Carbon Monoxide Alarms: How to Choose and Place Them Before Winter Storms

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Why a CO alarm belongs in every winter prep plan

Carbon monoxide is colorless and odorless, which means a working alarm is often the only warning a household gets. According to the CDC, more than 400 Americans die every year from unintentional CO poisoning that is not linked to a fire, more than 100,000 visit an emergency department, and more than 14,000 are hospitalized. Symptoms such as headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion can feel a lot like the flu, and people who are asleep or who have been drinking can be overcome before they notice anything is wrong. Infants, older adults, and people with chronic heart disease, anemia or breathing problems are more likely to get sick.

Winter brings more of the usual CO sources into play: furnaces and wood stoves run longer, fireplaces get used more, and power outages push people toward generators and other fuel-burning equipment. A CO alarm will not fix a dangerous setup on its own, but paired with a few basic habits it is one of the simplest, most useful things you can add to a winter storm plan. For the broader outage plan, see our guides on how to survive a winter power outage and what to do first during a blackout.

What to look for in a carbon monoxide alarm

Not every CO alarm is built the same way, and the differences matter when you are comparing options. Here is what the U.S. Consumer Product Safety Commission (CPSC) and other agencies suggest checking before you buy:

• Safety standard: Look for an alarm that meets the current UL 2034 standard. The CPSC generator safety alert also lists IAS 6-96 and CSA 6.19.01. The standard should be printed on the packaging or the unit.
• Power type: Battery-operated, plug-in or hardwired. The CPSC notes that plug-in and hardwired alarms should have a battery backup so they keep working during a power outage, which is exactly when CO risk often rises.
• Interconnection: The CPSC considers interconnected alarms best: when one unit sounds, they all sound, so you hear a warning no matter which room you are in.
• Display: Some alarms show a digital CO reading in addition to sounding an alarm. It is not required, but it can be handy.
• Combination smoke/CO units: Some devices detect both smoke and carbon monoxide. Check the label carefully: a smoke-only alarm does not detect CO, and a CO-only alarm does not detect smoke.
• Replacement age: CO alarms do not last forever. The CPSC says each alarm has a recommended replacement age, listed in the product literature, so check it before you buy and note it on the unit.

Battery, plug-in or hardwired: which power type fits your home

There is no single best power type for every home. The right choice depends on your house, your budget and whether you already have hardwired smoke alarms.

Because outages are when generators and backup heaters come out, the CDC specifically recommends battery-operated or battery back-up CO detectors near every sleeping area. Whatever type you pick, confirm the battery backup on the box rather than assuming it.

Where to put CO alarms (and where not to)

• Install an alarm in a central spot on every level of the home, including the basement, per the EPA.
• Put one near or outside each sleeping area, since CO can overcome people before they wake up.
• Add an alarm near the door to an attached garage and in any room above a garage (EPA).
• Keep alarms away from heating vents and from furniture or drapes that could cover them, per the CPSC.
• The CPSC does not recommend placing CO alarms in kitchens or directly above fuel-burning appliances.
• The EPA suggests keeping alarms at least 15 feet from fuel-burning appliances. Kidde’s placement guide suggests extra alarms 5 to 20 feet from sources like a furnace. When guidance varies, follow the instructions for your specific alarm.
• Avoid dead-air spaces and spots right next to a window or door (Kidde).

Testing, batteries and replacement

• Test monthly. The EPA recommends testing CO alarms monthly, and the CPSC generator alert says to test batteries monthly. Note that the test button checks the alarm’s circuitry, not the accuracy of the sensor (CPSC).
• Check batteries at the clock change. The CDC recommends checking batteries each spring and fall when the clocks change, an easy habit to pair with smoke alarm checks.
• Replace on schedule. The CDC says to replace detectors following the manufacturer’s instructions or every 5 years. Your alarm’s manual is the final word for that model.
• Know your alarm’s signals. Read the manual so you can tell a low-battery or end-of-life signal apart from a true CO alarm.

Generators, heaters and outages: the habits that matter as much as the alarm

• Generators: The CDC says to run generators outdoors, more than 20 feet from windows, doors and vents. The CPSC portable generator safety alert warns never to run one inside a home, garage, crawlspace or shed, because indoor use can kill in minutes, and never to backfeed power into a wall outlet.
• Heating systems: Have furnaces and other heating systems serviced every year, as the CDC recommends.
• Space heaters: Per CDC winter storm guidance, keep space heaters at least 3 feet from drapes, furniture and bedding.
• Fireplaces and charcoal: Use a fireplace only if it is properly vented, and never burn charcoal indoors.
• Vehicles: Never run a car in an attached garage (CDC).
• Cooking appliances: Never use a gas range, oven or clothes dryer to heat your home (CPSC).
• Grills and camp stoves: Never use them inside the home, in a basement or garage, or near windows (CDC).

What to do if your CO alarm goes off

The CPSC guidance is simple and worth going over with your family before an emergency:

• Never ignore the alarm.
• Get everyone outside to fresh air immediately.
• Call 911 or your fire department.
• Do not go back inside until emergency responders say it is safe.

Gear to consider

• A UL 2034 carbon monoxide alarm with battery backup for each level of your home, plus coverage near sleeping areas and the attached garage.
• Spare batteries for your alarms, stored where you can find them in the dark.
• A battery-powered lantern or flashlight, which the CDC recommends over candles during an outage.

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FAQ

Do I need a CO alarm if my home is all-electric?
Yes, if you have an attached garage, ever run a generator, or might use any fuel-burning heater or stove during an outage.

How many CO alarms do I need?
At minimum, one on each level of the home, including the basement, and one outside each sleeping area, per EPA and CPSC guidance.

How long do CO alarms last?
Check your alarm’s manual. The CDC says to replace detectors per the manufacturer’s instructions or every 5 years.

Can a smoke alarm detect carbon monoxide?
Only if it is labeled as a combination smoke and CO alarm. Check the packaging or label before assuming you are covered.