Carbon monoxide (CO) is an odorless, colorless gas that can be deadly if it accumulates in enclosed spaces. Protecting your home and family from this silent threat requires a reliable carbon monoxide detector. There are many options on the market with different features to keep your household safe. In this article, we’ll explore the options and give guidance on choosing the best one for your home. Richard Trethewey, This Old House’s plumbing and heating expert, discusses carbon monoxide detectors in the video above.
Types of Carbon Monoxide Detectors
In this section, we’ll break down the main types of carbon monoxide detectors that homeowners typically purchase.
Plug-In Detectors
Plug-in carbon monoxide detectors are among the simplest and most affordable options available. These devices plug directly into an electrical outlet and provide continuous protection—as long as they’re connected to power. Here are some key features of plug-in detectors:
- Easy installation with no wiring required
- Often include a battery backup for protection during power outages
- Typically lower cost than other types
Some models feature a digital display showing current CO levels. These detectors should be placed strategically across the home for optimal coverage.
Battery-Powered Detectors
Battery-powered carbon monoxide detectors can be mounted on walls or placed on shelves and operate even during power outages. These are some of the benefits of battery-powered detectors:
- No need for nearby electrical outlets
- Portable and easy to relocate if needed
- Unaffected by power outages
If you choose this type of carbon monoxide detector, periodically check to see if it needs new batteries. Some models combine battery power with plug-in capability for added versatility.
Hardwired Detectors
Hardwired carbon monoxide detectors are permanently connected to your home’s electrical system. These detectors offer several advantages:
- Consistent power supply without relying on batteries
- Often include a battery backup for protection during power outages
- Often interconnected with other detectors for whole-house alert systems
Some hardwired detectors combine CO detection with smoke detection for comprehensive safety. While hardwired detectors typically require professional installation, they provide reliable, long-term protection for your home.
Carbon Monoxide Detector Features
Consider the following features when deciding which carbon monoxide detector is the best fit for your home.
Digital Display
Digital carbon monoxide detectors provide real-time information about CO levels in your home. These models continuously monitor and display current CO concentrations. Some models track long-term exposure. Digital screens are also easy to read.
Voice Alerts
Some advanced carbon monoxide detectors include voice alert systems. This feature can wake you if an emergency arises overnight and can give you instructions on what to do. Many of these systems also tell you exactly which type of danger you’re in (CO, smoke, etc.). Voice alerts are a good choice for households with children or elderly members.
Smart Home Integration
Modern carbon monoxide detectors often offer smart home capabilities, allowing for enhanced monitoring and control. Smart detectors may include the following features:
- Easy access to testing and silencing features through mobile apps
- Integration with other smart home devices for automated responses
- Remote monitoring of CO levels and detector status
- Smartphone notifications when CO is detected
Placement and Installation of Carbon Monoxide Detectors
Avoid installing detectors directly above or beside fuel-burning appliances, and mount detectors at least 15 feet away from cooking or heating appliances. Follow manufacturer instructions for specific height and placement recommendations
Install at least one detector on each level of your home. Place detectors near sleeping areas—ideally outside the bedrooms. In the video, Trethewey emphasizes the importance of having a detector outside sleeping areas to wake occupants if CO levels rise during the night.
For the most comprehensive coverage, we also recommend placing detectors in areas where combustion gases may occur, such as basements or garages. Avoid placing detectors in dead air spaces, such as corners, where air circulation is limited. Make sure each detector is easily accessible for maintenance and testing.
Maintenance and Testing of Carbon Monoxide Detectors
Follow these steps to keep your detectors in top condition:
- Test your detectors monthly using the test button.
- Replace batteries in battery-powered or battery-backup units as recommended by the manufacturer.
- Clean detectors regularly by gently vacuuming or dusting them.
- Replace entire units according to the manufacturer’s guidelines, typically every five to seven years.
- Keep detectors free from paint, stickers, or other coverings that may impair their function.
It’s good practice to keep a log of testing and battery replacement dates. Be mindful of the detector’s expiration date (usually indicated on the unit). Listen for any chirping sounds, which often indicate the need for maintenance.
Understanding CO Levels and Detector Responses
Carbon monoxide detectors are designed to alert you to dangerous levels of CO in your home. Understanding how these devices label and respond to different CO concentrations can help you react appropriately to alarms. Here’s how you can interpret different readings:
- Low levels (below 50 ppm): Most detectors won’t alert you at this level but may display readings on digital models. Prolonged exposure to low levels can still pose health risks.
- Moderate levels (50–100 ppm): Detectors may sound after one to two hours of sustained exposure. These levels can cause symptoms like headaches and dizziness.
- High levels (over 100 ppm): Alarms typically sound within 10–40 minutes of high-level exposure, depending on concentration. High levels are dangerous and require immediate action.
- Extreme levels (over 400 ppm): Extreme levels indicate immediate danger, and alarms should sound within a few minutes. These levels can be life-threatening and require urgent evacuation.
Health Effects of Prolonged Exposure
Even exposure to low levels of carbon monoxide can be harmful over time. Children, the elderly, and those with respiratory conditions are particularly at risk. These are a few symptoms of CO poisoning:
- Chest pain
- Confusion
- Dizziness
- Fatigue
- Headaches
- Nausea
In severe cases, CO poisoning can lead to unconsciousness or death. If you suspect CO poisoning, seek fresh air and medical attention immediately.
Action Steps When Alarms Sound
When a carbon monoxide detector alarms, follow these steps:
- Immediately move to fresh air—outside or by an open door or window.
- Account for all household members.
- Call emergency services and report the alarm.
- Do not re-enter the premises until professionals deem it safe.
By understanding CO levels and appropriate responses, you can act swiftly and effectively to protect your family.