Heiman HM-636THS Review: A No-Wiring Smoke and CO Alarm With a 10-Year Sealed Battery
The Heiman HM-636THS is a standalone combination smoke and carbon monoxide alarm that runs on a sealed lithium battery rated for 10 years, so it needs no wiring, no replacement batteries and no smart home setup. It pairs a dual-beam photoelectric smoke sensor (UL 217 10th Edition) with an electrochemical CO sensor (UL 2034 5th Edition) and sounds an 85 dB alarm. The trade-off is that it is entirely local: no app alerts, no hub and no Matter, Alexa or Home Assistant connection, and it cannot be linked to other alarms. It is a budget-friendly way to cover bedrooms and hallways with both hazards in one device.
- Landlords and property managers
- Renters
- Budget buyers
- Set-and-forget installs
Pros
- Smoke and carbon monoxide detection in one unit
- Dual-beam photoelectric smoke sensor, UL 217 10th Edition
- Electrochemical CO sensor, UL 2034 5th Edition
- 10-year sealed battery, no wiring or battery changes
- 10-year limited warranty
- 85 dB alarm with flashing LED and alarm memory
- Low battery and end-of-life warnings
Cons
- No wireless radio, so no app alerts or smart home integrations
- Cannot be interconnected with other alarms
- Sealed battery means the whole unit is replaced after 10 years
- No display for live CO readings
Who is the Heiman HM-636THS for?
It suits anyone who needs both smoke and carbon monoxide coverage in rooms where running a wire is impractical: bedrooms, hallways, basements, rental units and older homes. The sealed battery is rated for 10 years and the unit is replaced as a whole when it reaches end of life, which makes it a low-maintenance choice for a landlord covering many apartments. It mounts on a twist-and-click bracket and ships with its mounting kit and manual.
What the Heiman HM-636THS offers
The smoke side uses a dual-beam photoelectric sensor, the type that responds to slow smoldering fires and is designed to tell cooking smoke and steam apart from a real fire, which cuts down on nuisance alarms. It is certified to UL 217 10th Edition. The carbon monoxide side is an electrochemical sensor that reads 0 to 2000 ppm and is certified to UL 2034 5th Edition. When something is detected it sounds an 85 dB alarm with a flashing red LED, and the alarm memory flashes the LED every 20 seconds to show that an alarm went off while you were away. Built-in diagnostics cover faults, low battery and end of life, and a test and silence button lets you check the alarm and hush a nuisance trigger.
What to know before you buy
This is not a smart alarm. It has no Wi-Fi, Bluetooth, Zigbee, Z-Wave or Thread radio, so there are no phone notifications, no remote silencing and no link to Google Home, Alexa, Apple Home, SmartThings or Home Assistant. It also has no wireless interconnect, so each unit sounds on its own rather than setting off the others. The battery is sealed and cannot be replaced, and the unit has no display for reading the CO level. If you need alerts while you are away or a whole-home linked system, look at a connected or interconnected model instead.
Is the Heiman HM-636THS worth it?
For its tier, yes if what you want is certified, maintenance-free protection rather than connectivity. Two certified sensors, a 10-year warranty and a 10-year battery in one battery-powered unit is hard to beat on running cost, and it is also sold in 3-packs and 6-packs for covering a whole building. Anyone who wants alerts on a phone should look at a connected alarm.
Frequently asked questions
Does the Heiman HM-636THS need Wi-Fi or a hub?
No. It is a standalone alarm with no wireless radio, so it works the moment it is mounted and sends no alerts to a phone or a hub.
Can the battery in the Heiman HM-636THS be replaced?
No. It uses a sealed lithium battery rated for 10 years. When the unit reaches end of life it chirps a warning and the whole alarm is replaced.
Does the Heiman HM-636THS 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 does the Heiman HM-636THS detect?
Smoke, with a dual-beam photoelectric sensor certified to UL 217 10th Edition, and carbon monoxide, with an electrochemical sensor certified to UL 2034 5th Edition.
How loud is the Heiman HM-636THS alarm?
The alarm sounds at 85 dB with a flashing red LED. A test and silence button lets you test it and hush a nuisance alarm.













