How do I choose a good HVAC contractor in the GTA?

An HVAC install is one of the largest single purchases most homeowners make, and installation quality affects efficiency and lifespan more than the brand on the box. The GTA has hundreds of contractors ranging from excellent to actively predatory — Ontario's history of furnace-rental door-knocking scams is well documented. Here's a practical vetting process.

Non-negotiable credentials

• TSSA gas licence — in Ontario, anyone working on gas appliances must hold a valid Gas Technician licence (G2 or G1). Ask for it; legitimate techs carry their card.
• Liability insurance and WSIB coverage — protects you if something goes wrong on your property
• Permits — furnace and AC replacements require municipal permits in most GTA cities; the contractor should pull them, not ask you to skip them
• ODP/refrigerant certification for anyone handling AC refrigerant

What separates good from adequate

• Heat-load calculation — a proper contractor measures your home (or at minimum reviews square footage, insulation, and windows) before naming a size. 'Same size as the old one' repeats any original sizing mistake. See what size furnace you actually need.
• Itemized written quotes — equipment model numbers, venting, permits, disposal, and warranty terms in writing, not a single bottom-line number
• Workmanship warranty — 1–2 years on labour in addition to the manufacturer's parts warranty
• Reviews that mention specifics — repeated technician names, punctuality, cleanup, and post-install follow-up are stronger signals than star count. Read what GTA homeowners say about ZK Mechanical.
• They service what they sell — companies with a real maintenance and repair operation will still answer the phone in year five

Red flags

• Door-to-door sales or unsolicited 'free furnace inspection' calls — the classic Ontario rental-contract trap
• Quotes 30–40% below everyone else — usually missing permits, proper venting, or licensed labour
• Pressure to sign today for a 'one-day price'
• Cash-only, no written contract, or reluctance to show licensing
• Condemning your furnace on the spot without showing you evidence (a crack, a measurement)

Use the quote process as a test drive

How a company handles a free quote predicts how it handles a warranty call: Did they measure, or eyeball? Did they explain options at multiple price points without pushing the top one? Did the quote arrive when promised? ZK Mechanical has served the GTA for over 15 years with licensed technicians, upfront flat-rate pricing, and free in-home quotes — we're happy to be one of your three estimates.