By Matthew Arbab, Owner of Aire One Heating & Cooling · Serving Markham and the GTA since 1990
A furnace or air conditioner rarely gets a second look during a showing, but it can be one of the most expensive surprises after you get the keys. Replacing a furnace and central AC in a GTA home can cost several thousand dollars, and some homes come with rental contracts that transfer to the buyer.
We’ve completed more than 120,000 installations across Markham, Richmond Hill, Vaughan and Toronto. This is the checklist we’d give a friend who’s buying a home. Print it, bring it to the showing, and share it with your realtor or home inspector.
Quick summary: the 10 things that matter most
- How old is the furnace, AC or heat pump?
- Is any equipment rented, and is there a notice of security interest on title?
- Are there service and maintenance records?
- Is there a working carbon monoxide alarm near every sleeping area?
- Is the furnace high-efficiency (plastic venting) or older mid-efficiency (metal chimney venting)?
- Does the AC use the phased-out R-22 refrigerant?
- Are there signs of rust, water leaks or soot?
- Does every room get airflow, and is the thermostat working?
- Is any warranty transferable to a new owner?
- What do the last 12 months of gas and hydro bills look like?
1. Check the age of every unit
Every furnace, air conditioner and heat pump has a data plate (rating label) with a model and serial number. The manufacture date is usually printed on it or encoded in the serial number. Ask the seller or listing agent, or snap a photo of the label so a technician can decode it.
| Equipment | Typical lifespan | What it means for you |
|---|---|---|
| Gas furnace | 15–20 years | Older than 15 years? Budget for replacement soon. |
| Central air conditioner | 10–15 years | Older than 12 years? Expect higher repair costs. |
| Heat pump | 10–15 years | Works year-round, so it ages faster than an AC. |
| Thermostat | ~10 years | An old non-programmable unit is a cheap upgrade. |
Lifespans vary with maintenance, sizing and installation quality. These are general ranges, not guarantees.
2. Ask: is any of the equipment rented?
This is the big one for Ontario buyers. Many GTA homes have a rented furnace, air conditioner or water heater. When you buy the home, you may also take over the rental contract and its monthly payments. Some rental companies register a notice of security interest (NOSI) on the property’s title.
- Ask the listing agent in writing: “Is any HVAC equipment or the water heater rented or financed?”
- If yes, get a copy of the contract: monthly cost, years remaining and buyout price.
- Ask your real estate lawyer to check title for any NOSI before closing.
- Make sure the agreement of purchase and sale says clearly who is responsible for the contract.
3. Look for maintenance records
A furnace that’s been serviced every year will usually outlast one that hasn’t. Ask for:
- Annual maintenance invoices or a service sticker on the unit
- The original installation invoice, including the installer’s name and date
- Any recent major repairs (heat exchanger, compressor, blower motor)
4. Safety first: carbon monoxide
In Ontario, homes with a fuel-burning appliance (like a gas furnace, water heater or fireplace) or an attached garage need a working carbon monoxide (CO) alarm next to every sleeping area. During the showing:
- Confirm there are CO alarms outside bedrooms and check their expiry dates (usually printed on the back).
- Look for soot or scorch marks around the furnace or water heater.
- Look for a yellow or flickering burner flame where a viewing window lets you see it. A healthy gas flame is mostly blue.
- Notice any stale or exhaust-like smell near the furnace room.
If you see any of these, ask for a licensed HVAC inspection before you firm up your offer.
5. Venting tells you a lot about efficiency
- White or grey plastic (PVC) pipes exiting through the side wall usually mean a high-efficiency furnace (90%+ AFUE).
- A metal vent connected to a chimney usually means an older, mid-efficiency furnace. It’s often older and costs more to run.
- Make sure outdoor vents aren’t blocked by snow, decks, shrubs or garbage bins.
6. Air conditioner and heat pump checks
- Check the outdoor unit’s label for the refrigerant type. Units using R-22 are older, and R-22 is no longer manufactured or imported in Canada, so repairs can be very expensive.
- The outdoor unit should sit level, with at least 30–60 cm of clearance around it.
- Look for bent fins, rust, or oil stains on refrigerant lines (a possible leak).
- In summer, turn on the AC: the supply air should feel noticeably cooler within a few minutes.
7. Look for water, rust and wear
- Water pooling around the furnace (often from a blocked condensate drain on high-efficiency units)
- Rust on the furnace cabinet or the humidifier underneath it
- A very dirty or missing furnace filter, a sign the system hasn’t been maintained
- Taped-up or disconnected ductwork in the basement
8. Walk the house for comfort
- Hold your hand over vents in every room. Is air coming out?
- Are upstairs bedrooms much hotter or colder than the main floor?
- Does the thermostat respond, and does the system start within a minute or two?
- Any loud banging, squealing or rattling when the system starts?
9. Ask about warranties
Many manufacturer warranties require registration, and some are only valid for the original owner or must be transferred within a set time after the sale. Ask the seller for warranty paperwork and check the transfer rules with the manufacturer or installer.
10. Ask for 12 months of utility bills
Gas and hydro bills from the past year show what the system really costs to run. Unusually high winter gas bills can point to an inefficient furnace, poor insulation or air leaks.
Printable checklist
| ✓ | Item | Notes |
|---|---|---|
| ☐ | Furnace age (from data plate) | |
| ☐ | AC / heat pump age and refrigerant type | |
| ☐ | Any rented or financed equipment? Contract copy received? | |
| ☐ | Lawyer checked title for NOSI | |
| ☐ | Maintenance records / last service date | |
| ☐ | CO alarms near all sleeping areas, not expired | |
| ☐ | No soot, scorch marks or yellow flame | |
| ☐ | Venting type (PVC = high-efficiency / chimney = older) | |
| ☐ | No water, rust or leaking lines | |
| ☐ | Airflow in every room; thermostat works | |
| ☐ | Warranty transferable? | |
| ☐ | 12 months of gas & hydro bills reviewed |
Frequently asked questions
Does a standard home inspection cover the furnace and AC?
A home inspector will usually do a visual check and confirm the system runs. They typically don’t open the furnace to inspect the heat exchanger or test refrigerant levels. For older systems, a separate HVAC inspection by a licensed technician gives you a clearer picture.
Should I walk away from a home with an old furnace?
Not necessarily. An older furnace is a negotiating point, not always a deal-breaker. Get a replacement estimate and factor it into your offer.
Can I get out of a furnace rental contract after I buy?
It depends on the contract. Many have buyout terms. Get the contract and the buyout amount before closing, and have your lawyer review it.
Is it worth switching to a heat pump when I move in?
For many GTA homes, a cold-climate heat pump paired with an existing furnace can lower heating costs and adds central air conditioning. Read our guide: is a heat pump the smartest upgrade for Toronto homes?
Need a second opinion before you buy?
If the furnace or AC raises questions, our Markham heating and cooling team offers a free Total Home Assessment across Markham, Richmond Hill, Vaughan and the GTA. We’ll tell you honestly whether the system has years left or needs a furnace replacement in Markham. Book a visit or call 310-HEAT (310-4328).
Realtors and home inspectors: you’re welcome to link to or share this checklist with your clients. Contact us at metrotoronto@aireone.com for a branded PDF version.
This checklist is general information, not a substitute for a professional inspection or legal advice. Rules and programs can change. Confirm details with a licensed HVAC technician and your real estate lawyer.