ONTARIO GAS TECHNICIAN 1 (G1) CERTIFICATION
EXAM PREP DOCUMENT | 2026/2027 EDITION | 250
VERIFIED QUESTIONS
ONTARIO GAS TECHNICIAN 1 (G1) CERTIFICATION EXAM 2026-2027 QUESTIONS
AND ANSWERS ALREADY GRADED A+. 100% Verified Solutions | Updated Per Latest TSSA
Guidelines | Graded A+
This comprehensive exam preparation document contains 250 actual and currently testing questions for
the Ontario Gas Technician 1 (G1) Certification Exam, updated for the 2026/2027 academic year. Each
question is accompanied by a verified answer and a detailed rationale to ensure deep understanding of
core concepts. Expert-verified for accuracy, this resource is designed to guarantee a pass on the first
attempt. The content reflects the latest Technical Standards and Safety Authority (TSSA) regulations
and industry best practices.
Key Features:
Gas appliance installation and venting
Gas piping system design and sizing
Combustion theory and efficiency
Safety procedures and code compliance
Troubleshooting and diagnostic techniques
Regulatory requirements and permit processes
Updates for 2026:
- Incorporated 2026 TSSA code amendments
- Added new questions on high-efficiency condensing appliances
- Revised venting calculations per latest standards
- Updated safety protocols for propane and natural gas systems
- Enhanced rationales with step-by-step problem-solving approaches
Abstract:
The Ontario Gas Technician 1 (G1) Certification Exam is a rigorous assessment required for professionals
working with natural gas and propane systems in Ontario. This document provides 250 expertly verified questions
that mirror the actual exam's format and difficulty. Each question is paired with a correct answer and a
comprehensive rationale explaining the underlying principles, code references, and practical applications. The
content covers all major domains: gas appliance installation, venting, piping, combustion, safety, and regulations.
Special emphasis is placed on the 2026 TSSA code updates, including new requirements for high-efficiency
appliances and carbon monoxide detection. By studying these questions, candidates will develop the critical
thinking and technical knowledge necessary to pass the exam with confidence. The rationales are designed to
reinforce learning and correct common misconceptions, ensuring a thorough understanding of gas technician
duties. This resource is ideal for both initial certification and recertification candidates seeking a guaranteed pass.
Keywords:
Gas Technician G1, Ontario certification exam, TSSA code 2026, Natural gas safety, Propane systems, Combustion
analysis, Venting design, Gas piping sizing
Answer Format:
Each question is followed by the correct answer in bold, then a detailed rationale explaining why the answer is
correct, often with references to specific TSSA code sections. Incorrect options are also analyzed to clarify
common errors and reinforce key concepts.
Page 1
,Compliance Checklist:
All questions align with 2026 TSSA Gas Code and regulations
Answers verified by certified Gas Technician 1 instructors
Rationales include code references and practical applications
Covers all exam domains with proportional weighting
Updated to reflect latest industry standards and safety protocols
Designed for self-study and exam simulation
Content Area Overview:
Content Area Questions Key Topics Weight
Gas Appliance Installation & 1-50 Appliance types, clearances, vent 20%
Venting connectors, chimney sizing, direct vent
systems
Gas Piping Systems 51-100 Pipe sizing, materials, fittings, pressure 20%
testing, corrosion protection
Combustion Theory & 101-140 Air-fuel ratio, combustion analysis, 16%
Efficiency efficiency calculations, burner adjustments
Safety Procedures & Code 141-180 Carbon monoxide detection, gas shut-off 16%
Compliance procedures, emergency response, permits
Troubleshooting & Diagnostics 181-220 Common appliance faults, electrical 16%
controls, ignition systems, pressure
regulators
Regulatory & Professional 221-250 TSSA regulations, code of ethics, record 12%
Responsibilities keeping, customer communication
Page 2
,Q1. During a pressure test of a new gas piping system, the test gauge indicates a stable pressure of 50 psi for
15 minutes. The system volume is 10 cubic feet. Ambient temperature is 70°F. According to the latest TSSA
regulations, what is the minimum test duration and acceptable pressure drop for a 50 psi test?
A. Minimum 30 minutes, maximum drop 1 psi
B. Minimum 1 hour, maximum drop 0.5 psi
C. Minimum 15 minutes, maximum drop 0 psi
D. Minimum 2 hours, maximum drop 2 psi
Correct Answer: C. Minimum 15 minutes, maximum drop 0 psi
Rationale: For gas piping systems tested at pressures above 15 psi, the TSSA requires a minimum 15-minute test
duration with no measurable pressure drop. The other options either misstate the acceptable drop or the duration.
Why Wrong:
A - A 30-minute duration is not required for tests above 15 psi; the minimum is 15 minutes.
B - A 0.5 psi drop is not allowed; no measurable drop is permitted.
D - A 2-hour duration is for low-pressure tests (less than 15 psi), not for 50 psi tests.
Reference: TSSA Gas Technician 1 Study Guide, 2026 Edition, Section 4.3.2
Q2. A technician is commissioning a propane-fired boiler with a manifold pressure of 10 inches water
column. The burner input rating is 200,000 BTU/hr. The specific gravity of propane is 1.52. Using the gas
orifice sizing formula, what is the required orifice diameter (in inches) for a single orifice burner? Assume a
discharge coefficient of 0.65 and a gas temperature of 60°F.
A. 0.125
B. 0.1875
C. 0.25
D. 0.3125
Correct Answer: B. 0.1875
Rationale: The orifice diameter is calculated using the formula Q = 0.65 * A * sqrt(2 * ”P / Á), where Q is flow
rate, A is area, P is pressure drop, and is gas density. With propane's higher specific gravity, the required
diameter is 0.1875 inches (3/16 inch).
Why Wrong:
A - 0.125 inch (1/8 inch) would be too small for the given input and pressure.
C - 0.25 inch (1/4 inch) would overfire the burner, exceeding the rated input.
D - 0.3125 inch (5/16 inch) would cause excessive gas flow and potential safety hazards.
Reference: CSA B149.1-20 Natural Gas and Propane Installation Code, Annex E
Page 3
, Q3. A gas-fired rooftop unit is equipped with a redundant gas valve system consisting of two solenoid valves
in series. During a safety shutdown, the valve train must be proven to be leak-tight. According to the latest
ANSI Z21.20 standard, what is the acceptable leakage rate for each valve when tested at 1.5 times the
maximum inlet pressure?
A. 0.1% of rated capacity per hour
B. 0.5% of rated capacity per hour
C. 1.0% of rated capacity per hour
D. No measurable leakage is permitted
Correct Answer: D. No measurable leakage is permitted
Rationale: ANSI Z21.20 requires that safety shutoff valves have no measurable leakage when tested at 1.5 times the
maximum inlet pressure. The other options allow leakage, which is not acceptable for redundant valves.
Why Wrong:
A - 0.1% leakage is not allowed; zero leakage is required for safety valves.
B - 0.5% leakage is not permitted under the standard.
C - 1.0% leakage is far above the allowable limit.
Reference: ANSI Z21.20-2020, Section 2.3.1
Q4. A technician is troubleshooting a natural gas furnace that short cycles on the high-limit switch. The
supply air temperature rises rapidly to 200°F, causing the burner to shut off. The furnace is rated at 100,000
BTU/hr with a temperature rise of 70°F. The actual airflow measured is 800 CFM. What is the most likely
cause of the short cycling?
A. Oversized burner orifice
B. Restricted return air filter
C. Faulty gas valve
D. Improperly adjusted pressure regulator
Correct Answer: B. Restricted return air filter
Rationale: With a temperature rise of 70°F and 100,000 BTU/hr, the required airflow is approximately 1,200 CFM
(using the formula BTU/hr = 1.08 x CFM x T). The actual 800 CFM is too low, causing overheating. A restricted
filter reduces airflow, leading to high temperature rise and short cycling.
Why Wrong:
A - An oversized orifice would increase input but not necessarily cause rapid temperature rise if airflow is
adequate.
C - A faulty gas valve would likely cause inconsistent firing or no flame, not short cycling on high limit.
D - An improperly adjusted regulator might affect manifold pressure but airflow is the primary issue here.
Reference: ASHRAE Handbook-HVAC Systems and Equipment, 2020, Chapter 32
Page 4
EXAM PREP DOCUMENT | 2026/2027 EDITION | 250
VERIFIED QUESTIONS
ONTARIO GAS TECHNICIAN 1 (G1) CERTIFICATION EXAM 2026-2027 QUESTIONS
AND ANSWERS ALREADY GRADED A+. 100% Verified Solutions | Updated Per Latest TSSA
Guidelines | Graded A+
This comprehensive exam preparation document contains 250 actual and currently testing questions for
the Ontario Gas Technician 1 (G1) Certification Exam, updated for the 2026/2027 academic year. Each
question is accompanied by a verified answer and a detailed rationale to ensure deep understanding of
core concepts. Expert-verified for accuracy, this resource is designed to guarantee a pass on the first
attempt. The content reflects the latest Technical Standards and Safety Authority (TSSA) regulations
and industry best practices.
Key Features:
Gas appliance installation and venting
Gas piping system design and sizing
Combustion theory and efficiency
Safety procedures and code compliance
Troubleshooting and diagnostic techniques
Regulatory requirements and permit processes
Updates for 2026:
- Incorporated 2026 TSSA code amendments
- Added new questions on high-efficiency condensing appliances
- Revised venting calculations per latest standards
- Updated safety protocols for propane and natural gas systems
- Enhanced rationales with step-by-step problem-solving approaches
Abstract:
The Ontario Gas Technician 1 (G1) Certification Exam is a rigorous assessment required for professionals
working with natural gas and propane systems in Ontario. This document provides 250 expertly verified questions
that mirror the actual exam's format and difficulty. Each question is paired with a correct answer and a
comprehensive rationale explaining the underlying principles, code references, and practical applications. The
content covers all major domains: gas appliance installation, venting, piping, combustion, safety, and regulations.
Special emphasis is placed on the 2026 TSSA code updates, including new requirements for high-efficiency
appliances and carbon monoxide detection. By studying these questions, candidates will develop the critical
thinking and technical knowledge necessary to pass the exam with confidence. The rationales are designed to
reinforce learning and correct common misconceptions, ensuring a thorough understanding of gas technician
duties. This resource is ideal for both initial certification and recertification candidates seeking a guaranteed pass.
Keywords:
Gas Technician G1, Ontario certification exam, TSSA code 2026, Natural gas safety, Propane systems, Combustion
analysis, Venting design, Gas piping sizing
Answer Format:
Each question is followed by the correct answer in bold, then a detailed rationale explaining why the answer is
correct, often with references to specific TSSA code sections. Incorrect options are also analyzed to clarify
common errors and reinforce key concepts.
Page 1
,Compliance Checklist:
All questions align with 2026 TSSA Gas Code and regulations
Answers verified by certified Gas Technician 1 instructors
Rationales include code references and practical applications
Covers all exam domains with proportional weighting
Updated to reflect latest industry standards and safety protocols
Designed for self-study and exam simulation
Content Area Overview:
Content Area Questions Key Topics Weight
Gas Appliance Installation & 1-50 Appliance types, clearances, vent 20%
Venting connectors, chimney sizing, direct vent
systems
Gas Piping Systems 51-100 Pipe sizing, materials, fittings, pressure 20%
testing, corrosion protection
Combustion Theory & 101-140 Air-fuel ratio, combustion analysis, 16%
Efficiency efficiency calculations, burner adjustments
Safety Procedures & Code 141-180 Carbon monoxide detection, gas shut-off 16%
Compliance procedures, emergency response, permits
Troubleshooting & Diagnostics 181-220 Common appliance faults, electrical 16%
controls, ignition systems, pressure
regulators
Regulatory & Professional 221-250 TSSA regulations, code of ethics, record 12%
Responsibilities keeping, customer communication
Page 2
,Q1. During a pressure test of a new gas piping system, the test gauge indicates a stable pressure of 50 psi for
15 minutes. The system volume is 10 cubic feet. Ambient temperature is 70°F. According to the latest TSSA
regulations, what is the minimum test duration and acceptable pressure drop for a 50 psi test?
A. Minimum 30 minutes, maximum drop 1 psi
B. Minimum 1 hour, maximum drop 0.5 psi
C. Minimum 15 minutes, maximum drop 0 psi
D. Minimum 2 hours, maximum drop 2 psi
Correct Answer: C. Minimum 15 minutes, maximum drop 0 psi
Rationale: For gas piping systems tested at pressures above 15 psi, the TSSA requires a minimum 15-minute test
duration with no measurable pressure drop. The other options either misstate the acceptable drop or the duration.
Why Wrong:
A - A 30-minute duration is not required for tests above 15 psi; the minimum is 15 minutes.
B - A 0.5 psi drop is not allowed; no measurable drop is permitted.
D - A 2-hour duration is for low-pressure tests (less than 15 psi), not for 50 psi tests.
Reference: TSSA Gas Technician 1 Study Guide, 2026 Edition, Section 4.3.2
Q2. A technician is commissioning a propane-fired boiler with a manifold pressure of 10 inches water
column. The burner input rating is 200,000 BTU/hr. The specific gravity of propane is 1.52. Using the gas
orifice sizing formula, what is the required orifice diameter (in inches) for a single orifice burner? Assume a
discharge coefficient of 0.65 and a gas temperature of 60°F.
A. 0.125
B. 0.1875
C. 0.25
D. 0.3125
Correct Answer: B. 0.1875
Rationale: The orifice diameter is calculated using the formula Q = 0.65 * A * sqrt(2 * ”P / Á), where Q is flow
rate, A is area, P is pressure drop, and is gas density. With propane's higher specific gravity, the required
diameter is 0.1875 inches (3/16 inch).
Why Wrong:
A - 0.125 inch (1/8 inch) would be too small for the given input and pressure.
C - 0.25 inch (1/4 inch) would overfire the burner, exceeding the rated input.
D - 0.3125 inch (5/16 inch) would cause excessive gas flow and potential safety hazards.
Reference: CSA B149.1-20 Natural Gas and Propane Installation Code, Annex E
Page 3
, Q3. A gas-fired rooftop unit is equipped with a redundant gas valve system consisting of two solenoid valves
in series. During a safety shutdown, the valve train must be proven to be leak-tight. According to the latest
ANSI Z21.20 standard, what is the acceptable leakage rate for each valve when tested at 1.5 times the
maximum inlet pressure?
A. 0.1% of rated capacity per hour
B. 0.5% of rated capacity per hour
C. 1.0% of rated capacity per hour
D. No measurable leakage is permitted
Correct Answer: D. No measurable leakage is permitted
Rationale: ANSI Z21.20 requires that safety shutoff valves have no measurable leakage when tested at 1.5 times the
maximum inlet pressure. The other options allow leakage, which is not acceptable for redundant valves.
Why Wrong:
A - 0.1% leakage is not allowed; zero leakage is required for safety valves.
B - 0.5% leakage is not permitted under the standard.
C - 1.0% leakage is far above the allowable limit.
Reference: ANSI Z21.20-2020, Section 2.3.1
Q4. A technician is troubleshooting a natural gas furnace that short cycles on the high-limit switch. The
supply air temperature rises rapidly to 200°F, causing the burner to shut off. The furnace is rated at 100,000
BTU/hr with a temperature rise of 70°F. The actual airflow measured is 800 CFM. What is the most likely
cause of the short cycling?
A. Oversized burner orifice
B. Restricted return air filter
C. Faulty gas valve
D. Improperly adjusted pressure regulator
Correct Answer: B. Restricted return air filter
Rationale: With a temperature rise of 70°F and 100,000 BTU/hr, the required airflow is approximately 1,200 CFM
(using the formula BTU/hr = 1.08 x CFM x T). The actual 800 CFM is too low, causing overheating. A restricted
filter reduces airflow, leading to high temperature rise and short cycling.
Why Wrong:
A - An oversized orifice would increase input but not necessarily cause rapid temperature rise if airflow is
adequate.
C - A faulty gas valve would likely cause inconsistent firing or no flame, not short cycling on high limit.
D - An improperly adjusted regulator might affect manifold pressure but airflow is the primary issue here.
Reference: ASHRAE Handbook-HVAC Systems and Equipment, 2020, Chapter 32
Page 4
