Universal Security Instruments Hardwired 2-in-1 Carbon Monoxide & Natural Gas Smart Alarm with Battery Backup, Model MCN108
€70
Price: $69.99
(as of Jul 27, 2025 18:50:44 UTC – Details)
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2-in-1 alarm provides double the protection with a single installation to protect against carbon monoxide and natural gas
Features a quick activation pull-tab and a front-loading battery drawer for replacement without removing the alarm from the bracket
Bracket mounts to any standard wiring junction box
Suitable for houses, apartments, and mobile homes
Comes with a seven-year limited warranty
Customers say
Customers find the carbon monoxide and natural gas alarm works well, is easy to install, and serves as a perfect replacement. Moreover, the product is well-priced. However, they report issues with battery life, with the device chirping as if it’s dead, and false alarms. Additionally, the lifespan is concerning, with units failing after 20 months of use, and customers express concerns about the product’s quality.
8 reviews for Universal Security Instruments Hardwired 2-in-1 Carbon Monoxide & Natural Gas Smart Alarm with Battery Backup, Model MCN108
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Cynthia Phipps-Jipson –
a good device
I purchased this item because it was the same one that the previous owner had installed in the house, he is a LT fireman, so it must be a good device.
Nater Tater –
Perfect choice
This was a perfect replacement for my CO alarm that was starting to fail due to age. My existing alarm was 11 years old and I ordered this one, which has the added feature of “natural gas alarm.” It was a quick connect and I had swapped them out in under 5 minutes. No wiring changes from the builder-grade alarm originally installed in my home. Just plugged the wires in. Comes with a battery, also!Update: A little over 4 years later and the unit is not working properly. So, for 4 years it was great, then started acting up, now it won’t shut up. Seems like it should last longer than that.
sideliner –
USI MCN108 is faulty
Do not buy this product. My first one came installed in new house and lasted less than 4 years. To obtain warranty you have to pay to ship faulty unit back which costs almost as much as new unit. I replaced with same unit because it would fit prewired receptacle on my ceiling. New unit failed giving false alarm in middle of night. Must get step ladder remove from ceiling and remove battery to stop alarm which is extremely loud. Three months later it gave another false alarm. This time I bounced it off the tile floor to silence it and threw it in the trash. Will probably get electrician to come out and install a different brand as I cant find anything else to fit the hard wired bracket on my ceiling.
R Holding –
Performed as stated and no problem with a quick delivery
This product is as stated and no surprises. It replaced an old and out dated one with no modifications and so far working fine.
Peaches –
Perfect replacement for expired unit
Exactly what I was looking for. I needed to replace an older unit that had reached the end of its service life. This was a similar model that allowed me to use the same mounting plate I use on the expired model. Easy switch.
C. A. Rake –
Lasted almost a year before dying
Had a CO detector from USI fail (resulting in calling in the fire dept to check things out), and replaced it with a MCN108. A year later it starts chirping a fault signal, so time to throw that away and get another. I tried blowing dust out, changing battery, etc, but nothing worked. These things just don’t seem to last long.
Amazon Customer –
Five Stars
Easy to install. Works great so far. Well priced as well.
Don –
Not so sure
This is the second of these the I bought, because the first one failed after about 6 months in service. I purchased the same thing again for ease of replacement, but this will be the last one if it fails early. The seller offered no warranty.