Search Main Index Sub-Section 1. Each year almost 1,500 people die due to accidental carbon monoxide exposure, and an additional 10,000 seek medical attention. Carbon monoxide can escape from any fuel-burning appliance, furnace, water heater, fireplace wood stove, or space heater. It can quickly overcome people in their homes, apartments, recreational vehicles, or even in tents. Tight closing replacement windows and doors, as well as additional insulation can cause similar problems in older homes.
Carbon monoxide can spill from vent connections in poorly maintained or blocked chimneys.
If the flue liner is cracked or deteriorated, CO can seep through the liner and into the house, slowly creeping up to dangerous levels. If an animal's nest or other materials restrict or block the flue, CO will most likely spill back into the house. Improperly sized flues connected to new high-efficiency furnaces and water heaters can also contribute to CO spillage. Many new furnaces and water heaters use the existing chimneys which may be the wrong size to allow the furnace to vent properly. Warming up vehicles in an attached garage, even with the garage door opened, can allow concentrated amounts of CO to enter your home through the car port door or near-by windows.