Furnace and gas appliance work in Ontario: why only TSSA-registered contractors may do it
In Ontario only TSSA-registered fuels contractors with certified gas technicians may install or service gas appliances. How to check before you hire.
Gas work is where a cheap quote can be dangerous. A badly installed furnace, water heater or gas fireplace can leak gas or carbon monoxide, and it may leave you without insurance coverage. Ontario controls this work through the Technical Standards and Safety Authority (TSSA).
Who may do the work
TSSA says registered fuels contractors are the only businesses legally authorized to do fuels-related work in Ontario. Only contractors registered with TSSA and individuals holding a valid gas technician certificate may work on gas appliances, and registered contractors must employ TSSA-certified gas technicians.
Registration has to be current
Contractor registrations are renewed every year. A business that was registered in the past but did not renew is not authorized now.
How to check
TSSA lets the public check a contractor's authorization online or by calling 1-877-682-8772. Check the company name on your quote, and ask the technician who arrives to show their gas technician certificate.
What enforcement looks like
TSSA publishes convictions. In a December 2025 case a company was fined $10,000 plus a 25% victim surcharge after installing a furnace without a valid TSSA registration. In another case, a person who removed and replaced a gas furnace in a Windsor home without a gas technician certificate, through an unregistered business, was found guilty. TSSA also warns homeowners about fraudulent fuels workers.
Permits and other work
Gas work is separate from any building permit or electrical notification the same project needs; a furnace or heat pump replacement may involve all three. Ask your contractor which ones they will obtain.
Prevention Checklist
- Check the company on TSSA's registered contractor lookup or call 1-877-682-8772.
- Ask the technician for their gas technician certificate.
- Make sure the registration is current this year.
- Ask which permits and notifications the job needs: building, electrical and gas.
- Keep the invoice naming the registered contractor.
References
- TSSA. Authorized Heating Fuel Contractors, Web page, Registered fuels contractors; lookup. Accessed 2026-11-01.
- TSSA. TSSA Cautions Ontario Homeowners Against Hiring Fraudulent Fuels Workers, Web page, Who may work on gas appliances. Accessed 2026-11-01.
- TSSA. Repeat Offender Convicted of Unlicensed Gas Appliance Work in Ontario Homes, Web page, Enforcement example. Accessed 2026-11-01.
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General information based on the official sources listed above, not legal, tax or engineering advice. Rules change; check the source or ask a qualified professional before you act.
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