Quick answer: the furnace maintenance checklist
This furnace maintenance checklist covers the jobs Ottawa homeowners can do themselves and the ones best left to a licensed technician.
Monthly in heating season
Check the filter, test CO alarms, look at the vent pipes outside, and listen for new noises.
Filter
Replace 1-inch filters every 1–3 months; 4–5 inch media filters every 6–12 months.
Every fall
Book a professional tune-up, replace the humidifier pad, and open the humidifier bypass damper.
During snowstorms
Keep the exhaust and intake pipes clear of snow.
Every spring
Turn off the humidifier water, close the bypass damper, and get the AC ready.
Professional tune-up cost
Typically $120 – $200 per system in Ottawa.
Monthly checklist (October to April)
These checks take about ten minutes. Doing them once a month through the heating season catches most problems before they leave you without heat.
Check the filter.
Slide it out and hold it up to a light. If you can’t see light through it, replace it.
Test your carbon monoxide alarms
Using the test button. Ontario requires CO alarms near sleeping areas in homes with a fuel-burning appliance.
Look at the outdoor vent pipes.
High-efficiency furnaces vent through two PVC pipes on an outside wall. Make sure they are clear of snow, ice, leaves and nests.
Check the condensate drain.
Look for water around the furnace, a kinked drain hose, or a condensate pump that isn’t running.
Keep the area clear.
Leave at least a metre of space around the furnace. Don’t store paint, solvents or cleaners nearby.
Open the vents.
Keep supply registers open and return grilles free of furniture, rugs and boxes.
Listen and look.
New noises, a burning smell that lingers, or water where there wasn’t any before are signs to call a technician.
Checking regularly matters. In two furnace replacements we handled, a furnace that nobody had been checking failed and a water line burst, and the homeowners ended up paying for a new furnace, flooring and a drywall ceiling.
Seasonal furnace maintenance checklist
| Season | What to do |
|---|---|
| Fall (September – October) | Book a professional tune-up. Replace the filter and humidifier pad. Open the humidifier bypass damper and water valve. Test CO and smoke alarms. Run the heat once before the first cold night. |
| Winter (November – March) | Monthly filter checks. Clear vent pipes during and after snowstorms. Adjust humidity as outdoor temperature drops. Watch for frost or ice on windows. |
| Spring (April – May) | Turn off the humidifier water and close the bypass damper. Replace the filter. Book your AC tune-up and clear debris from around the outdoor unit. |
| Summer (June – August) | Check the filter every month or two, since the furnace blower runs for the AC. Keep the condensate drain clear. |
Snowstorms and your furnace
Heavy snowfall can bury the exhaust and intake pipes on the side of your house. When that happens, the furnace’s pressure switch shuts it down for safety.
During a heavy storm, clear the area around the pipes every couple of hours. Use a broom or your hands, not a shovel, so you don’t crack the pipes.
Furnace filters: what to buy and how often to change them
The filter is the single most important part of homeowner maintenance. A clogged filter makes the blower work harder, raises your gas use and can overheat the heat exchanger.
| Filter type | Replace every | Notes |
|---|---|---|
| 1-inch pleated | 1 – 3 months | Monthly if you have pets, allergies or renovation dust |
| 4–5 inch media filter | 6 – 12 months | Holds more dust with less airflow restriction |
| Washable / electrostatic | Clean monthly | Must dry fully before reinstalling |
A MERV 8 to 11 filter suits most homes. Very high-MERV 1-inch filters can restrict airflow on some furnaces, so check what your system can handle.
Install the filter with the airflow arrow pointing toward the furnace. For more detail, read is it important to change my furnace filter.
Humidifier pad and winter humidity
If your furnace has a bypass or fan-powered humidifier, replace the water panel (humidifier pad) at the start of every heating season. A pad clogged with minerals stops adding moisture and can grow mould.
In the fall, open the bypass damper on the duct and turn on the water valve. In spring, close both.
How much humidity to aim for
Indoor humidity of 30–40% feels comfortable in winter, but as it gets colder outside you need to lower the setting to prevent condensation and frost on windows.
| Outdoor temperature | Suggested indoor humidity |
|---|---|
| Above 0 °C | 35 – 40% |
| 0 °C to −10 °C | 30 – 35% |
| −10 °C to −20 °C | 25 – 30% |
| −20 °C to −30 °C | 20 – 25% |
| Below −30 °C | 15 – 20% |
Our post on humidifiers in Ottawa winters explains why humidity matters for comfort and for wood floors and trim.
Carbon monoxide alarms
Carbon monoxide is colourless and odourless, so an alarm is the only reliable way to know it is present. In Ontario, homes with a fuel-burning appliance, fireplace or attached garage must have CO alarms next to sleeping areas.
- Test each alarm monthly with the test button.
- Replace batteries at least once a year, or as the manufacturer recommends.
- Replace the whole alarm by the end-of-life date printed on it.
- If an alarm sounds, get everyone outside and call 911. Don’t go back in to find the source.
Read our full guide to furnace carbon monoxide safety.
What a professional furnace tune-up covers
Homeowner checks keep a furnace running well, but they can’t replace a yearly inspection by a licensed gas technician. In Ottawa, a tune-up typically costs $120 – $200 per system.
A thorough tune-up includes:
- Inspecting the heat exchanger for cracks or corrosion
- Cleaning the burners and flame sensor, and checking the ignitor
- Testing the pressure switch, inducer motor and high-limit safety switch
- Checking gas pressure and combustion, including a CO check
- Measuring temperature rise across the heat exchanger
- Inspecting and cleaning the blower, and checking motor amperage
- Checking the condensate trap, drain and pump
- Inspecting vent pipes and connections for leaks or blockages
- Checking wiring, the control board and thermostat operation
Yearly maintenance is also the best protection against a cracked heat exchanger, which can let carbon monoxide into your home and usually means replacing the furnace.
What to leave to a technician
Don’t open the burner compartment, adjust the gas valve, or bypass a safety switch to get a furnace running. Gas work in Ontario is regulated by the TSSA and must be done by a licensed gas technician.
If the furnace won’t stay on after you have checked the filter, thermostat, breaker and vent pipes, call for service.
Book your furnace tune-up
Oria has maintained furnaces in Ottawa since 2005, and every technician holds gas and refrigeration licences. Nicole wrote: “Excellent service from Mansoor. Quick response, and very clean work!”
Book a tune-up through our furnace maintenance service, or ask about a maintenance plan that covers your furnace and AC every year. Call (613) 866-1869.
Frequently Asked Questions
How often should a furnace be serviced?
Once a year, ideally in September or October before Ottawa’s heating season starts. A yearly tune-up lets a licensed technician clean the burners and flame sensor, test safety switches, check gas pressure and inspect the heat exchanger for cracks. Many manufacturers also expect regular maintenance as part of their warranty terms, so keep your service records.
How often should I change my furnace filter in winter?
Check a 1-inch filter every month during the heating season and replace it every one to three months, or monthly if you have pets, allergies or renovation dust. Thicker 4–5 inch media filters usually last six to twelve months. If you can’t see light through the filter when you hold it up, it is time to change it.
When should I replace my furnace humidifier pad?
Replace the humidifier pad, also called a water panel, once a year at the start of the heating season. In Ottawa, minerals in the water build up on the pad and stop it from adding moisture. A clogged pad can also grow mould. If you have hard water or run the humidifier heavily, you may need to replace it mid-winter too.
What does a furnace tune-up cost in Ottawa?
A professional furnace tune-up typically costs $120 to $200 per system in Ottawa. It includes cleaning and inspecting the burners, flame sensor, ignitor and blower, testing safety controls, checking gas pressure and combustion, and inspecting the heat exchanger and venting. A maintenance plan can cover your furnace and air conditioner each year so you don’t have to remember to book.
What furnace maintenance can I do myself?
You can check and replace the filter, test carbon monoxide alarms, keep vents and returns open, clear snow from the outdoor vent pipes, check the condensate drain, replace the humidifier pad, and keep the area around the furnace clear. Leave the burners, gas valve, electrical controls and heat exchanger inspection to a licensed gas technician, as Ontario requires.
What should I do with my furnace during a snowstorm?
Check the PVC exhaust and intake pipes on the outside of your house and keep them clear of snow, every couple of hours during heavy snowfall. If snow blocks them, the furnace’s pressure switch will shut it down for safety. Clear the pipes gently by hand or with a broom, then reset the thermostat. Call a technician if it doesn’t restart.
Do I need a carbon monoxide alarm if I have a gas furnace?
Yes. In Ontario, homes with a fuel-burning appliance such as a gas furnace, water heater or fireplace, or with an attached garage, must have carbon monoxide alarms next to sleeping areas. Test them monthly, replace batteries as recommended, and replace the alarm by its end-of-life date. If it sounds, get everyone outside and call 911.
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