The updated Kidde Firex range of smoke and heat alarms are mains powered, interlinking units that now use up to 70% less energy than previous Firex models. Hard-wired with alkaline back-up batteries, these alarms can be interlinked with other units from the series to create all round fire protection within the home; when one alarm detects smoke/heat and sounds, all units will sound. Installing the right sensor types in your property gives you the fastest possible response time with the minimum number of false alarms.
Please Note: The Kidde KF Firex models are replacements for the older Firex 4000 series, Kidde 9HI and Kidde 9HILLs and can be interlinked, however the new models cannot be used on the same base plates and use different connector blocks.
All of our product reviews are written by real customers that have purchased this product from us and are published without modification.
P R
26th April 2026
D M
23rd April 2026
It does the job
I E
4th October 2025
Safelincs gave excellent support in finding this replacement for a missing alarm
D B
26th July 2025
Easy to fit. No issues so far.
S N
4th July 2025
Good product with prompt delivery
| Product Code | KEKF20 |
|---|---|
| Brand | Kidde |
| Back-Up Battery Type | Alkaline |
| British Standard Grade | Grade D2: Mains Powered (replaceable backup) |
| Colour | White |
| Local Legislation | Scottish Legislation (2022) |
| Welsh Legislation (2022) | |
| Approvals & Markings | CE Marked |
| Compliance | BS 5839-6 |
| BS EN 14604: 2005 | |
| Connection | Wired |
| Display | LED Indicators |
| Fixing Options | Screws (included) |
| Installation Position | Ceiling |
| Material | Plastic |
| Maximum Number of Linked Devices | 24 Devices |
| Operating Temperature | 0°C To +40°C |
| Positioning | Bedrooms |
| Hallways | |
| Living Rooms | |
| Power Type | Mains Powered (230V) |
| Product Range | Kidde Firex |
| Recyclable | Yes - Valpak's WEEE Distributor Take-back Scheme |
| Relative Humidity | Up To 93% |
| Sensor Type | Optical |
| Sound Level | 85dB |
| Suitability | Home |
| Warning Type | Audible - Alarm Sounder |
| Warranty | 6 Years |
| Dimensions (Unit) |
|
| Weight | 280g |
| Datasheets |
Alarms from the Same Series
The table below shows all the units that can interlink with the Firex KF Series.
| Model Number | Type of Unit | Type of Interlink |
| KF10 | Ionisation Smoke Alarm | Hardwire interlink |
| KF10R | Ionisation Smoke Alarm with Rechargeable Lithium Cell | Hardwire interlink |
| KF20 | Optical Smoke Alarm | Hardwire interlink |
| KF20R | Optical Smoke Alarm with Rechargeable Lithium Cell | Hardwire interlink |
| KF30 | Heat Alarm | Hardwire interlink |
| KF30R | Heat Alarm with Rechargeable Lithium Cell | Hardwire interlink |
| KF1 | Ionisation Smoke Alarm | Hardwire interlink |
| KF1R | Ionisation Smoke Alarm with Rechargeable Lithium Cell | Hardwire interlink |
| KF2 | Optical Smoke Alarm | Hardwire interlink |
| KF2R | Optical Smoke Alarm with Rechargeable Lithium Cell | Hardwire interlink |
| KF3 | Heat Alarm | Hardwire interlink |
| KF3R | Heat Alarm with Rechargeable Lithium Cell | Hardwire interlink |
Carbon Monoxide Alarms
| Model Number | Type of Unit | Type of Interlink |
| 4MCO | CO Detector with Rechargeable Lithium Cell | Hardwire interlink |
| K4MCO | CO Detector with Rechargeable Lithium Cell | Hardwire interlink |
Compatible Alarms
| Model Number | Type of Unit | Type of Interlink |
| 1239HI | Ionisation Smoke Alarm with Alkaline Battery | Hardwire interlink |
| 1239HILL | Ionisation Smoke Alarm with Lithium Battery | Hardwire interlink |
| 2239HI | Optical Smoke Alarm with Alkaline Battery | Hardwire interlink |
| 2239HILL | Optical Smoke Alarm with Lithium Battery | Hardwire interlink |
| 3239HI | Heat Alarm with Alkaline Battery | Hardwire interlink |
| 3239HILL | Heat Alarm with Lithium Battery | Hardwire interlink |
| 4870 | Ionisation Smoke Alarm with Alkaline Battery | Hardwire interlink |
| 4881 | Ionisation Smoke Alarm with Lithium Battery | Hardwire interlink |
| 4973 | Optical Smoke Alarm with Alkaline Battery | Hardwire interlink |
| 4985 | Optical Smoke Alarm with Lithium Battery | Hardwire interlink |
| 4899 | Heat Alarm with Alkaline Battery | Hardwire interlink |
| 4892 | Heat Alarm with Lithium Battery | Hardwire interlink |
| I240C | Ionisation Smoke Alarm with Alkaline Battery | Hardwire interlink |
| PADC240 | Optical Smoke Alarm with Alkaline Battery | Hardwire interlink |
Direct replacement for a much older smoke alarm - plug n play. Very happy.
Applies to option(s): KF20 Optical Smoke Alarm