Heiman C1-S Review: A Standalone CO Alarm With a 10-Year Battery
The Heiman C1-S is a compact, battery-powered carbon monoxide alarm for people who want certified CO protection without wiring, a hub or an app. Its Japan-made FIGARO electrochemical sensor, UL 2034 5th Edition certification, 85 dB audio-visual alarm and 10-year lithium battery cover the essentials, and the magnetic mount makes placement easy. The trade-off is that it is completely standalone: no phone alerts, no smart home integrations and no smoke detection. At a budget-friendly price it is a straightforward way to add basic CO coverage to a bedroom, hallway, rental or second home.
- Renters
- Landlords
- Bedrooms and hallways
- Budget buyers
- Second homes and cabins
Pros
- Japan-made FIGARO electrochemical CO sensor, certified to UL 2034 5th Edition
- Sealed 10-year lithium battery, with no wiring or annual battery changes
- Loud 85 dB audio alarm with a flashing LED
- Low battery and end-of-life reminders
- Compact disc body with magnetic wall or ceiling mounting
- One-touch test and silence button
- 10-year limited warranty
Cons
- Standalone alarm with no wireless radio, so no phone alerts or smart home integrations
- Detects carbon monoxide only, with no smoke sensor
- No display for live CO readings
- Sealed battery means the whole unit is replaced at end of life
- Testing is a manual button press, with no automatic self-test advertised
Who is the Heiman C1-S for?
It suits anyone who needs a reliable carbon monoxide alarm without an electrician: renters, landlords furnishing a unit, or a household adding coverage to a bedroom, hallway, basement or garage. Because it runs on a sealed battery and mounts with a magnetic bracket, there is no wiring and no outlet to reach. It is also a sensible choice for a cabin, a rental property or a second home where a simple local alarm is enough and a connected system would be overkill.
What the Heiman C1-S offers
The core is a Japan-made FIGARO electrochemical sensor, certified to UL 2034 5th Edition and CSFM approved, that watches for carbon monoxide around the clock. When it detects a dangerous level, the alarm sounds at 85 dB and an LED provides a visual warning, with a one-touch test and silence button for routine checks. A sealed CR123A lithium battery is rated for up to 10 years, so the unit does not need hardwiring or annual battery swaps. The compact disc body measures about 70 mm across and 37 mm tall, weighs around 3.7 ounces, and mounts on a wall or ceiling with the included hardware or the magnetic bracket. Low battery and end-of-life reminders tell you when the alarm needs attention.
What to know before you buy
This is a local alarm, not a smart one. It has no Wi-Fi, Bluetooth, Zigbee, Z-Wave or Thread radio, so it sends no notifications and cannot be linked to Google Home, Alexa, Apple Home, SmartThings or Home Assistant. It detects carbon monoxide only, with no smoke sensor, and it has no display for live CO readings. The battery is sealed, so the whole unit is replaced at the end of its service life rather than opened for a new cell. Testing is done with the button; the alarm does not advertise an automatic self-test routine. If you want app alerts, linked alarms or combined smoke and CO detection, choose a connected or combination model instead.
Is the Heiman C1-S worth it?
For basic, certified CO protection at a budget-friendly price, yes. It covers the essentials well: a quality electrochemical sensor, a current safety standard, a loud audio-visual alarm, a long battery rating and an easy mount. What you give up is connectivity and smoke detection, so it works best as part of a simple local safety setup rather than a smart home system. Households that want remote alerts or one device for both smoke and CO should spend more on a connected combination alarm.
Frequently asked questions
Does the Heiman C1-S need Wi-Fi or a hub?
No. It is a standalone alarm with no wireless radio, so it works as soon as it is mounted and needs no router, hub or app.
Does the Heiman C1-S detect smoke as well as carbon monoxide?
No. It is a carbon monoxide alarm only, so smoke protection needs a separate smoke alarm or a combination unit.
What battery does the Heiman C1-S use?
A sealed CR123A lithium battery rated for up to 10 years. The alarm gives low battery and end-of-life reminders, and the whole unit is replaced when the battery reaches the end of its service life.
Does the Heiman C1-S work with Alexa, Google Home or Home Assistant?
No. It has no radio and is not a Matter device, so it cannot connect to Alexa, Google Home, Apple Home, SmartThings or Home Assistant.
What safety standard does the Heiman C1-S meet?
It is certified to UL 2034 5th Edition and CSFM approved, and it uses a Japan-made FIGARO electrochemical sensor.
Can the Heiman C1-S be mounted on a wall or ceiling?
Yes. It can be wall or ceiling mounted with the included hardware or the magnetic mounting bracket, and it can also be placed on a flat surface.













