First Alert Combination Smoke & Carbon Monoxide Alarm, Battery Operated Detector with Test & Silence Button, SMICO100, 1-Pack

Why I chose the First Alert combo alarm

I needed a simple, dependable way to cover both smoke and carbon monoxide risks in a few trouble spots in my home without running new wire. The First Alert combo alarm (model SMICO100) promised a straightforward, battery-powered install, nuisance-alarm reduction around kitchens, and the basics I consider non-negotiable: a clear test/silence button and an end-of-life alert. After a few weeks of living with it in a hallway off a busy kitchen and outside a bathroom, here’s how it held up.

Setup and installation

Installation is as easy as battery-powered alarms get. The mounting plate includes multiple slots that lined up with one of my old screw patterns, saving me from drilling fresh holes. Hardware is included, the unit locks onto the plate with a firm quarter-turn, and the side-access battery door lets you swap batteries without taking the alarm down. That’s a small but important convenience for long-term maintenance.

A note on power: this model is battery-operated only. It doesn’t have a hardwired 120V harness and it doesn’t interconnect with other alarms (wired or wireless). If you need linked alarms so that all units sound together, this isn’t the one. If you want a standalone device you can mount anywhere in minutes, this hits the brief.

Build and usability

The housing is low-key white plastic—nothing flashy, which is exactly what I want from gear that blends into a ceiling. The status LED is visible without being obnoxious; a quick glance confirms the unit is receiving power, and fault or end-of-life conditions are clearly indicated with chirps and flashes. The test/silence button is large and responsive. Press-and-hold triggers a full self-test; a tap during a nuisance event quiets it for a short period while it keeps sampling the air.

The sounder is properly loud—rated at the typical 85 dB at 10 feet—and it cuts through household noise. It’s shrill, as it should be. In a nighttime test, it was more than enough to wake a heavy sleeper down the hall.

Sensor technology and nuisance behavior

First Alert’s “Precision Detection” marketing essentially points to compliance with the newer industry standards intended to cut down on cooking-related false alarms while still detecting dangerous fire signatures earlier. In practice, the behavior felt well-balanced. Boiling pots, a steamy bathroom down the corridor, and a quick toast cycle didn’t trigger it. Deliberately burning a bit of bread under the broiler did, as it should.

No smoke alarm is completely immune to nuisance triggers near a kitchen. Placement remains crucial: keep it at least 10 feet from appliances and out of direct airflow from vents or fans. I mounted mine just outside the kitchen path of travel and didn’t get the constant “I made toast” alarms that older ionization-only models love to produce. When I did get a whiff of cooking smoke that set it off, the silence button worked as intended and the unit re-armed on its own.

On the carbon monoxide side, the electrochemical sensor is the right choice for residential use: accurate, stable, and low power. Be aware that CO sensors can be cross-sensitive to certain gases—hydrogen from a failing battery in a nearby UPS or sewer gas from a dry trap can occasionally trigger a CO alarm. If you hear the CO pattern and your home’s plumbing traps have run dry (rare, but it happens), refill those traps and ventilate, then investigate further. The alarm itself did not produce any spurious CO alerts in my time with it, but the general caveat stands for any CO detector.

Everyday use and maintenance

Day to day, this is a set-it-and-check-it device. I schedule a monthly test, which takes seconds: press and hold, listen for the loud two-stage pattern (distinct tones for smoke vs. CO), and confirm the LED indications. Vacuuming around the vents every few months helps prevent dust accumulation that can cause erratic behavior in any alarm.

Battery life will depend on environment and test frequency. The included battery got me started, and the low-battery chirp is hard to miss. I replace batteries proactively in fall when I do my seasonal maintenance; the side door reduces that job to a minute. The end-of-life warning is equally important: all smoke/CO sensors have a finite lifespan due to sensor drift and chemical depletion. When this unit reaches that point, it will chirp in a pattern that tells you it’s time to replace the entire alarm—not just the battery. Plan for that; it’s the cost of reliable detection.

Performance impressions

• Smoke responsiveness: Solid. It ignored light steam and minor kitchen haze but reacted quickly to visible smoke during testing with a smoke aerosol and a “burnt toast” scenario.
• CO detection: I couldn’t ethically simulate a CO event at concentration, but the self-test routine and circuitry checks passed, and the electrochemical sensor is the standard for home safety.
• Alarm audibility: Excellent. Easily heard through closed doors.
• False alarms: Minimal with thoughtful placement and normal cooking behavior. The silence feature is effective when you do get a whiff of smoke.
• Reliability: No spurious chirps, no random resets, and the status LED offers easy reassurance.

What I wish were different

• No interconnect: If you’re equipping a larger home, interconnected alarms are a big upgrade. This model doesn’t support it, wired or wireless.
• Battery type not sealed: I appreciate replaceable batteries for cost and waste reasons, but a sealed 10-year option can be appealing for folks who don’t want to think about batteries at all. This is not that.
• Basic design: The look is utilitarian. That’s fine for most spots, but more compact, low-profile designs exist if aesthetics matter.

None of these are deal-breakers in a battery-only, budget-conscious device—but they’re worth noting so you choose the right category of alarm for your home.

Placement tips

• Install one on every level of your home, in each bedroom, and outside sleeping areas.
• Keep smoke/CO combos at least 10 feet from cooking appliances to reduce nuisance alarms.
• Avoid mounting in bathrooms, garages, or overly dusty areas.
• Ceiling placement is ideal; if you must mount on a wall, keep it high and follow the included instructions for distance from corners and ceilings.

Who it’s for

• Renters or homeowners who can’t or don’t want to hardwire alarms.
• People upgrading older, nuisance-prone smoke-only units to modern smoke/CO coverage.
• Small to medium homes where standalone alarms are sufficient and interconnect isn’t essential.
• Landlords looking for cost-effective, easy-to-service units in compliant locations.

If you’re renovating or building new and already have a hardwired network, look at an interconnected model instead so every alarm sounds together during an event.

The bottom line

The First Alert combo alarm gets the fundamentals right: reliable dual-sensor protection, straightforward installation, a useful silence function, and an end-of-life indicator so you don’t forget to replace aging sensors. It’s not fancy, and it’s not interconnected, but it’s consistent, loud, and easy to live with. In my testing and everyday use, it avoided the nuisance behaviors that frustrate families, and it delivered the kind of confidence I want from a device that needs to work once, immediately, without fuss.

Recommendation: I recommend this alarm for anyone who needs simple, battery-powered smoke and CO protection without the complexity or expense of a hardwired network. It’s a practical, dependable option for hallways, bedrooms, and common areas, especially in homes where drilling and wiring aren’t on the table. If whole-home interconnectivity is a must-have, consider a different model, but for standalone coverage, this one is an easy pick.