If you smell gas near your furnace, don't troubleshoot. Act immediately. Don't touch light switches or your thermostat. Leave the house, then call ATCO Gas's 24-hour emergency line at 1-800-511-3447 or 911 from outside. Sherwood Mechanical's furnace safety guide also explains what to do if your carbon monoxide alarm sounds, or if you hear a loud bang at startup. Share this important furnace safety information with family and neighbours in Sherwood Park this heating season.