Heiman Smart CO Alarm Review: A Carbon Monoxide Detector That Speaks Matter over Thread
The Heiman C1-M is a carbon monoxide alarm that joins a smart home as a native Matter over Thread device, so its alerts reach Apple Home, Google Home, Alexa, SmartThings and Home Assistant through any Thread border router, with local control and no brand bridge. Detection uses a FIGARO TGS5141 electrochemical sensor measuring 0 to 600 ppm, backed by a siren of at least 85 dB and a flashing light, and the CR123A battery is rated for ten years. It detects carbon monoxide only, so it sits alongside a smoke alarm rather than replacing one, and Thread is its only radio.
- 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
- FIGARO TGS5141 electrochemical sensor, 0 to 600 ppm
- Ten year battery life on a CR123A cell
- Siren of at least 85 dB plus a flashing light
- Real-time phone alerts and automation triggers
- Local control, with no brand bridge needed
Cons
- Detects carbon monoxide only, with 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 Smart CO Alarm for?
Carbon monoxide is colourless and odourless, so a detector is the only warning you get, and a standalone alarm can only make noise in the room it is in. This one is for a home that already runs Thread and Matter: once paired, a CO event reaches your phone through whichever platform you use and can trigger automations, such as switching off a heating appliance or turning on ventilation. Because the Matter support is native, Apple Home, Google Home, Alexa, SmartThings and Home Assistant all see it the same way.
What the Heiman Smart CO Alarm offers
The sensing element is a named part, the FIGARO TGS5141 electrochemical sensor, with a measuring range of 0 to 600 ppm. Alerts come in two forms: a local audible alarm of at least 85 dB with a flashing light, and a real-time notification sent through your Matter controller. Low battery warnings are included, the CR123A cell is rated for ten years, and the unit weighs 136 g. Local control means the alarm and its automations keep working inside your network when the internet is down.
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. A Thread border router is required: Thread is the only radio, with no Wi-Fi, Bluetooth, Zigbee or Z-Wave fallback. There is no self-test function, no pathlight and no display, and it is battery powered only, with no wired option. Warranty terms and dimensions are not documented.
Is the Heiman Smart CO Alarm worth it?
What sets it apart is platform-independent alerting from a dedicated CO sensor with a named electrochemical cell and a ten year battery: no vendor app or bridge stands between the alarm and your phone. For a home already running Thread and Matter, that makes it one of the simpler safety devices to add. Without a Thread border router, or if you want one unit covering both smoke and carbon monoxide, a combination alarm is the better fit.
Frequently asked questions
Does the Heiman Smart CO Alarm 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 and a Matter controller. It does not need a Heiman hub, because its 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?
Up to ten years on a CR123A cell, with low battery warnings.
How loud is the alarm?
At least 85 dB, with a flashing light, in addition to the notification sent through your smart home platform.













