Use this simple safety checklist whenever you notice a furnace burning smell. Is it dusty and fading? That's usually normal. Does it smell like plastic, wiring or rubber? Turn the furnace off. Do you see smoke, or is the smell getting stronger? Turn it off and call for help. Smell rotten eggs? Leave the house and call the gas emergency line from outside. And remember that carbon monoxide has no smell, so every home needs CO alarms. Purcell Heating & Air explains every step.