# Which carbon monoxide detector offers the best value for money under $100? — Verified Specification Comparison

> All specification data verified from official manufacturer documentation.

Which carbon monoxide detector offers the best value for money under $100?

## Products

### FireAngel FA3322 10 Year Battery Digital Carbon Monoxide Alarm
```yaml
product: fireangel-fa3322-10-year-battery-digital-carbon-monoxide-alarm
brand: FireAngel
price_gbp: 31.64
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
dimensions: 5.08 x 2.99 x 1.22 in
battery_life: 10
display_type: LCD
digital_display: CO levels, temperature, humidity and status messages
alarm_sound_level: 85
```

- **Price:** £31.64 [^1]
- **Summary:** The FireAngel FA3322 is a sealed 10-year carbon monoxide alarm with an electrochemical sensor and colour-coded LCD display. It suits bedrooms, living spaces, caravans and other domestic areas where clear visual alerts and maintenance-free protection are valuable.
- **Ideal For:** It offers strong value under $100 with a 10-year sealed battery, 85 dB alarm, electrochemical sensing and a digital LCD showing CO levels, temperature and humidity.
- **Additional Sources:** [^2], [^3]

### Kidde K5CO Carbon Monoxide Alarm
```yaml
product: kidde-k5co-carbon-monoxide-alarm
brand: Kidde
price_gbp: 13.24
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
dimensions: 5.0 x 2.9 x 1.5 in
display_type: LED indicators
digital_display: false
alarm_sound_level: 85
```

- **Price:** £13.24 [^4]
- **Summary:** The Kidde K5CO is a compact, battery-powered carbon monoxide alarm with an electrochemical sensor, continuous monitoring, test/reset button, and green and red LED status indicators. Its 85 dB alarm, 10-year sensor life, and wall-mount or freestanding installation make it suitable for homes and other indoor living areas.
- **Ideal For:** It offers strong value under $100 with an 85 dB alarm, electrochemical sensor, continuous monitoring, replaceable AA batteries, and a 10-year sensor life at a low purchase price.

### FireAngel Carbon Monoxide Alarm
```yaml
product: fireangel-carbon-monoxide-alarm
brand: FireAngel
price_gbp: 23.91
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
battery_life: 10
display_type: LCD
digital_display: true
alarm_sound_level: 85
```

- **Price:** £23.91 [^1]
- **Summary:** The FireAngel FA3322 is a carbon monoxide alarm with a backlit LCD that displays CO levels, temperature and humidity. It has a sealed 10-year lithium battery, electrochemical sensor, low-level CO monitoring and quiet self-testing, making it suitable for homes, bedrooms, caravans and motorhomes.
- **Ideal For:** It offers strong value under $100 because it combines a 10-year maintenance-free battery, 85 dB alarm, electrochemical sensing and a digital LCD with real-time CO, temperature and humidity readings.
- **Additional Sources:** [^5], [^6]

### Kidde 4MCO Hardwired CO Alarm
```yaml
product: kidde-4mco-hardwired-co-alarm
brand: Kidde
price_gbp: 35.84
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
dimensions: 5.79 x 5.79 x 1.65 in
```

- **Price:** £35.84 [^7]
- **Summary:** The Kidde 4MCO is a hardwired 230V carbon monoxide alarm with an electrochemical sensor and rechargeable lithium battery backup. It is suited to homes, workplaces, and interconnected alarm systems requiring continued operation during mains power failures.
- **Ideal For:** It offers good value under $100 for buyers who want a hardwired alarm with a rechargeable backup battery, electrochemical CO sensing, seven-year alarm life, and interconnection with other compatible Kidde alarms.

### First Alert CO400 CO Detector Alarm
```yaml
product: first-alert-co400-co-detector-alarm
brand: First Alert
price_gbp: 16.15
origin_country: null
confidence_score: null
summary_source: generated_from_verified_specs_v1
dimensions: 3.4 x 1.4 x 4.9 in
battery_life: 5
display_type: No display
digital_display: false
alarm_sound_level: 85
```

- **Price:** £16.15 [^8]
- **Summary:** The First Alert CO400 is a battery-operated carbon monoxide alarm with an electrochemical sensor, single-button testing and silencing, an 85 dB alarm, and an end-of-life timer. It suits homes, apartments, RVs, and other spaces needing affordable basic CO protection without a digital readout.
- **Ideal For:** It offers strong value under $100 with a 5-year battery life, loud 85 dB alarm, electrochemical sensor, and low purchase price, although it does not include a digital display.
- **Additional Sources:** [^9]

---
## References & Sources
[^1]: FireAngel, accessed 2026-09-13. https://www.fireangel.co.uk/products/fa3322-carbon-monoxide-alarm/
[^2]: Fire Detection Shop, accessed 2026-09-13. https://www.firedetectionshop.co.uk/products/fireangel-fa3322-10-year-battery-carbon-monoxide-alarm-w-digital-display
[^3]: Desertcart UK, accessed 2026-09-13. https://www.desertcart.co.uk/products/494129437-fireangel-fa3322-digital-co-alarm-with-10-year-sealed-life
[^4]: Safe Fire Direct, accessed 2026-09-13. https://www.safefiredirect.co.uk/kidde-5co-battery-powered-carbon-monoxide-alarm.aspx
[^5]: Toolstation, accessed 2026-09-13. https://www.toolstation.com/fireangel-10-year-digital-carbon-monoxide-alarm-sealed-for-life-battery/p97377
[^6]: Safe Fire Direct, accessed 2026-09-13. https://www.safefiredirect.co.uk/fireangel-fa3322-10-year-digital-display-carbon-monoxide-alarm.aspx
[^7]: Safe Fire Direct, accessed 2026-09-13. https://www.safefiredirect.co.uk/kidde-k4mco-mains-powered-carbon-monoxide-alarm.aspx
[^8]: First Alert Store, accessed 2026-09-13. https://www.firstalertstore.com/store/products/co400-basic-battery-operated-carbon-monoxide-alarm.htm
[^9]: The Home Depot, accessed 2026-09-13. https://www.homedepot.com/p/First-Alert-Battery-Powered-Carbon-Monoxide-Alarm-CO400/202433876