Carbon monoxide is a byproduct of burning fuel. Gas ranges, ovens, dryers, water heaters and furnaces all produce some when they run, and when they're working properly and vented correctly, it's carried away safely. Problems start when burners don't burn cleanly, vents get blocked, or fuel-burning equipment is used somewhere it shouldn't be. Because CO has no color or odor, alarms and good habits do the work your senses can't.
If an alarm sounds or you smell gas
Read this part first and remember it:
- CO alarm sounding: get everyone, including pets, outside into fresh air right away. Call 911 from outside. Don't go back in until emergency responders say it's safe.
- Smell of gas (rotten egg odor): don't turn lights or appliances on or off, don't use the garage door opener, and don't light anything. Leave the house, then call SDG&E or 911 from outside.
- Symptoms: headache, dizziness, nausea, weakness or confusion that improves when you leave the house can be signs of CO exposure. Get fresh air and seek medical help.
Alarms
- California law requires CO alarms in homes that have a gas appliance, a fireplace or an attached garage, which covers most San Diego houses.
- Install alarms outside each sleeping area and on every level, following the manufacturer's placement instructions.
- Test monthly with the test button. Replace batteries on the schedule the alarm calls for; many newer alarms have sealed batteries that last the life of the unit.
- CO alarms wear out. Check the date on the back and replace the alarm when it reaches the end of its rated life, typically somewhere between five and ten years.
Kitchen: range and oven
- Burner flames should be mostly blue with a crisp shape. Steady yellow or orange flames, flames that lift off the burner, or heavy soot on pans point to a combustion problem that needs a technician.
- Keep burner caps seated correctly and ports clean.
- Run the range hood fan when cooking, especially with the oven on for a long time.
- Never use the oven or stovetop to heat the house. The CDC's CO prevention guidance specifically warns against using a gas range or oven for heating.
- Don't cover the oven bottom or vents with foil unless the manual says it's OK, since that can affect combustion.
Laundry: gas dryer
- The dryer must vent to the outside, never into the garage, attic or a crawlspace.
- Clean the lint screen every load and the duct regularly. A clogged vent can push exhaust back toward the dryer.
- See the step-by-step dryer vent checks for the full vent routine.
Water heater and furnace
- Look at the vent pipe on top of a gas water heater. It should be firmly connected and sloped upward.
- Keep the area around the water heater and furnace clear of stored items, especially in garages.
- The CDC advises having gas-burning appliances serviced by a qualified technician every year.
Gas connectors and valves
- Every gas appliance should have an accessible shutoff valve. Know where yours are.
- Flexible connectors shouldn't be kinked or stretched. Old uncoated brass connectors should be replaced by a qualified installer.
- After any appliance is moved or replaced, the connection should be leak-tested.
Gas appliances in garages
Garages here often hold the water heater, a gas dryer and sometimes a furnace, alongside cars, gas cans and lawn equipment. Water heaters in California garages are generally installed with the burner raised off the floor and strapped for earthquakes; if yours is sitting directly on the slab or isn't strapped, ask a plumber about it. Keep gasoline and solvents stored well away from any appliance with a pilot light or burner, since fumes are heavier than air and collect at floor level.
Things that should never happen
- Running a generator, grill or camp stove inside the house or in a garage, even with the door open.
- Warming up a car in an attached garage.
- Covering or blocking any appliance vent or flue.
Power outages during Santa Ana events are when generator mistakes happen most. Our wind and outage preparation guide includes generator placement.
When to call for service
A range with yellow flames, a burner that lights with a pop, an oven that smells of gas when lighting, or soot around the oven vent all need a technician. Our gas range repair visits include checking burner flames and ignition, and if the oven itself is the issue, see our oven service page. For any active gas smell, call SDG&E or 911 first, not a repair company.
Put a reminder on your calendar to test the CO alarms the same day each month. It's the cheapest safety step on this page.