Types Of CO Detectors
Stand-Alone Carbon Monoxide Detectors
These carbon monoxide
detectors work independently. They can be battery operated or plug into an AC
socket (with a battery backup in the event of a power failure). They are the
easiest type to install, but won't trigger other alarms in the home if they
Interconnected Carbon Monoxide Detectors
Experts say that this is
the best type of CO detector as they will form a network of alarms within your
home. The connection can be hard wired or wireless, and the alarms can either
plug into an AC outlet (with battery backup) or be completely battery operated.
The advantage of an interconnected network is that when any one alarm sounds,
they all sound, giving you an early warning of danger in a remote room, or one
that's otherwise currently unoccupied. Wireless interconnected CO detectors are
fairly easy to install, but hardwired ones can be challenging if a wired network
of compatible alarms isn't already in place.
You can also find CO detectors that
are part of a combination alarm that includes a smoke detector. There are
pluses and minuses to these types of alarms, but if you think one is right for
your situations, combination smoke and CO detectors are covered in detail in
our smoke detector report.
Carbon monoxide detectors save lives
Carbon monoxide (CO) is a
potentially deadly, odorless and colorless gas that is estimated to kill
approximately 500 people a year and sicken many others. Often called the
"silent killer," CO is a by-product of incomplete combustion and
comes from malfunctioning appliances, such as gas or oil furnaces, wood burning
stoves, and gas clothes dryers. When these appliances are not adequately
ventilated, or if they malfunction, carbon monoxide can build up in the home to
lethal levels. The list of potential sources of carbon monoxide also includes a
wealth of items that shouldn't be used indoors under any circumstances,
including portable generators and charcoal grills. Unfortunately, people don't
always follow safety instructions and may use these items improperly.
According to MedlinePlus,
a service of the National Institutes of Health, CO is the leading cause of
poisoning in the United States. As noted by the Centers for Disease Control and Prevention (CDC), everyone is at risk from CO poisoning, though
infants, the elderly and those with certain conditions, such as heart disease,
are most at risk. If you are exposed to CO gas, you may notice symptoms such as
"headache, dizziness, weakness, upset stomach, vomiting, chest pain, and
confusion," the CDC notes. If you are asleep, especially if you're
intoxicated, you're chances of dying from CO exposure are greatly increased.
The good news is that CO
poisoning is highly preventable and the CDC's site has a long list of mostly
common-sense steps to take. Those include servicing gas, oil or coal-burning
appliances regularly, and not using items such as charcoal grills and camp
stoves that are intended for outdoor use indoors. At the top of the list, however,
is this advice:
battery-operated or battery back-up CO detector in your home and check or
replace the battery when you change the time on your clocks each spring and
All carbon monoxide
detectors have a finite lifespan with sensors that wear out within five to
seven years. However, the newest detectors come equipped with an end-of-life
timer. When the time is up, the devices essentially self-destruct -- beeping at
a regular interval until replaced. Don't just trust the timer, though. The National Fire Protection Association (NFPA) recommends that you "Test CO alarms
at least once a month; replace them according to the manufacturer's
All of the CO alarms in
this report meet Underwriters Laboratory standards (UL2034) designed to alert
people well before CO exposure becomes life threatening, but also to prevent
nuisance alarms (caused by things such as typical air pollution or normal
short-term emissions from properly operating appliances) that can cause
homeowners to tune out CO alarms, greatly reducing a detector's effectiveness. They
don't respond at all to very low CO levels below 30 parts per million. Once CO
levels reach 30 ppm, they won't sound until after 8 hours of continuous exposure.
At 70 ppm, they won't sound for at least 60 minutes, but must sound after 4
hours. At 150 ppm, there's a 10 minute delay, but the alarm will sound before
50 minutes have passed. Finally, at 400 ppm, there's a brief 4 minute delay,
and the alarm must sound before 15 minutes.
The bottom line, then, is
that if a CO alarm sounds, the situation merits concern and you should respond
immediately. The NFPA says to do the following: "Move to a fresh air
location outdoors or by an open window or door. Make sure everyone inside the
home is accounted for. Call for help from a fresh air location and stay there
until emergency personnel [arrive]."
The best carbon monoxide detectors
Among stand-alone CO alarms, we saw
the best feedback for the (Est. $30). It draws a Recommended rating
from ConsumerReports.org, and over 1,380 mostly positive reviews from users
posting at Amazon.com. The CO615 is AC powered, but no messy wiring job is
required; instead, just plug it into a convenient outlet. While you can simply use
a low-mounted AC outlet, the AC adapter is removable and is equipped with six-foot
extension cord for placement "flexibility." This allows those looking
for the best protection to place the detector higher on the wall (at least five
feet above the floor) per the recommendations of most experts. Two AA batteries
provide backup for continuous monitoring, even when AC power is out.
The CO615 isn't the most feature
packed CO detector, but there are a few nice touches. The LCD display won't
display continuous CO levels, but can show the peak CO levels over the last 24
hours at the touch of a button. The warning chirp if the back-up batteries
become low can be silenced for eight hours. Some sites continue to list the
existence of a feature that lets you silence the battery back-up warning with
any standard IR remote control, but that feature proved to be problematic and
has since been dropped.
Expert testing looks good for the
CO615. It earns the highest ratings at ConsumerReports.org for its ability to
detect high and low levels of CO. Like all CO alarms in this report, it meets
UL2034 standards for its ability to issue warnings that protect life without
subjecting users to nuisance alarms.
User reviews are also highly positive.
We noted some gripes about build quality, particularly a battery door that's
sometimes called flimsy, and a few found the CO detector challenging to use, or
claimed that it arrived defective. However, those are well offset by a majority
that seem mostly-to-completely pleased with the CO alarm. It rates a 4.5-star
rating at Amazon.com.
If you prefer Kidde products, the (Est. $30) is similarly priced, and
similarly well-liked by users. However, in expert testing, the CO615 is judged
to be a step better at detecting low levels of CO (though the Nighthawk is
still very good in that regard), and is said to have a
higher-quality/more-effective display. Still, users at Amazon.com rate the
Kiddie an identical 4.5 stars, and that's based on even more reviews -- over
Like the First Alert, the KN-COPP-3 is
designed to be plugged into an existing outlet, but, again, is equipped with a
removable adapter for mounting higher on a wall or on a tabletop. Most users
are extremely pleased, though we did see some comments claiming that the unit
burns through back up batteries even when plugged in.
For those looking for a competent,
easy-to-install carbon monoxide detector at the lowest possible price, things
don't get much more basic than the (Est. $16). This CO alarm is
battery powered, which gives you all the installation flexibility you might
need -- though again it might be wise to heed expert advice to install it high
above the floor. There's little in the way of features -- no readouts or voice
warnings here -- just a button to silence nuisance alarms and a pair of LEDs to
indicate that the unit is operating or if an alarm is sounding.
User reviews are generally positive,
though complaints about defective units or excessive battery usage are not
unheard of. Still, Amazon.com users rate the carbon monoxide alarm a solid 4.6
stars based on more than 330 reviews. At HomeDepot.com, where this model is
sold under the Code One brand, it earns an equally impressive score of 4.5
stars after more than 230 reviews, with recommendations from 95 percent of
Interconnected alarms can provide an early warning
While users tend to prefer the
simplicity of stand-alone alarms, experts often prefer interconnected ones that
can alert homeowners to issues in areas that are currently unoccupied. Among
interconnected choices, we see good expert feedback for the (Est. $45). It's feature packed and easy to set up and use.
Many interconnected CO alarms require
a messy and expensive hard-wired installation, but the CO511B uses a radio signal
is used to communicate between alarms. It's compatible with other First Alert wireless
alarms, including the (Est. $55 for 2)
photoelectric smoke detector and the (Est. $45) combination CO and smoke detector; both are profiled in our
report on smoke detectors.
The feature list on the CO511B goes
well beyond its radio link, but that's a good place to start. The system
establishes a mesh network, independent of other networks, such as Wi-Fi within
your home. Each alarm acts both as a receiver and a transmitter, allowing the
network to extend further. Security codes and frequency hopping technology establish
stable and secure communications between alarms.
Other features include a voice alert
that includes location information so that you won't be left guessing which
alarm has sounded; up to 11 locations, such as a basement, can be programmed.
Latching technology provides a visual indication of which alarm sounded after
the alert has shut off. It also gives you a visual indication of which unit has
a low-battery condition. The alarm tone sweeps through low frequencies to aid
those with age-related or other hearing loss.
The First Alert CO511B does well in
expert testing by ConsumerReports.org, with top ratings across the board for
detecting high and low CO levels and for the quality of its voice alerts. User
reviews, while not plentiful, are generally positive. Most say that
installation is easy and that communication with other interconnectable First Alert alarms -- smoke, CO or combination, and either battery operated or
hard wired -- work as advertised.
While the First Alert CO511B is a
great choice for homeowners looking to add CO protection with a minimum of muss
and fuss, if you are adding carbon monoxide alarms as part of new construction
or a major remodeling job, you, or your contractor, might prefer a hardwired
unit. The First Alert CO511B is completely battery powered and, while battery
life should be reasonable, the batteries will need to be replaced periodically.
A hard-wired CO alarm should have a battery as well (though not all do) to
provide constant monitoring even during power outages; however, it's only a
back-up, the main power will draw from your home's AC wiring.
Among hardwired interconnected CO
detectors, we saw good feedback for the (Est. $40). It's not been professionally tested, but we found over 140 user
reviews at Amazon.com, and the majority of owners are pleased as it earns a 4.5
Like the First Alert CO511B, the Kidde
KN-COP-IC can be used in a network of compatible Kidde alarms, including smoke
and combination CO and smoke detectors, interconnected via a simple wired
network. Installation is reported as easy as long as walls are down or a
compatible Kidde alarm network is already in place; otherwise you might want to
enlist the aid of an electrician to run the connections between units.
Installation considerations aside, The
KN-COP-IC looks to be a fine unit. It lacks some of the features found in the CO511B,
such as a voice alert, but adds others that the First Alert alarm lacks. Chief
among those is a readout that displays CO levels, updated every 15 seconds. It
also has a peak memory that can recall the highest CO level measured since the
alarm was last reset.
Expert & User Review Sources
While there are a number of sites that
report on CO detectors, the only one we spotted that does current, credible
testing is ConsumerReports.org. Editors there rate each detector on its
ability to respond to both high and low levels of CO, and the quality and
accuracy of the display or, if a feature of the tested alarm, voice message.
Beyond that, we looked to the feedback from owners posting at sites such as Amazon.com, HomeDepot.com, Lowes.com and elsewhere. That feedback is
extremely helpful in assessing things such as ease of installation and
reliability -- including freedom from excessive false alarms.