Quick answer
A home inspection is not enough to clear a furnace and AC. Ontario home inspectors work to standards that are visual and non-invasive: they run the equipment from the thermostat and do not dismantle it or test combustion. Add an inspection by a licensed gas technician when the equipment is over about 12 years old, rented, a boiler, visibly rusted, or when the AC cannot be run.
Is a home inspection enough to check the furnace and AC? It is enough to tell you the equipment exists, turns on and roughly how old it is. It cannot tell you whether a 14-year-old furnace has a cracked heat exchanger or whether the air conditioner is low on refrigerant, because the inspector's own standards exclude the tests that would show it. On older equipment, the gap between those two answers can be the price of a new system.
What an Ontario home inspector does and does not do
Home inspectors in Ontario work to a standards of practice document, most often the one from the Ontario Association of Home Inspectors or the Canadian Association of Home and Property Inspectors. Both describe a visual, non-invasive look at readily accessible components. Under those standards the inspector will:
- Open the access panels a homeowner would open, and look.
- Operate the furnace and AC with normal controls, meaning the thermostat.
- Describe the fuel, the type of equipment and its approximate age from the data plate.
- Report visible rust, staining, a missing filter or venting that looks wrong.
The same standards say what the inspector is not required to do:
- Dismantle anything. The burner compartment, the blower and the coil stay closed.
- Inspect the heat exchanger, which cannot be seen without a camera or removing parts.
- Test combustion, carbon monoxide in the flue gas or gas pressure.
- Connect gauges to the refrigerant circuit.
- Run the air conditioner in cold weather, because starting a compressor when it is cold outside can damage it.
A careful inspector says so in the report. 'Recommend evaluation by a licensed HVAC contractor' is a real recommendation, not boilerplate.
What only a licensed gas technician can check
- The heat exchanger, with an inspection camera: cracks and rust-through that let combustion gases into the house air. Replacing one costs $1,500–$3,000, and on a furnace past 15 years that money is better put toward a new furnace.
- Combustion analysis: a probe in the flue reads oxygen, carbon monoxide and efficiency while the furnace runs. High CO in the flue is a finding no visual check produces.
- Gas pressure at the valve and temperature rise across the furnace, each compared with the rating plate.
- Venting: slope, joints, termination clearances and aged materials on mid-efficiency furnaces.
- Refrigerant charge and compressor health: superheat, subcooling and amp draw, taken by a technician with an ODP card in weather warm enough to run the system.
- Ownership: a rental sticker means the furnace or water heater comes with a contract the buyer is asked to assume.
When to add an HVAC inspection to your offer
- The furnace or AC is over about 12 years old. Replacement is close enough to affect the price you offer: $4,500–$7,500 for a high-efficiency furnace, $7,500–$11,500 for furnace and AC together.
- The equipment is rented. Read taking over a furnace rental when buying a house before you agree to assume it.
- The house has a boiler, radiators or in-floor heat. Expansion tanks, relief valves and circulators need a technician who works on hydronic systems.
- There is visible rust on the burners or the cabinet floor, water staining under the furnace, scorch marks, or a vent that is taped, sagging or sloped the wrong way.
- It is a winter purchase. The AC cannot be run, so nobody has tested it; ask your agent about a holdback or a seller warranty on the cooling until spring.
- The property is a century farmhouse or a rural lot on oil or propane, where the tank's age and condition are a separate question from the furnace.
What you get from the HVAC inspection that the home inspection report lacks
You get measured numbers, photos from inside the heat exchanger and a plain verdict: serviceable, serviceable with listed repairs, or at end of life. That is a document you can negotiate with, and it fits inside most conditional periods if you book it the day the offer is accepted. Weigh the findings against the repair and replacement bands on the pricing page, and for the oldest equipment see buying a house with a 20-year-old furnace.
ZK Mechanical's HVAC inspection for buyers is carried out by a TSSA-licensed gas technician, with the findings in writing. Buying in Burlington, Oakville, Milton, Hamilton or Mississauga? Call (647) 801-1252 or book the inspection as soon as your offer is conditional. The fee depends on how many systems the house has and is confirmed when you book; more buyer questions are in the costs and buying library.