Carbon Monoxide Detector Buying Guide

Carbon monoxide detector basics

Carbon monoxide detectors measure the presence of carbon monoxide in the air and keep track of how long it is present. The alarm is triggered if carbon monoxide is present at low levels for a long period of time, or at high levels for a short time.

Carbon monoxide detectors use one of three types of technology to sense this poison in your home’s air. While you don’t need a chemistry degree to select a carbon monoxide detector, it is helpful to understand a bit about how they operate when deciding which one to buy.

Metal Oxide Semiconductor (MOS) Carbon Monoxide Detectors

use heated tin oxide sensors. When CO is present, the heated tin oxide reacts with it and causes the alarm to sound.

Biomimetic Carbon Monoxide Detectors

use a gel-coated disc, which darkens and causes the alarm to sound if carbon monoxide is present.

Electrochemical Carbon Monoxide Detectors

use a chemical reaction with carbon monoxide to create an electrical current that sounds the alarm.

Research indicates that the three types of sensors work equally well and all provide adequate protection. All types of carbon monoxide sensors typically last from three to five years, after which the units should be replaced. Most models do not offer the option of only replacing the sensor, so you must purchase and install an entire carbon monoxide detector when the sensor has expired.

When shopping for a carbon monoxide detector, check for sensitivity to low levels of carbon monoxide and make sure it has been UL tested and approved.

Combination detectors

Some models include a smoke detector and a carbon monoxide detector. This makes them convenient, but authorities on home safety point out some drawbacks. Carbon monoxide detector placement is more versatile than that of smoke detectors. For the best fire protection, placement of combination units in your home should be based on smoke detector recommendations. Also, while smoke-only detectors use two types of smoke sensors, combination smoke and carbon dioxide detectors utilize only ionization detectors, so they’re not good at detecting low-flame, smoldering fires. Check out Pronto’s Smoke Detector Buying Guide for more on smoke detectors and how they work.

The advantages of combination detectors are that most run on AC power with battery back-up, tell you whether smoke or carbon monoxide danger is present, and allow multiple detectors in a home to be connected without wiring. These carbon monoxide detectors use radio waves to send a signal picked up by one to all others, alerting you immediately to potential problems before smoke or poison spreads.

Power sources

Carbon monoxide detectors run on batteries or hard-wired AC power. AC units are more reliable, but experts recommend choosing a model with battery backup. During power outages, people tend to use carbon monoxide-producing devices, such as fireplaces, generators and space heaters). If one of these appliances begins to emit carbon monoxide while your plug-in carbon monoxide detector is out of commission, you won’t know there’s a problem. Factor in the price of professional installation when comparing carbon monoxide detector costs.

Battery-operated carbon monoxide detectors can be installed anywhere in the home. The optimal placement for carbon monoxide detectors is five to six feet above the floor, which is higher than most AC outlets. As with any battery-operated appliance, it is crucial to replace batteries every six months. Choose dates that you’ll remember, such as daylight savings time or family members’ birthdays.

A carbon monoxide detector should have a test button so you can make sure it is in working order. However, the test button only indicates that the power source is active. It does not mean that the carbon monoxide-detecting chemical component is functioning properly.

Placement and quantity

How many detectors you need depends on the size and layout of your home, and what your local ordinances require. Check with your local fire chief or state fire marshal to learn the specific rules that apply to installation.

If laws don’t apply, a good rule of thumb is to have a single carbon monoxide detector within 15 feet of all bedroom doors. For larger homes, make sure that the carbon monoxide detector is loud enough to be heard in all bedrooms.

For added safety, consider installing carbon monoxide detectors outside of rooms with fireplaces, in the basement near heating equipment, in rooms above or adjacent to garages and near the kitchen if you have a gas stove. Carbon monoxide is generated by burning fuels and can gather to toxic levels quickly. Setting up several carbon monoxide detectors that can communicate with each other will provide the greatest measure of protection.

Additional features

Digital readout and memory is a feature found on some carbon monoxide detectors and combination units. It lets you monitor CO levels and possibly determine the source of rising carbon monoxide in your home. A digital display also assures you that the unit is on and working. Higher-end carbon monoxide detectors record CO levels over time, which is useful to emergency personnel who need to determine the severity of a carbon monoxide leak.

Carbon monoxide detectors use an audible alarm signal of at least 85 decibels as the primary indicator of danger. Some models also relay information by LED lights, which may change colors based on the level of carbon monoxide that is present, or simply illuminate to indicate its presence. For combination detectors, look for a voice warning system that announces “fire,” “carbon monoxide” or “low battery” when the alarm sounds, which will let you know exactly what’s happening if you’re awakened in the middle of the night.

Need to know more?

• Carbon Monoxide Sensor Types
  http://en.wikipedia.org/wiki/Carbon_monoxide_detector
• Carbon Monoxide Safety Tips
  http://www.ul.com/consumers/monoxide.html
• Installing Carbon Monoxide Detectors
  http://www.diynetwork.com/diy/lv_safety/article/0,2041,DIY_14130_2268492,00.html