How to Verify an HVAC Contractor's License Before They Touch Your Furnace
Last updated: August 2026
Every technician who works on a gas furnace in Ontario must hold a TSSA G2 or G1 certification — this is a legal requirement under the Technical Standards and Safety Act, not a quality badge a company can skip. Ask for the technician's license number before any work begins, then verify it free at tssa.org in under two minutes. Refrigeration and AC work requires a separate 313A or 313D certification through Skilled Trades Ontario. If a contractor won't provide a license number, that's a reason to call someone else.
Is HVAC licensing actually required in Ontario, or just recommended?
It's a legal requirement, not a recommendation. Gas-fired equipment work requires TSSA G2 or G1 Gas Technician certification; refrigeration and AC work requires a 313A or 313D Certificate of Qualification through Skilled Trades Ontario. A general handyman has no legal standing to open a gas appliance, regardless of experience claimed. TSSA reports that roughly 65% of fuels-related incidents in Ontario stem from substandard installation or maintenance work.
What's the difference between a G2 and G1 gas technician?
A G2 technician can work unsupervised on residential gas appliances up to 400,000 BTUH, which covers virtually every home furnace, water heater, and gas fireplace. A G1 covers all gas systems including larger commercial and industrial equipment. A G3 is an apprentice-level certification and must work under supervision — a G3 alone should not be working unsupervised on a home furnace.
How do I actually check a technician's license?
Ask for the license number directly, then look it up free at the TSSA's public technician lookup tool on tssa.org — the check takes under two minutes and confirms both that the certification is active and its grade level. Do this before the technician opens an access panel, not after.
What should I ask a contractor before hiring them?
Ask for their TSSA license number, their company's registered fuels contractor status, and a written, itemized quote before work begins.
| Ask for | Why it matters | Red flag if they can't provide it |
|---|---|---|
| TSSA license number | Legally required for gas work | Immediate red flag |
| Registered fuels contractor name | Technician must work under a registered contractor | Ask before booking |
| Written, itemized quote | Prevents surprise charges | Verbal-only pricing |
| Refrigerant/AC certification (313A/313D) | Separate from gas certification, required for AC/heat pump work | Only relevant if job involves refrigerant |
What if a technician red-tags my furnace — do I have to use their company for the fix?
No. A red tag means the gas is shut off for safety, but you're free to hire any licensed contractor to clear it — you are not obligated to use the company that issued the tag. Get quotes from more than one licensed contractor before committing to a red-tag repair or replacement, and treat "you have to decide today" pressure as a warning sign rather than a genuine deadline.
Deciding whether to repair or replace? See the furnace repair-vs-replace guide. Comparing systems? See heat pump vs. furnace. Read the complete HVAC buyer's guide for more.