HVAC maintenance: keeping furnaces, boilers and heat pumps safe and efficient

How often each system needs service

NRCan's Keeping the Heat In ↗ says a qualified service technician should perform annual maintenance and efficiency tune-ups, and that homeowners can do some of the work in between. Intervals by system, from NRCan and Health Canada:

The yearly inspection advice from Health Canada ↗ is about carbon monoxide (CO). Where intervals differ, follow the more frequent one and your manufacturer's instructions.

What a proper tune-up includes

HRAI ↗, the Heating, Refrigeration and Air Conditioning Institute of Canada, says a furnace inspection by a licensed technician should include:

• a safety test for carbon monoxide
• checking the chimney and flue for debris
• cleaning and reinstalling air filters
• checking the thermostat and safety controls, and the gas pilot safety system
• cleaning the motor and fan, and checking blower operation (and the fan belt on older systems)
• cleaning burners and setting them for proper combustion and ignition
• checking the gas piping to the furnace

For heat pumps, the US Department of Energy ↗ adds measuring the refrigerant charge, checking for refrigerant leaks, measuring airflow, sealing duct leaks, tightening electrical connections, lubricating motors, and confirming that heating and cooling can't run at the same time. CMHC ↗ notes that a properly tuned combustion appliance rarely produces carbon monoxide, and suggests asking for furnace cycles of six minutes or longer to limit spillage at start-up.

To find a contractor, HRAI's Contractor Locator ↗ lists members, who must carry insurance and valid trade certificates and licences, and agree to HRAI's code of ethics.

Signs of trouble and carbon monoxide safety

• Soot or staining around a furnace, boiler or water heater, or melted plastic fittings on top of a tank water heater: signs of back-puffing, according to NRCan.
• Unusual odours or hot, muggy air around a fuel-burning appliance.
• Frequent headaches, skin or throat irritation or nausea, or unexplained smoke or CO alarms.
• Exhaust vents blocked by ice or snow; Health Canada says to check them during and after snowstorms.
• Rooms that never heat evenly, which NRCan links to undersized or leaky ducts and poorly placed return grilles.

Health Canada lists early CO symptoms as tiredness, headaches, flu-like symptoms and shortness of breath; higher levels bring dizziness, chest pain, poor vision and difficulty thinking (symptoms ↗). If a CO alarm sounds, leave the home immediately, don't try to find the source, call 9-1-1 from outside and return only after a professional has fixed the problem.

The National Building Code 2025 ↗ requires CO alarms in homes with a fuel-burning appliance or an attached garage, certified to CSA 6.19 and placed inside each bedroom or within 5 m of each bedroom door. Health Canada says the most important spot is the hallway outside sleeping areas; test alarms regularly and replace them by the manufacturer's expiry date. See our CO alarm guide.

What an energy advisor checks

• Combustion safety: a combustion safety and spillage test checks whether exhaust fans can depressurize the house enough to pull flue gases back in. HRAI certifies technicians in depressurization testing (DTRS).
• Carbon monoxide: a CO alarm check confirms your alarms meet the requirements above.
• Ducts: duct leakage and airflow testing pressure-tests the ductwork and measures airflow at each register.
• Sizing before replacement: NRCan notes that a house with less heat loss after retrofits needs smaller equipment, and that oversizing causes short cycling. Its heat pump guide ↗ recommends sizing to CSA F280; see our room-by-room heat loss calculation.

Maintenance and fixes, from simplest to biggest

Filters. NRCan says to change or clean forced-air filters every three months or as they become loaded; Hydro-Québec ↗ suggests checking heat pump filters monthly during heavy use. On MERV, the rating printed on the filter, CMHC ↗ says a higher number means better filtration, but some higher-MERV filters reduce airflow through the furnace and affect its performance, so ask your technician before upgrading.

Heat pumps and air conditioners. In cold weather an air-source heat pump periodically runs a defrost cycle to melt frost off its outdoor coil; that is normal. NRCan puts its service life at 15 to 20 years (20 to 25 for ground-source). Air conditioners lose efficiency when the indoor coil is dirty, the outdoor condenser is blocked or the refrigerant runs low.

Mistakes to avoid

• Sealing ducts with standard vinyl duct tape. NRCan says its adhesive dries out over time and the tape falls off.
• Paying for duct cleaning to fix air quality or bills. CMHC ↗ and US EPA research found little or no difference in airborne particles or airflow after cleaning, and NRCan says it generally has little effect. CMHC also advises declining offers to spray or “fog” ducts with biocides.
• Upgrading to a high-MERV filter without checking. Some restrict airflow through the furnace.
• Ignoring an alarm, or hunting for the source. Leave first and call from outside.
• Running fuel-burning equipment indoors. Health Canada says never to run a generator indoors or idle a vehicle in the garage, even with the door open.
• Blocking airflow. NRCan warns that furniture or carpeting over vents and registers can shorten equipment life and reduce efficiency.

Rebates and next steps

Rebates for heating equipment and duct work vary by province and change often. Check current offers in our rebate program tracker, estimate whether replacing equipment pays off with the upgrade payback calculator, and use the home energy planner to line up maintenance, air sealing and any equipment change in the right order.