Do you need a carbon monoxide detector in an all-electric home?

There are a lot of reasons why some homeowners are switching out gas appliances for electrical. One of the big ones is health and safety: unlike their gas counterparts, electric appliances like ranges and heat pumps don’t produce pollution through combustion. That includes carbon monoxide (CO), which kills at least several hundred people every year in the United States. ¹

CO is a colorless, odorless gas, which means that your home could contain dangerous levels of CO and you might not even know it. It’s for this reason that carbon monoxide detectors are now required in homes. These devices are often combined with smoke and fire detection features, helping to keep you safe from other combustion-related hazards.

If you’re a homeowner who is switching away from gas to electrical appliances, you might wonder if you don’t need to install CO detectors. For all the important value they provide, they do require some maintenance. If they are hardwired, they need a circuit, which is a cost to install. Whether or not they’re hardwired, they still have batteries (as a backup for hardwired devices), which should be changed annually or else they’ll start beeping at you annoyingly. Finally, carbon monoxide and smoke detectors generally should be replaced every 5-10 years.

Does an all-electric home need them? The answer is that it depends: while electric appliances do not produce carbon monoxide, you might still need a CO detector depending on your local or state codes and the configuration of your home.

Not only is carbon monoxide poisoning is a serious issue, but not having required detectors can put you in violation of building codes. That can be a particular problem if you’re renting or selling your home.

For these reasons, this article will dive into how carbon monoxide is produced in homes, how electric appliances avoid these risk, and the local and state codes that dictate whether CO detectors are required where you live.

How is carbon monoxide produced?

Natural gas is mostly methane, which has the chemical formula CH4. When methane is burned perfectly with oxygen (O₂), the byproducts are carbon dioxide and water. Here’s the chemical notation for that reaction:

CH₄ + 2 O₂ → CO₂ + 2 H₂O

While carbon dioxide is also an undesirable pollutant that causes climate change, it’s not toxic until it reaches very high concentrations that wouldn’t normally happen in a home unless something very wrong has happened, such as the exhaust for a furnace or hot water heater getting blocked.

Carbon monoxide is produced when combustion is poor. In formula below, the combustion reaction doesn’t have enough oxygen (only one O₂ instead of two), so carbon monoxide and leftover carbon are the byproduct instead of carbon dioxide.

CH₄ + O₂ → CO + C + H₂O

The leftover carbon atom is soot, which can foul your appliance and restrict the air supply further, making the CO problem even worse.

Sources of carbon monoxide in a home

Any appliance in your home that uses combustion can produce pollution including carbon monoxide. This includes oil and gas furnaces, gas stoves and ovens, oil and gas hot water heaters, fireplaces, pellet stoves, and gas clothes dryers.

As described above, CO is produced when there is insufficient oxygen reaching the flame, resulting in poor combustion. This easy to detect with a gas stove, because you can see the flame directly. A clean burning natural gas flame is blue. If combustion is poor, the flame will be a lower temperature and be yellow or orange. If that’s the case, your stove will need maintenance, such as cleaning the burner heads and caps to ensure that they aren’t clogged.

While easy to spot in a stovetop, combustion problems are much more likely to go undetected with other gas appliances. When was the last time you looked at the open flame in your gas hot water heater or furnace? Annual maintenance helps to prevent issues, but this is a step that many homeowners neglect.

How carbon monoxide can get into a home even when your flues are working correctly

With gas appliances, the exhaust byproducts, including CO, will normally be vented up the flue and exit outdoors. If everything is working correctly, none of that pollution will leak inside, keeping the air quality of your home safe.

However, things don’t always work correctly.

The first potential issue is leaks. If any part of the exhaust system has a leak, pollution can leak into your living spaces. Rust, cracks, and poorly sealed joints in an exhaust flue are some common culprits. This problem is more common if the flue contains bends or uses flexible ducts.

A second and more subtle issue is backdrafting. Backdrafting occurs when negative air pressure is generated in your house, causing air to be pulled inside though any openings in your home. These openings can be obvious places like cracks around doors and windows, but less obvious are exhaust flues and chimneys, including the flues for a hot water heater and gas furnace or the chimney of your gas fireplace. If backdrafting occurs when these appliances are running, the exhaust gases that would normally go outside will instead be pulled inside.

Negative air pressure can be generated when the exhaust fans in your home are turned on, such as bathroom fans and kitchen hoods. The problem with backdrafting is that it is hard to detect. It might occur only periodically, such as when you’re cooking with the exhaust hood on and then one or more bathroom exhaust fans are turned on too.

It’s for these reasons that you need carbon monoxide detectors in your home. Even if you get your gas furnace serviced annually, issues like leaks and backdrafting can still cause CO issues in your home.

Do electric appliances produce carbon monoxide?

Electric appliances like heat pumps and induction stoves produce heat without combustion. Induction stoves use magnetism to heat cookware directly. Heat pumps use the refrigeration cycle to move heat from one place to another, and basic electric appliances like toasters use an electric coil to generate heat directly.

None of these involve combustion. Because of that, electric appliances don’t produce carbon monoxide. There’s other pollutants that gas appliances generate, including nitrogen oxides, which has been linked to asthma ². Electric appliances don’t generate those either. That’s a big advantage, and a reason why many people are switching to electric.

However, one thing to keep in mind is that cooking can still produce smoke, odors, and excess moisture. Cooking a steak will make lots of smoke whether you’re using a gas or induction stove, so you should always use a range hood that exhausts outside. Oil can still catch on fire too, so it’s still important to have smoke detectors.

If electric appliances don’t produce carbon monoxide, do you still need CO detectors in your home?

Because electric appliances don’t produce carbon monoxide, it’s reasonable to think that you might not need CO detectors in your home. This is true in some cases, but quite often you’ll still need them.

First of all, all homes require smoke detectors, and having electric appliances doesn’t change that. As a practical matter, combination smoke and CO detectors don’t cost much more than a high quality smoke detector, so you’re not saving much money by not having CO detection.

In most states, smoke and CO detectors are regulated at the state level, while others allow local governments to set standards. Laws may also differ between single-family and multi-family homes. You can look up a brief description of the laws for your state at the NCSL.org website ³, but you should look up the statute for your state if you want the full details of the law (which can be especially important if you’re a landlord.)

Many states require CO detectors in single-family homes only if there are fossil-fuel burning appliances in the home. This include gas fireplace inserts, which may often be overlooked. If you’re certain that you don’t have any appliances that use combustion, you might not be required to have a CO detector in your home.

However, one big exception that many state laws include is when the house has an attached garage. An internal combustion engine (ICE) car will always produce some carbon monoxide, especially when the car has just been turned on and the catalytic converter is cold. Your car’s catalytic converter will eliminate most of the CO from the exhaust, but it needs to be warm to do this job. Because of this, when you start your car up in the morning, the exhaust will contain a lot of CO.

If your garage is attached to your home, some of that pollution can leak back into your living spaces. It can also backdraft into your home if you have exhaust fans running.

Because of this, if you have an attached garage, you probably are required by law to have a carbon monoxide detector in your home. This is true even if you have an electric vehicle: none of the state laws I reviewed included a CO detector exception for homes with an attached garage that only houses an electric vehicle. And even if you do have an EV, you might sometimes have visitors with an ICE vehicle or you’ll need to rent one sometime. If you have an attached garage you should have a CO detector regardless of the type of vehicle you drive.

Consider your backup power options for blackouts

One major cause of carbon monoxide-related deaths is the use of gas powered-generators. One study focused on New York state showed that long power outages can more than double the rate of CO poisoning among children, who are more vulnerable than the general population. ⁴

This is because gas powered generators are often operated improperly, such as using them indoors or outdoors but near an open window or door that can allow fumes to be drawn indoors.

If you own a gas generator or think that you might invest in one in the future, you should make sure than you have CO detectors installed in your home. An alternative to consider is a solar capable battery backup, which produces zero emissions. While they aren’t a direct replacement for gas generators, they can operate appliances even as large as a refrigerator for several hours. Read my article on solar vs gas generators to learn more.

Where should carbon monoxide detectors be located?

If your local law requires you to have one or more CO detectors in your home, the required location of those detectors is also a matter of law. Some laws only specify that homes need a single carbon monoxide detector in the home without specifying its location, while other laws state that the detector needs to be located near bedrooms. (For example, Minnesota’s law specifies that a CO detector must be within 10 feet of each bedroom.)

Regardless of the minimum requirements in your state or city, it makes sense to have a CO detector located in the utility room where any gas appliance is located. However, forced air ducts can pick up pollution from your utility room and distribute it throughout your home, so having detectors in living spaces is important too.

Again, you should refer to your state or local building/fire codes to determine what is required where you live.

Bottom line: if you have an all-electric home, you may not need a carbon monoxide detector, but you probably should have one anyway

Carbon monoxide is a serious health hazard, which is why most states have laws that require them in homes. However, many of those laws only specify that you need CO detectors if you have a fossil-fuel burning appliance or attached garage. This means that if your all-electric home has none of those, you might not be legally required to have them in your home.

Not having a CO detector can save you some minor cost, but is it worth it? The reality is that you need smoke detectors in your home, and the price difference between a smoke-only and a combination smoke/CO detector isn’t very much. If you don’t want a combination device, a standalone CO detector starts at about $20.

Both smoke and CO detectors need to replaced every so often, so by skipping out on having a CO detector in your home you can save around $20 on every 5-10 refresh cycle, plus the cost of batteries.

Is it worth it? Electric appliances don’t produce carbon monoxide, so an all-electric home without an attached garage in theory doesn’t have any CO sources to worry about.

However, given the small cost, it’s a good idea to have at least one in your home anyway to future-proof your home against future hazards. For example, maybe your all-electric home has a power outage and you temporarily use a gas generator to keep things running. For little cost, having a CO detector in your home will protect you against future hazards that you might not anticipate.

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