What should I do to prepare my Toronto home ductwork for the heating season?

Preparing your ductwork for the heating season should happen in September or early October — before the first cold night catches you off guard — and involves a systematic check of your furnace filter, registers, accessible duct connections, and ventilation components. These steps take a couple of hours for a homeowner and can prevent comfort problems, efficiency losses, and emergency repair calls during the heating season.

Start with your furnace filter. This is the single most impactful maintenance task for your entire duct system. A dirty filter restricts airflow, forces the blower to work harder, increases static pressure throughout the ductwork, and reduces heating efficiency. Replace disposable filters or clean washable filters before the heating season begins, then check monthly through the winter. A standard 1-inch filter should be replaced every 1-3 months depending on household conditions — homes with pets, renovation dust, or multiple occupants need more frequent changes. If you have a 4-inch or 5-inch media filter, it typically lasts 6-12 months but should still be inspected at the start of heating season. Filters cost $5-$30 depending on type and MERV rating.

Walk through every room and check all supply and return registers. Open every register fully — do not close registers in unused rooms, as this increases static pressure and can damage your blower motor and cause duct leaks at joints. Remove registers and vacuum the boot cavities where dust, pet hair, small objects, and debris accumulate over the summer. Clean the register grilles with soap and water. While you are at each register, turn the furnace fan on and hold a tissue near the grille — it should blow outward steadily at supply registers and pull inward at return registers. Weak or absent airflow at a register that previously worked indicates a disconnected duct, a crushed flex run, or a closed damper.

Inspect accessible ductwork in the basement. Look for obvious disconnections at joints, torn or hanging insulation, rust or corrosion on galvanized steel ducts, and evidence of water staining or mould on duct exteriors. Listen for air leaks while the system runs — a hissing sound at a joint means air is escaping before reaching the register. You can seal accessible joints yourself with duct mastic for $15-$30 in materials. Pay special attention to the connections at the supply and return plenums where ducts meet the furnace — these high-pressure points are common leak locations.

Check your HRV or ERV if you have one. Clean or replace the filters, wash the heat exchange core if the manufacturer recommends it (most do, annually), and clear the condensate drain. An HRV or ERV with clogged filters or a blocked drain will not ventilate effectively and can develop condensation problems during the heating season.

Clear the area around your furnace — remove any stored items within 3 feet to ensure adequate combustion air supply and safe operation. If you have a conventional gas furnace, check that the combustion air intake is clear of debris and not blocked by snow fencing, landscaping, or storage. Schedule a professional furnace tune-up annually — this is separate from ductwork maintenance but critical for safe, efficient heating. A qualified HVAC technician will check gas pressures, heat exchanger integrity, and airflow — issues that affect how your ductwork performs all winter.