Heiman Smart CO Alarm Review: Matter over Thread on a Carbon Monoxide Detector
A FIGARO electrochemical sensor with a ten year battery, alerting every major platform natively through Matter.
The Heiman C1-M is a carbon monoxide alarm that speaks Matter over Thread, which is rare for a life safety device and genuinely useful: it sends real-time CO alerts to Apple Home, Google Home, Alexa, SmartThings and Home Assistant without a vendor hub or cloud account. Detection uses a FIGARO TGS5141 electrochemical sensor measuring 0 to 600 ppm, certified to UL 2034 5th Edition, with a local siren of at least 85 dB and a flashing light. The battery is a CR123A rated for ten years. It detects carbon monoxide only, so it does not replace a smoke alarm, and it needs a Thread border router.
- Homes with gas appliances or attached garages
- Matter and Thread setups
- Multi-platform households
- Alerts while away from home
Pros
- Native Matter over Thread: works with Apple Home, Google Home, Alexa, SmartThings and Home Assistant
- Named FIGARO TGS5141 electrochemical sensor, 0 to 600 ppm
- UL 2034 5th Edition certified
- Ten year battery life on a CR123A cell
- At least 85 dB siren plus a flashing light
- Real-time phone alerts and automation triggers
- No vendor hub, cloud account or subscription needed
Cons
- Detects carbon monoxide only: no smoke detection
- Requires a Thread border router, with no other radio option
- No self-test function
- No display or pathlight
- Warranty terms and dimensions are not documented
Who is the Heiman C1-M for?
Carbon monoxide is colourless and odourless, so a detector is the only warning you get, and the usual weakness of a standalone CO alarm is that it makes noise in an empty house. This one solves that by being a native Matter device: with a Thread border router present, the alarm reaches your phone through whichever platform you use, and it can trigger automations, for example turning off a boiler or opening a smart vent. Because Matter support is native rather than bridged, it works with Apple Home, Google Home, Alexa, SmartThings and Home Assistant equally.
What it offers
The sensing element is a named part, the FIGARO TGS5141 electrochemical sensor, with a measuring range of 0 to 600 ppm and UL 2034 5th Edition certification, which is the standard that matters for CO alarms. Alerts come in two forms: a local audible alarm of at least 85 dB with a flashing light, and a real-time notification through the Matter hub. Low battery warnings are included, the CR123A cell is rated for ten years, and at 136 g it is a small unit.
What to know before you buy
It detects carbon monoxide only. There is no smoke sensor, so it complements rather than replaces a smoke alarm, and homes need both. A Thread border router is required, since Thread is the only radio, with no Wi-Fi, Zigbee or Z-Wave fallback. There is no self-test function, no pathlight and no display. Warranty terms and dimensions are not documented. As with every CO alarm, the sensor has a finite service life, so plan on replacement at end of life regardless of battery state.
Is the Heiman C1-M worth it?
It costs more than a basic CO alarm and less than most connected ones, and what you get for the difference is platform-independent alerting: no vendor app, no subscription, no bridge. For a home already running Thread and Matter, that makes it one of the easiest safety devices to add. If you have no Thread border router, or you want a single unit covering both smoke and CO, a combination alarm is the better purchase.
Frequently asked questions
Does the Heiman C1-M detect smoke too?
No. It is a carbon monoxide alarm only, so it should be installed alongside smoke alarms rather than instead of them.
Does it need a hub?
It needs a Thread border router, which many smart speakers and displays now include. It does not need a Heiman hub, because Matter support is native.
Which platforms will it alert?
Apple Home, Google Home, Alexa, SmartThings and Home Assistant, all through Matter over Thread, with real-time notifications to your phone.
How long does the battery last?
Ten years, using a CR123A cell, with low battery warnings before it expires.
How loud is the alarm?
At least 85 dB, accompanied by a flashing light, in addition to the notification sent through your smart home platform.










