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Kidde KN-COPP-3 Plug-In Carbon Monoxide Alarm with Digital Display
$41.78
Final price set by Amazon · may vary
The Kidde KN-COPP-3 is an AC plug-in carbon monoxide alarm with a digital display and battery backup, designed for living spaces where continuous outlet-powered operation is preferred. A distinguishing feature is its...
Key Features
- AC plug-in with battery backup for outage protection
- Digital display shows CO concentration in ppm
- Peak level memory — recalls highest CO reading
- 85 dB alarm with visual LED alert
- Test/reset button
- UL 2034 listed
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The Kidde KN-COPP-3 is an AC plug-in carbon monoxide alarm with a digital display and battery backup, designed for living spaces where continuous outlet-powered operation is preferred. A distinguishing feature is its peak level memory function, which retains the highest CO concentration recorded since the last reset — useful for investigating intermittent CO events that may have occurred while the space was unoccupied.
Read the full Kidde KN-COPP-3 Plug-In Carbon Monoxide Alarm with Digital Display review →
Read the full Kidde KN-COPP-3 Plug-In Carbon Monoxide Alarm with Digital Display review →
Construction and Design
The KN-COPP-3 plugs directly into a standard 120V wall outlet. Battery backup maintains CO detection during power interruptions, switching automatically without interruption. The digital display shows current CO concentration in parts per million. The peak level memory function records the highest concentration observed, accessible by button press even after the CO source has cleared — an important diagnostic capability when investigating the cause of a prior alarm event. The test/reset button allows occupants to confirm alarm function and clear memory readings.
Detection Performance
Detection is electrochemical and meets UL 2034 alarm thresholds. The digital display allows occupants to observe CO build-up in progress and to review historical peak concentrations after an event. The 85 dB alarm is accompanied by a red LED visual indicator. Peak level memory is particularly valuable in residential settings where CO events may be brief and difficult to trace — a malfunctioning gas appliance or garage vehicle may generate CO spikes that dissipate before occupants investigate. The recorded peak concentration helps guide maintenance decisions.
Strengths
- Peak level memory records the highest CO concentration since last reset — aids event investigation
- Digital display provides real-time CO concentration readout
- AC-powered operation with battery backup for uninterrupted protection
- Test/reset function confirms alarm operation and clears memory
- UL 2034 listed for residential compliance
Limitations
- Outlet location determines placement — rooms without accessible outlets require battery models
- No low-level CO alerts for sub-threshold concentrations
- No Wi-Fi connectivity for remote monitoring
Recommended Applications
The KN-COPP-3 is particularly suited for living rooms, hallways, and spaces adjacent to gas appliances or attached garages where CO events may be intermittent and the peak memory function provides investigative value. It is appropriate for households that want CO concentration visibility and event logging in a plug-in form factor.
Verdict
The Kidde KN-COPP-3 offers meaningful diagnostic capability beyond basic alarm-only CO detectors through its peak level memory function. For households that want to understand what CO concentrations occurred — not just whether an alarm activated — it is a practical and informative choice in the Kidde plug-in lineup.
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What to check before you buy
- UL 2034 listing
- Residential CO alarms in the US are listed to UL 2034. Industrial CO monitoring is a different class of instrument with different alarm thresholds.
- Alarms expire
- CO sensors have a finite life - commonly 7 to 10 years from manufacture. Many units now sound an end-of-life chirp and cannot be reset.
- Placement
- CO mixes with air rather than layering at the ceiling like smoke, so alarms go on every level and outside sleeping areas. Keep them away from fuel-burning appliances and vents to reduce nuisance alarms.
- Digital display
- A display showing parts per million lets you distinguish a low-level chronic leak from a spike, which matters when talking to responders.
How it compares to other carbon monoxide alarms we review
| Product | List price |
|---|---|
| Kidde KN-COPP-3 Plug-In Carbon Monoxide Alarm with Digital Display (this page) | $41.78 |
| Kidde COB Battery-Powered Carbon Monoxide Alarm | $26.97 |
| Kidde COP Plug-In Carbon Monoxide Alarm with Battery Backup | $34.97 |
| Kidde COBD Carbon Monoxide Alarm, Portable AA with Digital Display | $31.97 |
| Kidde COPD plug-in carbon monoxide alarm | $43.97 |
| Kidde COB10 Carbon Monoxide Alarm, 10-Year Battery, LED Alarm-Only | $45.97 |
| Kidde COBD10 Carbon Monoxide Alarm, 10-Year Battery with Digital Display | $52.97 |
List prices recorded when this page was last updated; Amazon pricing moves frequently, so check the live listing. Browse the full carbon monoxide alarms range.
Frequently asked questions
Where should CO alarms be installed?
On every level of the home and outside each sleeping area. Because CO mixes fairly evenly with air, height placement is less critical than it is for smoke alarms - follow the manufacturer instructions.
How long does a CO alarm last?
The electrochemical sensor has a limited life, commonly 7 to 10 years from the date of manufacture. Most modern units chirp at end of life and must be replaced, not reset.
What CO level is dangerous?
UL 2034 alarms are designed to respond to rising concentration over time, sounding faster at higher levels. Any alarm should be treated as real: get everyone outside and call emergency services.
Is a CO alarm the same as a smoke alarm?
No. They detect entirely different hazards. Combination units exist, but a smoke alarm alone offers no protection against carbon monoxide.
Why does my CO alarm chirp?
A single periodic chirp is usually low battery or end of sensor life; a repeating alarm pattern is a CO event. Check the manual for the specific pattern before assuming it is a battery.
Where do the specifications on this page come from?
They are taken from the manufacturer's published listing. WC Safety does not laboratory-test products, and nothing is claimed here that the manufacturer does not state.
Does WC Safety sell this product?
No. WC Safety is an independent review site and an Amazon Associate. Purchases happen on Amazon, and we earn a commission on qualifying purchases at no extra cost to you.
Brand / Vendor
Kidde
Model / SKU
KN-COPP-3
Product Type
Carbon Monoxide Alarm
Price
$41.78 (Amazon)
Rating
4.86 / 5 — 7 reviews
Availability
Check current availability on Amazon
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Verified Buyer Reviews
Customer Reviews
★★★★★4.7 / 5· 27,225 ratings on Amazon
★★★★★
It does the job.
I needed this for a rental property that we are selling. It provides both battery backup as well as plug in power. It is easy to operate, inexpensive and does the job.
Verified Purchaser · April 1, 2 · ✓ Amazon Verified Purchase
★★★★★
Quality CO detector. Worthwhile investment.
Quality Kidde brand CO detector. I replaced my original one with this identical one after 10 years of service, when it finally beeped and showed "END" in the display, which renders it useless, which is by design.Ironically, I never had any CO issues or alerts, until about a few months before its 10th anniversary in service.My home's natural gas boiler was over 25 years old, and begin leaking CO from incomplete combustion issues. This Kidde CO detector audibly alerted me and displayed the current CO level as well as the maximum CO level that it had recorded.Very simple to use and displays basic, yet useful information. I was able to open the windows and ventilate my house to prevent the excess CO buildup from harming us, thanks to this CO detectors audible & visual alerts.Hope they're still making this model 10 years from now, when I will need another one, or if I decide to move and want to purchase a new one. It's certainly not the cheapest CO unit on the market, but it's a good value for the money.Oh, it plugs directly into any standard 110-volt power outlet and it has a 9-volt battery backup, battery included. Although they recommend you replace the 9V backup battery every few years, I never replaced mine, and it was still almost as good as the day it was installed.My Kidde CO detector is plugged into an outlet in our upstairs hallway just outside of our bedroom. Fortunately, it also fit perfectly next to (below) my plug-in doorbell, which was a huge plus!I'm planning on installing one in the basement, near the gas boiler as well. Should have done that years ago, as we would have likely received an earlier "heads-up" that there was a combustion problem with the boiler.One last note: You can remote wall-mount this unit also. Cool feature!If you look at the last picture that I posted with this review, you can see that when the rear access cover is removed to access the backup battery, there is extra cord stored on the opposite side of the battery.The connected main power source plug can be easily removed and relocated/extended, via the corded connection, in order to have the CO detector located somewhere other than directly plugged into the power source.There is also a handy little clear plastic packet included, containing two wood/mounting screws and two wall mount plastic expanding inserts. (Not shown in picture.)Just can't say enough good stuff about this unit. Very pleased with it!
Verified Purchaser · April 28, · ✓ Amazon Verified Purchase
★★★★★
Reliable, Easy to Use, and Gives Peace of Mind 🏠⚠️
I purchased the Kidde Carbon Monoxide Detector for my home, and it has been excellent. The plug-in design with a 9-volt battery backup is very convenient, ensuring continuous protection even during power outages. The digital LED display clearly shows CO levels, which is helpful for peace of mind.Installation was straightforward—just plug it in and insert the battery. The alarm is loud and responsive, and the unit has a solid, durable feel. I also like the compact design, which fits nicely on any wall without being obtrusive.This detector gives me confidence that my family is safe from carbon monoxide, and it’s reassuring to know it’s reliable and easy to maintain.Simple to use, highly dependable, and a must-have for every home.
Verified Purchaser · November 3 · ✓ Amazon Verified Purchase
★★★★☆
Bought 2 as replacements for my Mom's old similar units
My mom installed 2 of these in her house 7 years ago. They both failed and started going off within 2 days of each other. Might have been just a dead battery. I don't know. She called me and said they needed replaced so I got 2 of the current model and installed them for her.I like that these units have a digital readout feature that allows you to pull up not only the current CO level but also the highest level since the last reset. As someone who works around fuel burning appliances as part of my job, I know that CO levels in a structure can vary, and it is important to know not only what the reading is right now, also to know how high the reading has been previously as CO levels can change as appliances or vehicles run, doors or windows open, etc. Even a high quality handheld unit that the fire department or gas company uses to investigate CO complaints is limited because it only knows what the CO level is right at the moment of the test. Meanwhile, this inexpensive digital CO detector cannot only tell you what the level is right now, but also the highest level it has noted...which is an important data point.I also like the way these units can be plugged/mounted directly to an outlet, or you can extend the plug from the unit and mount it a few feet away (perhaps above) the plug to get it into a better sampling position.I gave this unit 4 stars which is the highest rating I would give any of the readily available home CO detectors. Why not 5? Well, they still have a limited service life (like 7 years), and it would be nice if when they fail they would have a different alarm or some very clear indication that the reason it is going off is it has failed, not because it has detected CO. In my 83 year old mother's case, she had the police out there in the middle of the night because her old detector had gone off...and that is very common. When these units fail, it shouldn't initiate a call to 911. They need to make it much more obvious to the homeowner that the unit needs replaced, but there is no reason to call emergency services.
Verified Purchaser · May 19, 20 · ✓ Amazon Verified Purchase
★★★★★
Remember to replace every 10 years
Bought as a replacement for detector that met its 10 year lifespan. Easy to install by just plugging it in to a wall outlet. Appreciate that it comes with a 9-volt backup battery. A potential lifesaver that functions reliably in the background.
Verified Purchaser · March 3, 2 · ✓ Amazon Verified Purchase
★★★★★
Big improvement 🏆
Upon recommendation for ability, and the fact our current CO detector is pushing seven during renovations. It attaches to the ceiling. Figured replacement early based on quality of function for new device and huge savings to buy two as singles if worth it. As vintage ceiling tile are being installed and this device is flexible as to where it sets up. Can be plugged in with the back up battery or wall mounted with battery alone.Although it’s a bit large has a keen sense of detection. There’s no price or device size that matters with safety. But if ya can score a discount kudos.No matter what detector you buy make sure it has a digital read on how much CO2 is invading when it does.To know what’s safe … 0 😁 all seriousness, under 30. The booklet explains the levels. How the device will function in a warning situation. Symptoms o look out for. How long it’ll take to read CO2 depending on how severe it is.It’s recommended to take one on trips when staying at hotels and this detector is easy to set up anywhere. The two pronged action is helpful since this vintage house has a mix of two and three. But for a trip the 9 volt battery is good to go.For RVers this is a must have. Even in a van camping. Better to be safe than sorry.Tip: Write the date of install in permanent marker on the face. This way no need to remember.Tip 2: Same with smoke and fire detectors. For those , what I do is write the yr and month the battery is changed every time. Thin permanent marker should leave plenty of room.Unless hardwired and in ten you just emplacements it. Still, add the date of install. Same with fire extinguishers. Doesn’t hurt to have the fire department inspect it periodically.I know people who’ve lost their hem to fire. Not fun. I know people, like myself, a CO detector got us outta the house.What I like about this detector is the directions have great specifics for set up to avoid false positives and a freak out. Yeah, I did. It was scary. Thank goodness the two times it was for real we were safe.Though at that time we didn’t have a level readout. That’s what makes this gem such a peace.Not sure how long the sale is for. But the singles are a great price now. Hope you score a savings, too.Hope I never hear these defectors go off. But I feel save knowing new ones are in place every ten or less years, if your renovating, where to restock 😊
Verified Purchaser · February 7 · ✓ Amazon Verified Purchase
★★★★★
Highly Rated - indicats low levels
After researching, I bought this detector because it detects much smaller amounts of carbon monoxide than most of the others I looked at.According to industry standards, this brand is recognized as the best on the market. The only draw back; It's so heavy, that it leans away from the wall, where it's plugged into an electrical outlet. To solve this, I put some duct tape behind the unit, to hold it to the outlet cover. Now it stays against the wall, without leaning away from it. A good quality product, and not to obtrusive.
Verified Purchaser · May 19, 20 · ✓ Amazon Verified Purchase
Showing 7 of 27,225 Amazon reviews.
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