Kidde Sentry 3x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit Base
SKU: 55425022656

Kidde Sentry 3x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit Base

Sale price$91.19 Regular price$101.32
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Description

Kidde Sentry 3x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit BaseKidde Sentry 3x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit with 9V Battery Back Up The Kidde Sentry Alarm Kit combines three KF21 Optical Smoke Alarms and one KF31 Heat Alarm to provide comprehensive fire detection coverage throughout residential properties. Designed for mains powered installation, each alarm features a 9V alkaline battery back up and can be interconnected with up to 23 compatible Kidde FIREX alarms for complete whole home

Kidde Sentry 3x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit with 9V Battery Back-Up

The Kidde Sentry Alarm Kit combines three KF21 Optical Smoke Alarms and one KF31 Heat Alarm to provide comprehensive fire detection coverage throughout residential properties. Designed for mains-powered installation, each alarm features a 9V alkaline battery back-up and can be interconnected with up to 23 compatible Kidde FIREX alarms for complete whole-home protection.

This alarm bundle is ideal for larger homes and multi-room residential properties, offering dependable smoke detection in hallways, landings, bedrooms and living areas, alongside dedicated heat detection for kitchens, garages and loft spaces.

Each alarm is supplied with Kidde’s Quick-Fit Slide-On Base for fast and tidy installation. Integrated cable management helps maintain organised wiring, while the 150mm flared base ensures a clean finish during retrofit installations.

Kit Contents

  • 3 x Kidde KF21 Optical Smoke Alarms
  • 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 electrical faults, upholstery or cigarettes. Ideal for escape routes and living spaces, the KF21 provides reliable 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 activated alarm
  • 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 designed for kitchens, garages and loft spaces where smoke alarms may be unsuitable due to steam, cooking fumes or dust. The thermistor heat sensor provides dependable heat detection while helping reduce 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 activated alarm
  • Combined Test/Hush button
  • Auto reset after activation
  • Tamper-resistant locking mechanism
  • Ideal for kitchens, garages and loft spaces
  • BSI certified to BS 5446 Part 2:2003
  • 10-year warranty

Key Benefits

  • Comprehensive smoke and heat alarm solution for larger homes
  • Interlinked alarms provide whole-home warning when danger is detected
  • Quick-Fit bases for fast and simple installation
  • Integrated cable management for neat wiring
  • Suitable for compliance with UK Building Regulations
  • Grade D domestic 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]
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SKU: 55425022656

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Melissa Thompson
Draper, US
★★★★★ 4
Cute
Size: 9 Toddler, Color: Tan
Cute and great option for preschool that requires more tennis style shoes. Love the strap is longer and can be trimmed down. Seems to have nice support and daughter can easily put them on and off herself. Only downside is the the tan area scuffs pretty easily. We purchased a different pair last year (same brand and looks very similar) and they held up from scuffing better.
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Reviewed in the United States on October 29, 2023
L
Verified Purchase
Liv Martin
Draper, US
★★★★★ 5
Beautiful shoes
Size: 7 Toddler, Color: Tan, Size: 7 Toddler, Color: Tan
Beautiful dressy shoes! I used to get another version of these for size 6 when my daughter was younger, now she’s getting into size 7, I got her a pair of these. They look great on her and she loves them. Hope they will last a while. The size 6 we had were very worn because she loves them so much that she would pick them over all her other shoes.
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Reviewed in the United States on March 16, 2025
D
Verified Purchase
DB
Alexandria, US
★★★★★ 5
Grand daughter likes them, she is 2 1/2 .win win!!
Size: 7 Toddler, Color: Tan
My grand daughter loves these shoes. She is 2 1/2. They are comfortable on her. Her favorite was the white 360 walking shoe but they unfortunately don’t make them in toddler size. (Hint: make them in larger sizes - and why not? ). So I got her these. Stride Rite are good, comfortable shoes for little ones.
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Reviewed in the United States on August 3, 2025
B
Verified Purchase
Brianna LeVasseur
Natrona Heights, US
★★★★★ 3
Could Be Better
Size: 11 Little Kid, Color: Tan
Look cute for a little while, then the toes peel as shown by other reviewers. It’s such a shame because my four year old LOVES the sparkly stars on the toes. I wish they made a more expensive version in a material that wouldn’t look worn so quickly.
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Reviewed in the United States on November 16, 2025
A
Verified Purchase
Amazon Customer
New York, US
★★★★★ 5
Wonderful, sturdy shoe
Size: 9 Toddler, Color: Tan
I love this shoe. Unfortunately I ordered a size too small this time, but it really is a great shoe.
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Reviewed in the United States on October 9, 2025

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