Furnace Carbon Monoxide Risk — Prevention and Detection
Published: July 23, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
How Furnaces Produce CO
Gas furnaces produce carbon monoxide as a byproduct of incomplete combustion. Under normal conditions, the CO is safely vented outside through the flue. CO enters the home when: the heat exchanger is cracked (most common cause), the vent pipe is blocked or disconnected, the burner is not properly adjusted (incomplete combustion), or the chimney or flue is blocked by debris.
Prevention through Maintenance
Annual furnace maintenance includes: combustion analysis (measures CO level in the flue), heat exchanger inspection (visual and camera inspection for cracks), burner adjustment (correct air-to-fuel ratio), and venting inspection (check for blockages, damage, or disconnection). Annual service is the most effective CO prevention measure.
CO Detectors Save Lives
BC law requires CO detectors in all homes with fuel-burning appliances. Install detectors on every floor and outside each sleeping area. Test monthly, replace batteries annually, and replace the entire detector every 5-7 years. If the detector alarms: evacuate immediately, call 911 from outside, do not re-enter until emergency services clears the building.