Gasfitter (Class A) Exam Questions and Answers PDF — Free 50-Question Mock Exam

What's inside

• 50 original exam-style questions drawn from the six topic areas used in our Gasfitter (Class A) bank — Gas Supply, Appliances, Venting, Combustion, Piping and Safety
• Every answer explained in the back of the PDF, so a wrong answer turns into something learned, not just a lost mark
• Works offline — study in the lunchroom, the truck, or anywhere without a signal. No account needed.

Want every question?

This mock exam is a 50-question slice. The Gasfitter (Class A) Complete Question Bank has all 110 questions with a full explanation for every answer, organized by the six topic areas of our practice bank, in one printable offline PDF.

Corrections to the question banks are listed with dates on the question bank updates page.

The 110-question bank, area by area

The free PDF is a 50-question slice of a 110-question pool, organized by this site's own topic areas. Here is how those 110 break down and what to check in each.

• Appliances & Equipment — 24 questions The widest area: furnaces, boilers, water heaters, fireplaces and dryers, plus the components inside them — thermocouples, combination gas valves, hot surface ignitors, inducer motors, rollout limit switches, aquastats, dip tubes. Much of it is control-sequence knowledge: what proves flame, what breaks the circuit, what order a boiler is commissioned in. For each component, know the condition that operates it as well as its purpose — be able to say what trips a rollout switch, not only point to it.
• Gas Supply Systems — 19 questions Everything upstream of the appliance: service and appliance regulators, two-stage propane regulation, lockup pressure, excess flow valves, meters, odourant, and the gas properties that drive the design — specific gravity, heating value per cubic foot, propane vapour pressure against temperature. Propane and natural gas behave differently at nearly every one of those points, so keep the two apart.
• Piping Systems — 16 questions Material selection, approved thread sealant, drip legs, support spacing, sleeving through foundation walls, underground corrosion protection, and CSST bonding. CSST bonding is not ordinary grounding continuity: it is protection against lightning-induced arcing, which is the hazard it actually addresses. For sizing, remember that pressure drop rises with flow.
• Venting Systems — 20 questions The four appliance venting categories and what each demands, B-vent against sealed combustion against condensing-appliance plastic vent, connector pitch, common venting of two appliances, clearances from a termination to windows and doors, and spillage testing. Learn the category system: keep Category I and Category IV apart, because vent material follows directly from the category.
• Combustion Theory — 16 questions Stoichiometric combustion, primary against secondary air, what excess air does to efficiency, flame appearance as a diagnostic, flue-gas CO₂ and stack temperature readings, the conditions that generate carbon monoxide, and flame rectification. This area rewards understanding over memory: explain why excess air raises stack temperature and lowers efficiency and most analyser questions answer themselves. Memorising a target CO₂ figure without the relationship behind it fails as soon as the numbers change.
• Safety & Code — 15 questions Leak response and when a building gets evacuated, what CSA B149.1 governs, carbon monoxide symptoms and detector placement, permits, purging a new system before lighting appliances, and the scope difference between a Class A and a Class B licence. Many of these are sequence questions rather than fact questions — "what is the FIRST action" has one correct order, and a sensible-sounding step in the wrong position is still marked wrong.

Working through the 50 in one sitting

Sit the whole 50 with a clock running and practise finding clauses quickly in B149.1: SkilledTradesBC provides B149.1, B149.2 and B149.3 at the Red Seal exam in BC, so check what your own jurisdiction provides.

Mark every question you guessed, score it, then sort the misses into two piles. One pile is numbers you did not know — clearances, pressures, support spacing, CO₂ targets. That pile is flashcard work and it clears quickly. The other pile is mechanisms you did not understand: why CSST is bonded, why venting category dictates material, why excess air costs efficiency. That pile is slower; do not skip it.

Watch for a propane-versus-natural-gas pattern running through your wrong answers. If they concentrate on LP questions across Gas Supply and Piping, that is one gap, not six. The same goes for venting: if Category III and IV questions cost you marks, relearn the category table once rather than the individual questions.

How gasfitter certification is regulated in Canada

Gas work is regulated province by province, and the picture is not uniform. Gasfitter — Class A is a Red Seal designated trade in Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, the Northwest Territories, Nunavut, Prince Edward Island, Quebec and Yukon. It is not on the Red Seal designation list for Ontario or Saskatchewan, and each jurisdiction sets its own start date for exams built on the newer occupational standard for this trade (SkilledTradesBC: October 26, 2026 in BC), so check with your provincial or territorial apprenticeship authority whether they are in use where you write (checked October 2026).

Ontario certifies gas work through its provincial fuels safety regime rather than through Red Seal designation. Certificates are issued under Ontario Regulation 215/01 in categories including G.3, G.2 and G.1, training is delivered by accredited providers using an approved curriculum, and a G.3 holder works under the general supervision of a G.1, G.2 or DA certificate holder.

So check what your own jurisdiction issues before planning around a certificate name. The six topic areas in this bank are the working knowledge base behind gas certification wherever you are, because CSA B149.1 is the common code reference across the country. But this is independent study material: it carries no credit, satisfies no requirement, and working through it does not lead to a Red Seal endorsement or a provincial gas certificate. For the same reason this page prints no question count, time limit or passing mark for any gasfitter exam other than the Red Seal one — provincial gas certificates set their own. For the Red Seal Gasfitter — Class A exam itself, red-seal.ca lists 100 questions, and its exam preparation guide gives a 70% pass mark and four hours of writing time (checked September 2026).

Questions gas apprentices ask about this PDF

• Does it cover propane as well as natural gas? Yes, both run right through the bank. Propane turns up in supply (two-stage regulation, vapour pressure, tank behaviour in cold weather), in piping (which copper tubing the code accepts for LP), and in the combustion figures.
• Which code edition do the questions follow? They work from CSA B149.1 concepts that hold across editions, but specific clearances and requirements can change with the edition your province has adopted. Check the current adopted edition and its amendments before treating any figure as final.
• Is this useful for Ontario G.2 or G.3 study? The underlying knowledge overlaps heavily, since B149.1 is the common reference. But Ontario's certification follows an approved curriculum with its own defined scope per category, so treat this as supplementary practice, not a substitute for accredited training.
• Are these real exam questions? No. Every one is original, written against this site's own topic areas for the trade. Live exam banks are secure and are not published by anyone.