To verify a TSSA licence before hiring, ask for two separate things: the technician's TSSA fuels certificate card, and the company's TSSA contractor registration. Then confirm both with the Technical Standards and Safety Authority rather than taking a badge on a website at face value. In Ontario the person doing gas work and the business employing them are certified separately, and a company can hold a valid registration while the individual standing on your basement floor does not hold a current certificate.
It takes about ten minutes and it is the only part of choosing a contractor that has a yes-or-no answer. A furnace, a water heater, a gas fireplace and a pool heater are all fuel-burning appliances, and the difference between a competent installation and a carbon monoxide problem is invisible from the top of the stairs.
The Two Credentials You Are Actually Checking
There are two, and you need both. Individuals hold a fuels certificate issued by TSSA — G1, G2 or G3 for natural gas and propane, or an oil burner technician certificate for oil. Businesses hold a TSSA contractor registration, which is what allows the company to take on the work and sign off on it.
- G3 — the entry-level certificate. Restricted to appliances up to 400,000 BTU/h input and required to work under the supervision of a G2 or G1.
- G2 — the certificate most residential furnace, water heater and fireplace work is done under. Appliances up to 400,000 BTU/h, unsupervised.
- G1 — no BTU limit. This is the level required for larger commercial and industrial equipment: rooftop units, make-up air, boiler rooms.
- Oil burner technician (OBT) — a separate certification stream for oil furnaces and oil-fired water heaters, which still heat homes in rural Flamborough and north Burlington beyond the gas mains.
- Contractor registration — held by the business, not the person. Ask for the number and the legal name it is registered under, and check that the legal name matches the name on your quote and your invoice.
What a Real TSSA Card Looks Like, and the Three Things to Read
Read the class, the name and the expiry date, in that order. The card is a wallet-sized certificate showing the holder's name, the certificate class, a certificate number and an expiry date. Fuels certificates are renewed on a cycle, so a lapsed card means that person is not certified today no matter how many years they have been in the trade.
- Name — does it match the person in front of you and the name on the quote? Photograph the card if you like; a technician with nothing to hide will not mind.
- Class — a G3 alone on a furnace changeout, with no G2 or G1 on site, is a problem with the job before it starts.
- Expiry — the line people skip. Certificates lapse quietly, nobody announces it, and a card that expired in March is not a licence in November.
- Certificate number — this is what you need if you want to confirm the certificate independently rather than trusting the laminate.
How to Confirm It With TSSA Instead of Taking Their Word
Go to the source. TSSA is the provincial authority that administers Ontario's fuels safety programs, holds the contractor registrations and can tell you whether a registration is active. Phone their customer contact centre with the registration number and the exact legal business name, and ask whether that registration is current and in good standing. If a contractor will not give you a number to check, that refusal is itself the answer.
Two more registries are worth the same five minutes. WSIB coverage can be confirmed through a clearance certificate obtained from WSIB's own online service, and a certificate of liability insurance should arrive from the insurer or broker rather than as a screenshot forwarded by the contractor. Nothing obliges you to accept a photo of a document. The broader checklist lives in should my HVAC technician be licensed and insured.
Free quotes, written pricing.
The Refrigerant Card Nobody Asks For
Gas certification does not cover refrigerant. Anyone opening the sealed circuit on your air conditioner or heat pump needs a separate ozone depletion prevention certification, tied to Ontario's Ozone Depleting Substances and Other Halocarbons regulation. It is a different card from a different training stream, and it is the one homeowners almost never think to ask about.
It matters more now than it did five years ago, because the industry is moving to A2L refrigerants such as R-32 and R-454B, which are mildly flammable and carry handling, storage and leak-detection rules that older systems never had. We walked through what changes for homeowners in the A2L refrigerant transition guide.
A Licence Check Is Not a Permit Check
A certified technician still has to pull a permit for most equipment changes, and that is a separate question you should ask in the same conversation. Furnace and gas appliance work in Burlington goes through the City of Burlington building department, Oakville through the Town of Oakville and Hamilton through the City of Hamilton. Permit costs across the GTA typically fall in the $100–$300 range and should already sit inside the quoted price rather than appearing later.
If one quote is cheaper because it has no permit line, you are not comparing the same job. Our municipal walkthroughs cover the local process in detail: HVAC permits in Burlington and HVAC permits in Oakville. Anything we install under furnace installation includes the permit and the inspection coordination.
Red Flags That Show Up on Real Quotes
- The words licensed and insured painted on a truck, with no number offered when you actually ask for one.
- A quote issued under one business name and an invoice issued under another — registration follows the legal entity, so the mismatch matters.
- A technician who tells you the permit is optional on a like-for-like furnace swap.
- Cash-only pricing with no written scope, no model number and no warranty terms.
- Someone willing to touch your gas piping who cannot produce a G-class certificate at all.
- A quote that will not survive a phone call to the manufacturer to confirm the model actually exists in that configuration.
What This Looks Like at Our Shop
ZK Mechanical is owner-operated out of 4145 North Service Road in Burlington, Zobir has been in the trade for more than 15 years, every gas technician who touches your equipment is TSSA-licensed, and the company is fully insured. Ask us for the certificate and the registration on the first visit — we would rather you got into the habit with everyone. If you already have a quote in hand and want a second read on it, send it over and we will tell you what we would verify first.
Frequently asked questions
Is a TSSA licence the same thing as a business licence?
No. A municipal business licence says a company may operate in that city. A TSSA contractor registration says the business is authorized to carry out fuels work in Ontario, and a TSSA fuels certificate says the individual technician is qualified to do it. Check the registration and the certificate; the business licence tells you nothing about gas competence.
Can a G3 technician install my furnace?
Not on their own. A G3 certificate is restricted to appliances up to 400,000 BTU/h and requires supervision by a G2 or G1 technician. G3 holders are often apprentices doing real, useful work — the issue is only whether a certified supervisor is present and accountable for the installation.
Does an HVAC company need TSSA registration to install an air conditioner?
A straight air conditioner with no gas work involved is not fuels work, so a fuels certificate is not what governs it. Refrigerant handling certification is, and the electrical side falls under the Ontario Electrical Safety Code, enforced by the Electrical Safety Authority. In practice almost every established Ontario HVAC company holds both the fuels registration and refrigerant certification, because most homes need both trades in the same basement.
How do I check that a contractor's insurance is real?
Ask for a certificate of insurance issued directly by the insurer or broker, showing the policy number, the coverage limits and the expiry date, with your name added as a certificate holder if you want the strongest version. Call the broker listed on it. A forwarded image proves only that an image exists.
What happens if unlicensed gas work is discovered later?
It typically has to be corrected to code at the homeowner's expense, and a licensed technician who finds an unsafe condition is obliged to tag the appliance. Your insurer may also take a position on unpermitted or uncertified work when assessing a claim, so ask your broker how your specific policy treats it rather than assuming.