Are Carbon Monoxide Detectors Required in Pennsylvania?

Yes. Carbon monoxide detectors are required in Pennsylvania in any home that contains a fossil fuel-burning appliance, a fireplace, or an attached garage. The rule comes from the Carbon Monoxide Alarm Standards Act, known as Act 121 of 2013, and it applies statewide to one- and two-family homes, townhouses up to three stories, and apartments in multifamily buildings. Willfully failing to install or maintain a required alarm is a summary offense carrying a fine of up to $50.¹

Which Homes the Law Covers

Act 121 ties the requirement to the presence of a carbon monoxide source rather than to the age or style of the building. You need an alarm if the home has any of the following:

A fossil fuel-burning heater or appliance, such as a furnace, water heater, gas stove, or space heater
A fireplace, whether wood-burning or gas, built-in or freestanding
An attached garage, where vehicle exhaust can migrate into living space

The statute defines “fossil fuel” broadly to include coal, kerosene, oil, wood, fuel gases, and other petroleum or hydrocarbon products that produce carbon monoxide when burned.¹ Wood is on that list, so a home heated by a wood stove is covered even without any gas service.

The covered “residential buildings” include detached one- and two-family dwellings, along with multiple single-family dwellings no more than three stories tall with separate means of egress. Apartments in multifamily buildings fall under a separate provision of the same act.¹

All-Electric Homes Are Exempt

If your home has no fuel-burning appliance, no fireplace, and no attached garage, Act 121 does not require you to install a carbon monoxide alarm. An all-electric house with a detached garage or no garage has none of the triggers the law targets. Many safety experts still recommend installing one anyway, since a portable generator or a future swap to a gas appliance can introduce a CO source that was not there before.

Where Alarms Have to Be Installed

The statute requires alarms in two locations: centrally located in the vicinity of the bedrooms, and in the vicinity of the fuel-burning heater or fireplace itself.¹ A single alarm in a hallway serving a cluster of bedrooms can satisfy the sleeping-area requirement for those rooms. The EPA likewise recommends an alarm in the hallway near every separate sleeping area.²

A home with bedrooms on more than one floor, or in separate wings, needs an alarm near each sleeping area. The second required alarm, near the furnace, boiler, or fireplace, catches CO at the source before it drifts into the rest of the house.

What Counts as an Approved Alarm

Not every device on the shelf qualifies. Act 121 defines an “approved carbon monoxide alarm” as one that complies with the ANSI/UL 2034 standard for single and multiple station carbon monoxide alarms, or the ANSI/UL 2075 standard for gas and vapor detectors and sensors.¹ Look for the certification mark on the packaging or the back of the unit. Most name-brand alarms sold at major retailers carry the UL 2034 listing.

Combination smoke and CO alarms are permitted as long as the device meets both the applicable CO standard and the corresponding smoke alarm standard and produces distinct sounds for smoke and carbon monoxide. Battery-only units, plug-in models with battery backup, and hardwired alarms are all acceptable power configurations. Hardwired units with battery backup keep working during a power outage, which is when portable generators and space heaters, two common CO sources, come into use.

Rental Properties: Who Is Responsible

The division of duties in a rental shifts depending on whether the unit is occupied.

The Landlord’s Duties

Before a new tenant moves into a multifamily rental unit with a CO source, the owner has to install an approved, working alarm in the required locations, replace any alarm that was stolen, removed, or disabled during the prior tenancy, and make sure the batteries work at the start of the new occupancy.³ Those three obligations are the full extent of what Act 121 requires from the landlord at move-in.

While the unit is occupied, the statute explicitly relieves the owner of maintenance, repair, and battery replacement responsibility. That duty returns to the landlord when the unit becomes vacant again.³

The Tenant’s Duties

Once you take possession of a rental unit with an installed CO alarm, the law puts ongoing responsibility on you. Tenants must:

Keep the alarm in good working order
Test it regularly
Replace batteries as needed
Replace any alarm that is stolen, removed, or stops working during the tenancy
Notify the landlord or their agent in writing of any problems with the alarm

The written notice to the landlord is the only formal communication the statute requires, and it runs from tenant to owner.³ Act 121 does not require landlords to hand out written maintenance instructions, and it does not set a deadline for a landlord to respond to a tenant’s repair request. Those terms sometimes appear in a lease or a local ordinance, but they are not in the statute.

When to Replace an Older Alarm

Carbon monoxide alarms do not last forever. The sensor inside degrades, and an expired unit can fail to detect dangerous CO levels even with the green power light still on. The National Fire Protection Association recommends replacement every seven to ten years, depending on the model.⁴

Check the manufacture date printed on the back or side of the alarm. If the label has worn off, replace the unit. Most alarms also use a distinct end-of-life chirp, different from the low-battery beep, to signal that the device has expired.

Penalty for Not Complying

Enforcement under Act 121 applies to willful violations. Knowingly failing to install or maintain a required carbon monoxide alarm is a summary offense punishable by a fine of up to $50.¹ The regulatory fine is modest, but the exposure does not end there. If someone is injured or killed by carbon monoxide in a home where the required alarm was missing or disabled, a court could treat that violation as evidence of negligence in a civil case.

Insurance adds another layer. Many homeowner and landlord policies condition coverage on compliance with local safety codes. An insurer that finds a required CO alarm was missing or inoperative at the time of a CO incident may reduce or contest a claim. Some carriers also offer small premium discounts for homes equipped with working CO alarms.

1
Pennsylvania General Assembly. Pennsylvania Act 2013-121 – Carbon Monoxide Alarm Standards Act
2
Environmental Protection Agency. What About Carbon Monoxide Detectors
3
Pennsylvania General Assembly. Pennsylvania Code 35 P.S. 7225 – Carbon Monoxide Alarm Requirements in Rental Properties
4
Kidde. When Should I Replace My Carbon Monoxide Alarm