Furnace Maintenance Checklist for Toronto Homes: 5 Steps Before the Cold Hits

What should you do to get your furnace ready for winter in Toronto? Do five things: replace the filter, clear the space around the furnace, run a test cycle, book a yearly tune-up with a licensed technician, and test your carbon monoxide (CO) alarm. Most take less than an hour, and you can do the first three yourself this weekend.

The first cold night is a bad time to find out something is wrong. A furnace that sat idle all summer can have a clogged filter or a fault nobody noticed. A quick check now beats an emergency call at 2 a.m.

This is a practical checklist for homeowners in Toronto and surrounding areas, with what to do yourself and what to leave to a professional.

Step 1: How often should you replace your furnace filter?

Check it at least every three months and replace it when it’s dirty. Homes with pets or smokers may need to check it more often. Your furnace manual has the exact size and schedule for your model. 

The test is simple. Slide the filter out and hold it up to the light. If you can’t see through it, swap it. A clogged filter makes your furnace work harder and can shorten its life.

Step 2: Why does your furnace need clear space around it?

Furnaces need airflow. Boxes, laundry and storage piled against the unit can block that air, and they don’t belong near a fuel-burning appliance anyway. Keep the area well back and tidy. This takes five minutes, and it matters in finished basements where the furnace is tucked into a utility corner.

Step 3: Should you test your furnace before it gets cold?

Yes. Turn the heat up on a mild day and let a full cycle run. Listen for banging, squealing or rattling, and notice any unusual smells. A brief dusty smell on first start-up is common. A strong or lingering smell is not.

If you smell gas (a rotten-egg odour), leave the home right away and call your gas utility from outside. Utility emergency response is free to the homeowner; only the repair itself is billed. 

Step 4: Do you need a professional furnace tune-up every year?

Yes. Filters and tidying are things you can do yourself, but gas work is not. In Ontario, only fuel contractors registered with TSSA and individuals holding a valid gas technician certificate are legally permitted to work on fuel-fired appliances. TSSA recommends that a licensed gas technician inspect your equipment every year. 

A few tips when booking:

• Ask for a TSSA-certified gas technician before you book.
• Book early. Fall is the busiest season, and waiting means waiting in the cold.
• Ask the technician to show you anything they say needs replacing, such as a photo or video.
• Prices vary. One Toronto contractor guide puts a typical tune-up at roughly $150 to $280. Treat that as a rough guide, not a quote.
• Keep your service records. Many manufacturer warranties ask for proof of maintenance, so check yours.

Step 5: How do you test a carbon monoxide alarm, and what are Ontario’s rules?

Carbon monoxide is invisible and odourless, and furnaces are one of the possible sources. The Ontario Fire Marshal says only a working CO alarm can detect it. 

Here is what to do:

• Test your CO alarms every month by pressing the test button.
• Replace the batteries every year. 
• Replace the whole alarm when it reaches end of life, typically 7 to 10 years. 
• Know the sound. An activated CO alarm sounds different from a smoke alarm, with four beeps in quick succession. 
• If it goes off, get everyone outside and call 911 or your fire department.

The rules changed this year. Since January 1, 2026, CO alarms are also required when a home is heated by air from a fuel-burning appliance located outside the home, and alarms must be installed on every storey. If your alarms were installed years ago, check where they are and how old they are. For questions about your specific home, contact your local fire department. Landlords have responsibilities here too. It is illegal to remove the batteries or tamper with a CO alarm.

What if you’re buying or selling a home in Toronto?

If you’re buying: ask how old the furnace is and whether there are service records. A furnace with a documented yearly tune-up tells you the home has been looked after. Check that CO alarms are on every storey. A home inspection will comment on the furnace’s condition, and a licensed technician can give you a closer look before you commit.

If you’re selling: a clean filter, a clear furnace area, recent service records and working alarms cost very little. They show buyers a home that has been cared for. I can’t promise they will change your sale price, but they remove easy doubts.

Your furnace checklist at a glance

1. Replace the filter
2. Clear the space around the furnace
3. Run a test cycle
4. Book a tune-up with a licensed technician
5. Test your CO alarms and check their age

My take

A furnace is one of the most important systems in any Toronto home, and it’s easy to ignore until it fails. The good news is that the highest-impact steps are simple and cheap. Do the filter, the space and the alarm test this weekend, and put the tune-up on your calendar before the rush.

I’m here if you have questions about your home or your next move.

Khoa Le, Real Estate Broker | Real Broker Ontario
Phone: 647-271-5461
Email: khoa@realimpactgroup.com
Instagram: @realimpactgroup | @realbrokerage

This post is general information only. It is not legal, tax, mortgage, or technical advice. Follow your furnace manufacturer’s instructions and have gas appliances serviced by a licensed technician.