Winner
Updated October 2026
Data from the official Google and Heiman sites.
2026 verdict
For an all-in-one hardwired alarm versus a compact CO specialist, the Google Nest Protect (Wired) takes this comparison with a richer sensor suite, smoke, CO, occupancy, temperature, humidity, ambient light and motion, versus the Heiman Smart CO Alarm's CO-only sensor, a higher owner rating, self-testing, an automatic pathlight, and steam-check false-alarm filtering. The Heiman Smart CO Alarm isn't without an edge of its own: a lower price and a wider integrations list through Matter over Thread, covering Google Home, Alexa, Apple HomeKit, Samsung SmartThings and Home Assistant, three more platforms than the wired Nest Protect's Google Home and Home Assistant support. Installation differs too: the Nest Protect (Wired) runs on household power with an AA battery backup, so it needs existing alarm wiring, while the Heiman runs entirely on a replaceable battery and can go almost anywhere. Homes with hardwired alarm circuits that want deep sensing and a full smoke-and-CO alarm should choose the Google Nest Protect (Wired), while anyone needing an affordable, wire-free CO monitor with wide platform reach should pick the Heiman Smart CO Alarm.
Works with
Connectivity
- Wi-Fi 2.4 GHz
- Bluetooth
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| Feature | Google Nest Protect (Wired) | Heiman Smart CO Alarm | Winner |
|---|---|---|---|
| Price | $549.99 | $47.99 | Heiman Smart CO Alarm |
| Rating | 4.6 | 3.6 | Google Nest Protect (Wired) |
| Connectivity | 2.4 GHz WiFi, Bluetooth, Other | Thread Protocol | Google Nest Protect (Wired) |
| Integrations | Google Home, Home Assistant | Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter | Heiman Smart CO Alarm |
| Sensors | Smoke, CO, Occupancy, Temperature, Humidity, Ambient Light, Motion | CO | Google Nest Protect (Wired) |
| Alerts | Fire Alerts, CO Alerts, Low Battery Alerts | CO Alerts, Low Battery Alerts | Google Nest Protect (Wired) |
| Tests Itself | YES | NO | Google Nest Protect (Wired) |
| Pathlight | YES | NO | Google Nest Protect (Wired) |
| Steam Check | YES | NO | Google Nest Protect (Wired) |
| Screen | NO | NO | Tie |
| Built-in Siren | YES | YES | Tie |
| Built-in Light | YES | YES | Tie |
Winner
$549.99
- + Rating: 4.6
- + Connectivity: 2.4 GHz WiFi, Bluetooth, Other
- + Sensors: Smoke, CO, Occupancy, Temperature, Humidity, Ambient Light, Motion
- - Price: $549.99 vs $47.99
- - Integrations: Google Home, Home Assistant vs Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
20% OFF
Prime exclusive deal$47.99
$59.99
- + Price: $47.99
- + Integrations: Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
- - Rating: 3.6 vs 4.6
- - Connectivity: Thread Protocol vs 2.4 GHz WiFi, Bluetooth, Other
Frequently Asked Questions
Which is better overall: the Google Nest Protect (Wired) or the Heiman Smart CO Alarm?
The Google Nest Protect (Wired) wins overall on sensor breadth, owner rating, self-testing and pathlight. The Heiman Smart CO Alarm still wins on price and integrations reach.
What is the biggest difference between these two alarms?
Sensor scope and installation type. The Google Nest Protect (Wired) covers smoke, CO, occupancy, temperature, humidity, ambient light and motion, and runs on household power with a battery backup, while the Heiman Smart CO Alarm only detects carbon monoxide and runs entirely on a replaceable battery.
Does the Heiman Smart CO Alarm need wiring like the Nest Protect (Wired)?
No. The Heiman Smart CO Alarm is fully battery-powered and needs no electrical wiring, only a Thread Border Router to enable its smart home integrations. The Google Nest Protect (Wired) requires existing alarm wiring.
Which alarm supports more smart home platforms?
The Heiman Smart CO Alarm, via Matter over Thread, reaches Google Home, Alexa, Apple HomeKit, Samsung SmartThings and Home Assistant, three more platforms than the Google Nest Protect (Wired), which works with Google Home and Home Assistant.
Who should buy the Google Nest Protect (Wired)?
Homes with existing hardwired alarm circuits that want one alarm covering smoke, carbon monoxide, and a full extra sensor suite, along with self-testing and an automatic pathlight.
Who should buy the Heiman Smart CO Alarm?
Buyers without alarm wiring who just need an affordable, battery-powered carbon monoxide monitor that reaches Google Home, Alexa, Apple HomeKit or SmartThings.
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Compare all 27 Smoke & CO Detectors side by side
You are looking at two of them. The full table lines up all Smoke & CO Detectors in the catalog with the same specs, so you can filter by what you need and sort by price or rating.
- 27 Smoke & CO Detectors
- 44 specs compared
- 41 filters
- Smoke & CO Detectors
Photoelectric Smoke Alarm
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WiFi Smoke & CO Detector
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Nest Protect (Wired)
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Wi-Fi CO Alarm
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SC07-MR Smart Smoke & CO Alarm
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HS1SA-E Zigbee Smoke Alarm
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Nest Protect (Battery)
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Smart Smoke Detector
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Smoke Alarm
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XC0M-iR Smart Carbon Monoxide Alarm with Voice Alerts
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Smoke and CO Alarm HM-636THS
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Interconnected Smoke Alarm S1-R
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SD19-MN Interconnected Smart Smoke Alarm
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Matter Smoke Detector S1-TM
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Wi-Fi Smoke Alarm
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Smart Smoke & CO Detector with Ring
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Smoke Alarm E10
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Smoke Alarm HM-636PHS
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Interconnected CO Alarm C1-R
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SC5 Battery Smart Smoke & CO Alarm
- Cameras
Nest Cam (outdoor or indoor, battery)
- Cameras
Nest Cam Floodlight
- Cameras
Nest Cam Indoor (Wired, 3rd Gen)
- Cameras
Nest Cam Outdoor (Wired, 2nd Gen)
- Cameras
Nest Cam (indoor, wired)
- Displays
Nest Hub (2nd Gen)
- Displays
Nest Hub Max
- Doorbells
Nest Doorbell (battery)
- Doorbells
Nest Doorbell (wired, 3rd Gen)
- Doorbells
Nest Doorbell (wired, 2nd Gen)
- Door Locks
Nest x Yale Lock
- Routers
Nest WiFi Pro
- Smoke & CO Detectors
Nest Protect (Battery)
- Smoke & CO Detectors
Nest Protect (Wired)
- Speakers
Nest Audio
- Speakers
Nest Mini (2nd gen)
- Streaming Devices
TV Streamer (4K)
- Temperature & Humidity Sensors
Nest Temperature Sensor (2nd gen)
- Temperature & Humidity Sensors
Nest Temperature Sensor
- Thermostats
Nest Learning Thermostat (4th gen)
- Door & Window Sensors
Window Door Alarm
- Gas Detectors
HS1CG Series Combustible Gas Sensor
- Gas Detectors
WS2CG Series Combustible Gas Detector
- Motion Sensors
Smart Motion Sensor
- Motion Sensors
WiFi Smart Motion Sensor
- Sirens
Smart Siren HS2WD series
- Smoke & CO Detectors
HS1SA-E Zigbee Smoke Alarm
- Smoke & CO Detectors
Interconnected CO Alarm C1-R
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Interconnected Smoke Alarm S1-R
- Smoke & CO Detectors
Matter Smoke Detector S1-M
- Smoke & CO Detectors
Matter Smoke Detector S1-TM
- Smoke & CO Detectors
Smart CO Alarm
- Smoke & CO Detectors
Smoke Alarm HM-636PHS
- Smoke & CO Detectors
Smoke and CO Alarm HM-636THS
- Vibration Sensors
Smart Vibration Sensor HS1VS series
- Water Leak Sensors
Smart Water Leakage Sensor