Gas Water Heater & Furnace: Carbon Monoxide

A furnace or gas or oil water heater nobody has had serviced in over a year; a rusty, loose or disconnected vent pipe; a heater or furnace closet with stuff piled against it; no CO alarm outside the bedrooms.

CPSC urges a yearly professional inspection of fuel-burning heating systems: furnaces, boilers, water heaters, fireplaces, chimneys, flues and vents. CDC lists furnaces and water heaters among home CO sources, says a blocked chimney can let CO build up indoors, and advises annual servicing by a qualified technician. A blocked or damaged vent can send exhaust back into the house instead of outdoors (our plain-language explanation of back-drafting; CDC's page says a blocked chimney can let CO build up inside). When you book the yearly inspection, ask the technician to check the venting too. Between inspections, the CO alarm is what warns you. If you have a gas dryer, AAP says to vent it outside the home. Keep the space around the heater and furnace clear and follow the manufacturer's clearance instructions (our suggestion; not on the cited pages), and keep gasoline, solvents and paint away from them (see the garage fuel page). CPSC advises CO alarms on every level of the home and outside sleeping areas. CDC: CO symptoms are often described as flu-like (headache, dizziness, nausea), and people who are asleep can die before they have symptoms. The separate CO page for cars, generators and the attached garage is linked below.