The Kidde KF21 Sentry Optical Smoke Alarm is a reliable mains-powered smoke detector designed to provide early warning of slow, smouldering fires within residential properties. Featuring an advanced optical sensor, the KF21 is ideal for hallways, landings, bedrooms, living areas and loft spaces, helping to improve fire safety throughout the home.
This interconnectable smoke alarm can be linked with up to 23 compatible Kidde FIREX smoke, heat and carbon monoxide alarms, ensuring that when one alarm detects danger, all connected alarms sound simultaneously for maximum protection.
Designed with installers in mind, the KF21 includes a Quick-Fit Slide-On Base for fast and tidy installation, while the 150mm flared base plate neatly covers marks left by larger existing alarms during retrofit projects.
Key Features
Mains-powered optical smoke alarm with 9V alkaline battery back-up
Interconnects with up to 23 compatible Kidde FIREX alarms
Advanced optical sensor for detecting slow, smouldering fires
Quick-Fit Slide-On Base for rapid installation
150mm flared base plate for clean retrofitting
Integrated cable management for secure and tidy wiring
Alarm memory identifies the triggered alarm within the network
Combined Test/Hush button for testing and silencing nuisance alarms
Auto reset following alarm activation
Tamper-resistant locking mechanism
Suitable for lofts, hallways, bedrooms and living rooms
Fully compatible with Kidde FIREX smoke, heat and CO alarms
10-year manufacturer warranty
Ideal Applications
The Kidde KF21 optical smoke alarm is suitable for installation in:
Hallways and circulation routes
Bedrooms
Living rooms
Attics and loft spaces
Residential properties requiring Grade D2 fire detection
Optical smoke alarms are particularly effective at detecting slow-burning fires caused by upholstery, electrical faults or cigarettes, making them ideal for living spaces and escape routes.
Technical Specifications
Model: KF21
Power Supply: 230V mains with 9V alkaline battery back-up
Sensor Type: Optical with dust compensation and bug screen
Alarm Volume: Minimum 85dB at 3 metres
Alarm Frequency: 3.2 kHz typical
Interconnectivity: Up to 23 compatible alarms
Alarm Grade: D2
Approvals: BSI certified to BS EN14604:2005
Dimensions: 150mm x 53mm
Weight: 295g including battery
Operating Temperature: -10°C to +40°C
Humidity Range: Up to 93% RH non-condensing
Warranty: 10 Years
Compliance & Installation
The Kidde KF21 complies with UK Building Regulations and BS 5839 Part 6 requirements for Grade D domestic fire alarm systems. Installation should be carried out by a qualified electrician. For kitchen installations, a dedicated Kidde FIREX heat alarm is recommended instead of a smoke alarm.
The Kidde KF21 Sentry Optical Smoke Alarm is a reliable mains-powered smoke detector designed to provide early warning of slow, smouldering fires within residential properties. Featuring an advanced optical sensor, the KF21 is ideal for hallways, landings, bedrooms, living areas and loft spaces, helping to improve fire safety throughout the home.
This interconnectable smoke alarm can be linked with up to 23 compatible Kidde FIREX smoke, heat and carbon monoxide alarms, ensuring that when one alarm detects danger, all connected alarms sound simultaneously for maximum protection.
Designed with installers in mind, the KF21 includes a Quick-Fit Slide-On Base for fast and tidy installation, while the 150mm flared base plate neatly covers marks left by larger existing alarms during retrofit projects.
Key Features
Mains-powered optical smoke alarm with 9V alkaline battery back-up
Interconnects with up to 23 compatible Kidde FIREX alarms
Advanced optical sensor for detecting slow, smouldering fires
Quick-Fit Slide-On Base for rapid installation
150mm flared base plate for clean retrofitting
Integrated cable management for secure and tidy wiring
Alarm memory identifies the triggered alarm within the network
Combined Test/Hush button for testing and silencing nuisance alarms
Auto reset following alarm activation
Tamper-resistant locking mechanism
Suitable for lofts, hallways, bedrooms and living rooms
Fully compatible with Kidde FIREX smoke, heat and CO alarms
10-year manufacturer warranty
Ideal Applications
The Kidde KF21 optical smoke alarm is suitable for installation in:
Hallways and circulation routes
Bedrooms
Living rooms
Attics and loft spaces
Residential properties requiring Grade D2 fire detection
Optical smoke alarms are particularly effective at detecting slow-burning fires caused by upholstery, electrical faults or cigarettes, making them ideal for living spaces and escape routes.
Technical Specifications
Model: KF21
Power Supply: 230V mains with 9V alkaline battery back-up
Sensor Type: Optical with dust compensation and bug screen
Alarm Volume: Minimum 85dB at 3 metres
Alarm Frequency: 3.2 kHz typical
Interconnectivity: Up to 23 compatible alarms
Alarm Grade: D2
Approvals: BSI certified to BS EN14604:2005
Dimensions: 150mm x 53mm
Weight: 295g including battery
Operating Temperature: -10°C to +40°C
Humidity Range: Up to 93% RH non-condensing
Warranty: 10 Years
Compliance & Installation
The Kidde KF21 complies with UK Building Regulations and BS 5839 Part 6 requirements for Grade D domestic fire alarm systems. Installation should be carried out by a qualified electrician. For kitchen installations, a dedicated Kidde FIREX heat alarm is recommended instead of a smoke alarm.
