---
product_id: 53089982
title: "Firex KF20 Optical Smoke Alarm - Mains Operated with Battery Back Up"
brand: "kidde"
price: "€ 63.72"
currency: EUR
in_stock: true
reviews_count: 11
category: "Kidde"
url: https://www.desertcart.sk/products/53089982-firex-kf20-optical-smoke-alarm-mains-operated-with-battery-back
store_origin: SK
region: Slovakia
---

# Battery backup included Interlink up to 23 alarms Tamper-resistant locking Firex KF20 Optical Smoke Alarm - Mains Operated with Battery Back Up

**Brand:** kidde
**Price:** € 63.72
**Availability:** ✅ In Stock

## Summary

> 🔥 Stay ahead of danger with Kidde’s smart, connected smoke alarm! 🔗

## Quick Answers

- **What is this?** Firex KF20 Optical Smoke Alarm - Mains Operated with Battery Back Up by kidde
- **How much does it cost?** € 63.72 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.sk](https://www.desertcart.sk/products/53089982-firex-kf20-optical-smoke-alarm-mains-operated-with-battery-back)

## Best For

- kidde enthusiasts

## Why This Product

- Trusted kidde brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Smart Silence Control:** Combined test/hush button for quick nuisance alarm management
- • **Built to Last & Secure:** Tamper-resistant locking device keeps safety uncompromised
- • **Certified Peace of Mind:** BSi Kitemark certified, compliant with latest building regs
- • **Uninterrupted Vigilance:** Mains powered with battery backup ensures 24/7 reliability
- • **Seamless Networked Safety:** Interlink up to 23 alarms for whole-home protection

## Overview

The Kidde Firex KF20 is a mains-operated optical smoke alarm with a reliable 9V battery backup, designed to detect slow smouldering fires while minimizing false alarms. It supports interlinking up to 23 units for comprehensive home coverage, features a tamper-resistant lock, and includes a combined test/hush button for user-friendly operation. Certified to BSi Kitemark standards and compliant with current building regulations, it offers professional-grade safety with easy installation and maintenance.

## Description

Product Description Kidde Firex smoke alarms offer the very best in quality and reliability. Certified to the highest BSi Kitemark standards and offering a wide range of alarms to suit most applications you can be assured that you are in safe hands. The KF20 is compliant with the latest in building regulations for new housing. The KF20 utilises photo-electric (optical) detection facility. They are best suited where there is a danger of slow smouldering fires such as those caused by cigarettes for example on foam filled furniture or bedding. They are less prone to nuisance alarms caused by steam or cooking particles. They can be disposed of with general household waste. Box Contains 1 x KF2, Battery & Instructions

Review: They work and are easy to install. - Firs,t you need to check the regulations for your area. These directly exchange for for the older models if you have them (screw into existing baseplate) but would also not be too difficult to fit as new items - again, though, check if you can do this or whether you need a registered electrician,
Review: Good quality - Well, I'd like to say it works perfectly. But I don't want it to go off unless theirs a fire haha. But seems absolutely fine. 😊 thanks

## Features

- Interlink with up to 23 Firex hard-wired alarms
- Combined test/hush button
- Auto reset
- Tamper-resistant locking device
- Mains operation
- The Kidde KF2 smoke alarm is a mains powered alarm contains battery in it as a backup in case of a power cut.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B006J56XQU |
| Batteries | 1 9V batteries required. (included) |
| Batteries Required? | Yes |
| Batteries included? | Yes |
| Battery Cell Type | Alkaline |
| Best Sellers Rank | 3,829 in DIY & Tools ( See Top 100 in DIY & Tools ) 26 in Smoke Alarms |
| Colour | White |
| Customer Reviews | 4.6 4.6 out of 5 stars (1,488) |
| Date First Available | 7 Dec. 2011 |
| Delivery information | We cannot deliver certain products outside mainland UK ( Details ). We will only be able to confirm if this product can be delivered to your chosen address when you enter your delivery address at checkout. |
| Item Package Quantity | 1 |
| Item Weight | 280 g |
| Item model number | KF2 |
| Manufacturer | Kidde |
| Part Number | KF2 |
| Power Source | Battery Powered |
| Product Dimensions | 13.3 x 13.3 x 3.9 cm; 280 g |
| Style | Back Up |

## Product Details

- **Alarm:** Visual
- **Brand:** Kidde
- **Colour:** White
- **Global Trade Identification Number:** 00020967049737
- **Item weight:** 280 Grams
- **Manufacturer:** Kidde
- **Power source:** Battery Powered
- **Sensor type:** Photoelectric
- **Style:** Back Up
- **UPC:** 020967049737

## Images

![Firex KF20 Optical Smoke Alarm - Mains Operated with Battery Back Up - Image 1](https://m.media-amazon.com/images/I/515CCoZk4qL.jpg)

## Questions & Answers

**Q: Title says mains alarm. Does this actually work off the 240v mains domestic supply. There is nothing in the description that mentions transformer, ect**
A: The product voltage is 230, it works perfectly well off 240 volt with no need for a transformer as you mention.

**Q: Hi. The title of the listing says the smoke alarm is the optical kind. The listing's description says it is the ionisation kind. What is the product?**
A: The KF2 (which for your information is now the KF20 which is supplied) is an optical smoke alarm.I will amend the listing description.

**Q: Does this alarm come with a plug?**
A: It comes with a connection plug to connect the direct mains supply to the alarm.

**Q: Does it fit the plates of Deta 1111 model?**
A: No, you will need to change the mounting/base plate which is supplied with the alarm.

## Customer Reviews

### ⭐⭐⭐⭐⭐ They work and are easy to install.
*by U***K on 28 January 2026*

Firs,t you need to check the regulations for your area. These directly exchange for for the older models if you have them (screw into existing baseplate) but would also not be too difficult to fit as new items - again, though, check if you can do this or whether you need a registered electrician,

### ⭐⭐⭐⭐⭐ Good quality
*by I***N on 18 November 2025*

Well, I'd like to say it works perfectly. But I don't want it to go off unless theirs a fire haha. But seems absolutely fine. 😊 thanks

### ⭐⭐⭐⭐ low power batteries
*by A***X on 23 December 2022*

The cons first- out of the four ordered two had low battery power and I suspect the other two to be the same so I will swap out those batteries for new ... Pros - easy to install on to old firex ones so easy I let my 17 year old daughter do them all with no issues (apart from batteries) Hopefully that's them now for the next ten years

## Frequently Bought Together

- Kidde Firex KF20 Optical Smoke Alarm - Mains Operated with Battery Back Up
- Twin Pack Kidde Firex KF20 Mains Powered Optical Smoke Alarm with 9V Back Up Batteries | KF2 | 4973
- Firex KF30 Kidde Firex Alarm, White

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*Product available on Desertcart Slovakia*
*Store origin: SK*
*Last updated: 2026-03-11*