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This mains-powered optical smoke alarm is designed to be interconnected with up to 23 other Kidde mains alarms, whether they are ionisation, optical, or heat alarms, allowing for a comprehensive safety network throughout the home. When one unit detects danger, all interconnected alarms will sound, providing a robust warning system. Specifically suited for hallways, bedrooms, and living areas where slow, smouldering fires may occur due to cigarettes, this alarm should be professionally installed by a qualified electrician. It is not recommended for kitchen use; instead, a Firex Heat Alarm is advised for that area. Additionally, this unit meets UK Building Regulations for new housing and adheres to the standards set out in Grade D BS 5839, Part 6.
| Model | KF20 |
| Power Supply | 230V mains-powered with 9V Alkaline battery back-up |
| Temperature Range | 0ºC to + 40ºC |
| Humidity Range | Up to 93% Relative Humidity (RH) non-condensing |
| Storage and Transport | -20ºC to +60ºC and 5–95% relative humidity (RH) non-condensing |
| Alarm Dimensions | 127 x 127 x 39mm |
| Bracket Dimensions | 133 x 133 x 6mm |
| Alarm Weight | 242g |
| Warranty | 6 years |
| Approvals | BSI certified to BS EN14604:2005 |
| Sensor | Optical, circular lateral chamber with insect-resistant width slot entry portals and added bug screen mesh |
| Chamber Size | 35mm outside diameter x 16mm depth approximate (external) |
| Detection Band | Infrared light wavelength |
| Button Test | Simulates the effect of smoke within the sensing chamber, checks electronics and sounder |
| Automatic Self-test | Circuitry is tested and unit beeps (chirps) if fault is detected |
| Supply Voltage | 230V AC, 50 Hz (nominal UK voltage) |
| Power Consumption | |
| Connection | Push-in/snap-fit type connector with 150mm long flying leads (supplied) |
| Battery Back-up | User-replaceable alkaline 9V battery (522/6LR61) |
| Power-on Indicator | Continuous green LED |
| Alarm Sounder | Electronic piezo-electric sounder (T3 pattern sound - 3 pulses - space - 3 pulses), soldered contacts |
| Sound Output | 85dB (A) minimum at 3 metres |
| Alarm Frequency | 3.2 kHz typical |
| Dust Protection | In-built foam gasket in rear of alarm to prevent dust ingress into rear of the alarm |
| Alarm Status | Red LED flashes approx once every five minutes = normal operation; Red LED flashes once a second = sensing smoke (sounder alarm sounds); Red LED flashes once every ten seconds = in hush condition (auto-reset after 15 minutes) |
| Interconnection | Up to 24 Firex and Kidde ‘Slick’ units (smoke, heat and CO) can be hardwire interconnected with optional control (see below) |
| Optional Controls | Wired Remote Test and Hush Unit (REMTH) allows test and hush of interlinked units |
| Optional Pattresses | SMK23RU also has integral switchable relay for operating remote devices; SMK4896 – Surface mounting base for added ease of installation |
| Fixing | Mounting bracket ring supplied with two ‘T’ slot fitting option; 57mm spacing to a maximum of 90mm for standard screw fittings on back boxes; Bracket has 50mm diameter central access hole for cabling |
| Plastics used | NORYL – Cover, main body and mounting bracket |
| Lead-Free Status | All Firex alarms are lead-free |
Wondering which smoke alarm you need?
Our Smoke and Gas Detectors Buying Guide has a wealth of information to help you decide which Smoke Alarms to buy, plus installation tips, maintenance advice, and guidance on certification standards and relevant regulations to be aware of.
What power supply does the KF20 Fire Alarm require and does it have a battery backup?
The KF20 Fire Alarm needs a 230V AC, 50 Hz mains power and includes a 9V alkaline battery for backup during power outages. The green LED indicates power-on status, and the battery is user-replaceable.
Can the KF20 Fire Alarm connect with other alarms, and are there optional controls?
Yes, it can interconnect with up to 24 Firex and Kidde ‘Slick’ units. Optional controls include a Wired Remote Test and Hush Unit (REMTH) for managing interconnected units and optional pattresses like the SMK23RU with a relay for external devices.
What are the size and installation requirements of the KF20 Fire Alarm?
The alarm measures 127 x 127 x 39mm, and the bracket is 133 x 133 x 6mm. It weighs 242g and includes a mounting bracket for easy installation, compatible with standard screw fittings on back boxes.
What certifications does the KF20 Fire Alarm have, and what is its warranty period? The alarm is BSI certified to BS EN14604:2005 and CE tested and certified, ensuring compliance with safety standards. It comes with a 6-year warranty, offering protection against defects and malfunctions.
