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Straight answers
The questions people ask most about getting certified and starting and running a gas fitting business in Ontario. Answered straight, with links to the official sources.
Fast — it's the quickest regulated trade to enter. An accredited Gas Technician 3 (G3) program runs weeks to a few months, and once you pass the TSSA exam you can work on smaller residential appliances under a G2/G1. Climbing to G2 (and the broader work) takes field experience plus the next program and exam, but you're earning in the trade far sooner than the five-year compulsory trades.
They're defined by appliance input (BTU) capacity. G3 is entry-level and limited to lower-input residential appliances, working under supervision. G2 covers most residential and light-commercial gas equipment — the level most independent gas work happens at. G1 is unlimited input for large commercial and industrial. You progress G3 → G2 → G1 with experience and exams.
Pairing is the career — gas alone is narrow. With HVAC (313A/313D) you become a full heating tech, which is where most residential mechanical money is, since furnaces and boilers are gas. With plumbing (306A) you cover water heaters, boilers, and gas lines as a residential service combo. Either combination is far more valuable and employable than a standalone gas ticket.
You can work, but the scope is narrow — most gas-only techs end up doing furnace and water-heater work for an HVAC or plumbing company. The strong earners use gas as one ticket among several (HVAC or plumbing), which lets them own the whole job rather than just the gas connection.
In winter, real — no-heat calls cluster in cold snaps, and gas/heating service is exactly the kind of emergency work that runs nights and weekends in season. It pays (premiums, callouts), and it builds your skills fast, but it's a reason a lot of gas/HVAC techs eventually move toward day-shift, sales, or ownership where they control the rotation.
Hold a G2 or G1, register your business as a fuels (gas) contractor with the TSSA, and carry liability insurance and WSIB. Most gas businesses are really HVAC or plumbing businesses with the gas ticket attached, because that's how you get enough scope to fill a schedule and own the full job.
Yes. Gas work is regulated by the TSSA. You need a gas technician certificate — G3 (limited residential input), G2 (most residential and light commercial), or G1 (unlimited) — and the business must be a TSSA-registered gas contractor.
G3 is an entry-level certificate limited to lower-input residential appliances and must work under a G2 or G1. G2 covers most residential and light-commercial gas appliances. G1 is unlimited input, covering large commercial and industrial equipment. You progress G3 → G2 → G1.
Hold a G2 or G1 gas technician certificate, incorporate, register your business as a gas contractor with the TSSA, and carry liability insurance and WSIB. Many gas fitters also hold plumbing or HVAC tickets because the work overlaps with water heaters, boilers, and furnaces.
A sole proprietorship is cheaper and simpler to start, but you are personally liable for the business's debts and claims. Incorporating creates a separate legal entity that limits personal liability, can reduce tax once you are profitable, and reads as more credible to larger clients. Most contractors incorporate once they have employees, real revenue, or work on others' property.
Yes — construction is a mandatory WSIB sector in Ontario. Even independent operators and partners with no employees generally must register, and clients and general contractors will require a valid WSIB clearance certificate before you can work on their site.
You must register for and charge HST once your revenue exceeds $30,000 over four consecutive quarters. Many contractors register before that threshold so they can claim input tax credits on tools, materials, and vehicles from day one.
Ontario's Construction Act sets the rules: a 10% holdback on most contracts, prompt-payment timelines (you must be paid within set periods after a proper invoice), and an adjudication process for disputes. Understanding holdback, lien rights, and prompt payment is essential to protecting your cash flow.