Quick answer
Some HVAC contractors will install a furnace you bought yourself, but many licensed ones decline. The manufacturer's warranty on equipment bought online is often void or limited, and the installer still carries the liability for the gas work under their TSSA registration. Expect a labour-only install only if the furnace is new, certified for Canada, correctly sized, and you accept no equipment warranty from the installer.
Will an HVAC contractor install a furnace I bought myself? It is one of the more common calls a shop gets, usually after someone finds a furnace online for well under a contractor's installed price. The honest answer is sometimes, on conditions, and the saving is smaller than the price gap suggests. This is how the decision looks from the installer's side of the table.
Why many licensed contractors say no to customer-supplied furnaces
The first reason is warranty. Several furnace manufacturers state in their warranty terms that equipment sold over the internet, or outside their dealer network, carries reduced coverage or none. A lifetime heat exchanger warranty printed on the brochure can be worth nothing if the serial number traces to a seller the manufacturer does not recognize.
The second reason is liability. In Ontario the gas technician who connects and fires an appliance is responsible for that installation meeting CSA B149.1 and the manufacturer's instructions, and the company answers for it under its TSSA contractor registration. That responsibility does not shrink because the homeowner bought the box. If the furnace arrived with shipping damage or a missing part, the installer finds out on your basement floor with the old furnace already disconnected.
The third is the call-back. When a supplied-and-installed furnace fails in its first winter, the contractor handles the part through their distributor. When a customer-supplied one fails, the homeowner is chasing an online seller for a control board while the house is cold, and paying labour for each visit.
What a labour-only furnace install still requires
- A Canadian certification mark on the rating plate, such as CSA, cULus, ULC or cETL. Gas appliances installed in Ontario must be approved for use here, and a unit carrying only a US mark cannot legally be connected.
- The right size. Input BTU has to match the house's heat loss and the duct system, not the old furnace's nameplate; our furnace sizing guide explains why 1970s–90s subdivision homes so often have oversized units.
- A sealed, new unit with its installation manual, and proof of purchase from a seller you can reach.
- The parts that do not come in the box: vent pipe and termination kit, condensate trap and pump or neutralizer, gas shut-off, drip leg and connector, filter rack, sheet-metal transitions, thermostat wire.
- The correct fuel. Furnaces ship set up for natural gas; on rural lots in Caledon, Flamborough, Kilbride or Campbellville that heat with propane, the manufacturer's conversion kit for that exact model is needed and a licensed gas technician has to fit it.
- A signed scope stating that the installer warrants their workmanship only, that the equipment carries no warranty from them, and what a return visit costs if the unit itself is defective.
Does buying the furnace yourself save money?
Less than it looks. A contractor's installed price covers the equipment, venting, gas and electrical connection, removal of the old unit, commissioning, warranty registration and a labour warranty. Take the equipment out and most of the labour and materials remain. Compare the totals, not the box price:
- Supplied and installed by one contractor: $4,500–$7,500 for a high-efficiency furnace, with parts and labour warranty and one company to call.
- Customer-supplied: your purchase price, plus a labour-only quote, plus venting and fittings, with no equipment warranty from the installer.
- Each later visit to diagnose a customer-supplied unit: a service call of $90–$150, with the repair billed on top.
The retail route is a different arrangement, because the store arranges the installer; buying a furnace from a big-box store versus a contractor compares the two.
Water heaters and mini-splits bought at retail follow different rules
Tank water heaters are the exception. Retail tanks are sold with consumer warranties that do not depend on a dealer network, and labour-only installs of a store-bought tank are routine, provided a licensed gas technician does the gas connection and venting. The checks are the vent type (atmospheric, power vent or direct vent has to match the house) and the tank's dimensions. Whether you can install your own water heater in Ontario covers the licensing side.
Ductless mini-splits and central heat pumps sit at the other end. Opening a refrigerant circuit in Ontario requires an ODP card, the line set has to be pressure-tested and pulled into a deep vacuum, and refrigerant equipment has the tightest warranty rules of anything in the house: compressor coverage is commonly tied to installation by a licensed contractor. Units sold online as do-it-yourself kits are the hardest equipment to get commissioned, because the installer inherits a sealed-system warranty problem they did not create.
What to ask before you order a furnace online
- Ask the seller, in writing, whether the manufacturer's warranty applies to an internet sale in Ontario and who processes a claim.
- Call the installer before you buy, with the model number. A contractor who will take the job wants to see the specification sheet first.
- Check the return policy for a unit that turns out to be the wrong size or the wrong vent configuration.
- Read what voids a furnace warranty before the box is opened.
ZK Mechanical quotes furnaces supplied and installed, with the model, price and warranty written down before work starts. If you already own the unit, call (647) 801-1252 with the model number and we will tell you plainly whether it is one we can put in and what the scope would be. Otherwise, start with a free written quote for furnace installation through the contact page.