Most heat loss comes from small gaps around windows, doors, and penetrations rather than the furnace itself, and you can find many of them with a simple hand test.
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Quick answer: Most hidden air leaks are found around window and door frames, electrical outlets, attic hatches, plumbing penetrations, and where the foundation meets the framing. On a windy or cold day, run your hand slowly along these areas and around baseboards to feel for drafts, or use a lit incense stick to see where the smoke wavers. For leaks you can't feel, a blower door test from an energy auditor pinpoints exact locations with more precision.
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It's tempting to blame the furnace when a house feels drafty or bills climb, but in most homes the bigger culprit is air leaking through the building envelope itself. Warm air escapes through small gaps and cracks, and cold outside air is pulled in to replace it, forcing the heating system to work harder just to keep up.
In older Metro Vancouver homes with original wood-frame windows or unfinished crawlspaces, these leaks add up fast. It's rarely one big gap — it's usually a dozen small ones working together.
A licensed CANRO technician can take a look — honest assessment, no pressure.
📞 (604) 359-1081Request a free quoteYou don't need special equipment to find most leaks. On a cold or windy day, close all the windows and doors, then slowly run the back of your hand along window frames, door edges, baseboards, and outlet covers. A sudden change in temperature or a light breeze on your skin usually means air movement.
A lit incense stick or a thin tissue held near suspect areas works well too — smoke or fabric that flutters or bends sideways points to a draft. Check the attic hatch, any recessed pot lights, and where bathroom or kitchen exhaust fans vent through the ceiling, since these are commonly overlooked.
Outside, walk the perimeter of the house and look for gaps where siding meets the foundation, where dryer vents and hose bibs pass through the wall, and around any additions or renovations where new and old construction meet.
A hand test catches the obvious leaks, but it can miss smaller gaps hidden inside walls or behind insulation. A whole-home energy audit that includes a blower door test depressurizes the house and makes even minor leaks easy to detect with a smoke pencil or thermal camera, giving you a prioritized list of what to seal first.
If you've sealed the obvious spots and your home still feels drafty, your energy bills keep climbing, or you notice cold spots that don't line up with anything you can find and fix yourself, it's worth having a technician take a closer look at both the building envelope and how well your heating system and ductwork are performing together. CANRO can also check whether your furnace or ductwork is contributing to comfort problems that get mistaken for air leaks.
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📞 (604) 359-1081Request a free quoteReviewed by the CANRO Heating & Cooling service team — July 07, 2026. Technical Safety BC gas licence LGA0043870 · boiler licence LBP0046450 · Red Seal certified · WorkSafeBC and liability insured · 4.9★ from 85+ Google reviews · serving Metro Vancouver since 1999 · (604) 359-1081.
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