches clearance
from combustibles to prevent fire hazards.
6. What is the function of a thermocouple in a gas appliance?
A. To measure gas flow

,B. To ignite gas
C. To detect flame and shut off gas if flame fails
D. To regulate gas pressure
Correct Answer: C. To detect flame and shut off gas if flame fails
Rationale: The thermocouple generates a voltage when heated
by the flame; if the flame goes out, it closes the gas valve to
prevent leaks.
7. Which type of venting is suitable for high-efficiency gas
furnaces?
A. Single-wall metal vent
B. B-Vent
C. PVC vent
D. Chimney liner
Correct Answer: C. PVC vent
Rationale: High-efficiency furnaces produce cooler exhaust
gases, making PVC suitable for venting.
8. How often should a gas appliance be inspected for safety?
A. Monthly
B. Annually
C. Every 5 years
D. Only when malfunctioning
Correct Answer: B. Annually
Rationale: Annual inspections ensure appliance safety,
efficiency, and compliance with regulations.
9. What is the maximum allowable working pressure for a
Class A gas system?

, A. 1 psi
B. 2 psi
C. 5 psi
D. 10 psi
Correct Answer: A. 1 psi
Rationale: Class A systems are low-pressure systems; exceeding
1 psi can be unsafe and is non-compliant.
10. What is the correct procedure for purging air from a new
gas line?
A. Open all appliances at once
B. Use nitrogen to push air out before introducing gas
C. Start the furnace immediately
D. Allow air to vent naturally over time
Correct Answer: B. Use nitrogen to push air out before
introducing gas
Rationale: Purging with an inert gas like nitrogen prevents
flammable air-gas mixtures and ensures safety.
11. Which tool is essential for checking gas leaks in a system?
A. Manometer
B. Pressure gauge
C. Soap solution or electronic gas detector
D. Voltmeter
Correct Answer: C. Soap solution or electronic gas detector
Rationale: Leaks are identified by bubbles in soap solution or by
a sensor detecting escaping gas.