SKU: 18187191542

Kidde Sentry 1x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit Base

Sale price$52.70 Regular price$58.56
Save 10%

Pay in installments of $14.64 with ShopPay, AfterPay and Klarna

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 22 - Jul 27

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

Kidde Sentry 1x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit BaseKidde Sentry KF21 & KF31 Mains Powered Smoke and Heat Alarm Kit with 9V Battery Back Up The Kidde Sentry Alarm Kit combines the reliable KF21 Optical Smoke Alarm and KF31 Heat Alarm to provide comprehensive fire detection throughout residential properties. Designed for mains powered installation, both alarms feature 9V alkaline battery back up protection and can be interconnected with up to 23 compatible Kidde FIREX alarms for complete home safety

Kidde Sentry KF21 & KF31 Mains Powered Smoke and Heat Alarm Kit with 9V Battery Back-Up

The Kidde Sentry Alarm Kit combines the reliable KF21 Optical Smoke Alarm and KF31 Heat Alarm to provide comprehensive fire detection throughout residential properties. Designed for mains-powered installation, both alarms feature 9V alkaline battery back-up protection and can be interconnected with up to 23 compatible Kidde FIREX alarms for complete home safety coverage.

This convenient alarm combination is ideal for meeting UK Building Regulations in domestic properties, offering dependable smoke and heat detection across living spaces, hallways, kitchens, garages and loft areas.

Each alarm is supplied with Kidde’s Quick-Fit Slide-On Base for faster installation, while integrated cable management keeps wiring neat and secure. The 150mm flared base also provides a tidy finish when replacing existing alarms.

Kit Contents

  • 1 x Kidde KF21 Optical Smoke Alarm
  • 1 x Kidde KF31 Heat Alarm

KF21 Optical Smoke Alarm Features

The Kidde KF21 optical smoke alarm is designed to detect slow, smouldering fires commonly caused by furniture, electrical faults and cigarettes. Ideal for escape routes and living areas, the alarm provides dependable early warning protection.

  • Mains-powered optical smoke alarm with 9V alkaline battery back-up
  • Optical sensor with dust compensation and bug screen
  • Interconnects with up to 23 Kidde FIREX alarms
  • Alarm memory identifies the triggered unit
  • Combined Test/Hush button
  • Auto reset after activation
  • Tamper-resistant locking mechanism
  • Suitable for hallways, bedrooms, lofts and living rooms
  • BSI certified to BS EN14604:2005
  • 10-year warranty

KF31 Heat Alarm Features

The Kidde KF31 heat alarm is ideal for kitchens, garages and loft spaces where smoke alarms may be affected by steam, cooking fumes or dust. The thermistor heat sensor provides reliable temperature detection without nuisance alarms.

  • Mains-powered heat alarm with 9V alkaline battery back-up
  • Thermistor heat sensor for reliable heat detection
  • Interconnects with up to 23 Kidde FIREX alarms
  • Alarm memory identifies the triggered unit
  • Combined Test/Hush button
  • Auto reset after activation
  • Tamper-resistant locking mechanism
  • Ideal for kitchens, garages and humid environments
  • BSI certified to BS 5446 Part 2:2003
  • 10-year warranty

Key Benefits

  • Complete smoke and heat detection solution for residential properties
  • Interlinked alarms provide whole-home warning when danger is detected
  • Quick-Fit bases for fast and clean installation
  • Integrated cable management for tidy wiring
  • Suitable for compliance with UK Building Regulations
  • Grade D fire alarm system solution
  • Fully compatible with Kidde FIREX smoke, heat and CO alarms

Technical Specifications

KF21 Optical Smoke Alarm

  • Model: KF21
  • Power Supply: 230V mains with 9V alkaline battery back-up
  • Sensor Type: Optical
  • Alarm Volume: 85dB minimum at 3 metres
  • Dimensions: 150mm x 53mm
  • Weight: 295g
  • Operating Temperature: -10°C to +40°C
  • Warranty: 10 Years

KF31 Heat Alarm

  • Model: KF31
  • Power Supply: 230V mains with 9V alkaline battery back-up
  • Sensor Type: Thermistor heat sensor
  • Alarm Volume: 85dB minimum at 3 metres
  • Dimensions: 150mm x 150mm x 66mm
  • Weight: 281g
  • Operating Temperature: -10°C to +40°C
  • Warranty: 10 Years

Please Note: Alarms are supplied individually within the kit. Installation should be completed by a qualified electrician.

Downloads

KF21 Data Sheet:
Download KF21 Data Sheet

KF31 Data Sheet:
Download KF31 Data Sheet

KF21 Instruction Manual:
Download KF21 Instruction Manual

KF31 Instruction Manual:
Download KF31 Instruction Manual

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 18187191542

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.8 ★★★★★
Based on 27 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
N
Verified Purchase
NCarr
West Palm Beach, US
★★★★★ 5
Excellent frother!!
Color: Black
If super silky froth is your game, this Maestri House frother is the name!! PERFECT froth from day 1!! Very solid and well made for a great price point (especially right now with a $15 coupon)! Even better than the higher priced model we had for years. So glad I took the risk!!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 8, 2026
A
Verified Purchase
Amazongirl
Port Orchard, US
★★★★★ 4
Almost perfect
Color: White
Stainless steel. Holds a large quantity of milk (enough for two). Works well with alternative milks. Easy to clean. Easy set up and instructions. Frothing, heating, cold foam, and hot chocolate options. Perfect temp. Not 5 stars because of the constant high pitched squeel sound it makes. Almost enough to make me return it!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 2, 2025
H
Verified Purchase
Heather Hap
Cuba, US
★★★★★ 5
Hot cocoa every morning!
Color: White
I absolutely love this machine. I make my hot cocoa every morning with it. It is so easy you just put the milk in and high-quality hot chocolate mix. Push the button and then it just whips it up and gives it a little bit of a froth on the top when it’s finished. It’s so fast and easy. It would be a great gift for anybody that likes hot chocolate.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 3, 2026
H
Verified Purchase
H. Glezos
Los Angeles, US
★★★★★ 5
Best way for hot chocolate
Color: Black
works great, I use it for hot chocolate. Easy to clean. Something to consider though the Max light may be a little lower than shown depending on the milk you use.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 17, 2026
E
Verified Purchase
Elizabeth Cook
Lexington, US
★★★★★ 2
Check your milk preference when buying this unit. Product Does not last
Color: White
I purchased this frother in mid Oct and less than 90 days later, it's no longer working. The wisk does not spin, and the element does not heat the milk. I am currently working with customer support on a refund / replacement, but so far not happy. I've been told it does not work with 2% organic milk and that I need to switch to whole milk, which will solve my issues. Not sure how whole milk will help with the heating element? This was not disclosed when I purchased the unit. If I had known my milk choice would impact the frother, I would have chosen another brand or product. I like the unit, it's compact, easy to clean, but it did not last.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 12, 2026

recommand products