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

$91.19 $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]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 55425022656

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4.2 ★★★★★
Based on 716 reviews
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Product Reviews
M
Verified Purchase
Mother of two
Chelsea, US
★★★★★ 5
Precious toy for big dogs too
Size: Large, Color: Skinny Green
Not only is this toy cute and fun, but material is thick and durable even for my crazy GSP who is a destruction artist. This is, the favorite toy his go to in the toy box.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 15, 2026
V
Verified Purchase
VanillaPepper
Lowell, US
★★★★★ 5
Indestructible Toys My Dobermans ❤️
Size: Large, Color: Mesh Green
Actually Respect! goDog Is a Lifesaver The variety of size and colors are phenomenal 😇 I have two Dobermans — serious, determined power chewers — and I’ve spent years trying to find toys that survive even a few days. I’ve tried the big brands (Kong, Goughnuts, Jolly Ball, you name it) — and while some toys last a little while, almost everything eventually ends up shredded, de-squeaked, or in pieces. goDog toys are the ONLY plush toys my Dobermans won’t destroy. We own multiple goDog toys now — dragons, dinosaurs, lizards — mostly in the large size (perfect for Dobermans), but even a few medium-sized ones hold up surprisingly well. Here’s what’s amazing: • They love them — actually carry them around, toss them, chew them gently, and squeak them happily. • They do not rip them apart — no matter how much tugging, chewing, or wrestling happens. • Large sizes are best for Dobermans (and other big breeds) — but even mediums survive for calmer play sessions. • No ripped seams, no stuffing everywhere, and no destroyed squeakers after months of use. What makes goDog toys different? The secret is their Chew Guard Technology — • A reinforced, high-strength inner mesh layer under the soft plush • Double-stitched seams • Durable yet flexible material that somehow resists punctures, tears, and brutal shaking The outside stays soft and fun, but the inside is built like armor. It’s NOT a super hard rubber or rough canvas — it still feels like a cuddle toy, but it’s engineered to survive serious chewing. Materials include: • Durable polyester plush • Chew Guard inner lining (high-tensile mesh fabric) • Reinforced stitching • Non-toxic squeakers • Safe for dogs to play with long-term Real Owner Advice: • Always size up if you have a heavy chewer — large sizes are a must for Dobermans or similarly strong breeds. • Medium sizes are fine if you supervise or your dog is more moderate with toys, but the large toys are built tougher overall. Final Thoughts: If you have big dogs, strong jaws, or just tired of wasting money on destroyed toys — goDog toys are a must. No other plush-style toy even comes close. My Dobermans will destroy almost anything… but they treat their goDog toys like treasured companions. No holes, no rips, just happy dogs. Follow me here on Amazon for more honest, dog-tested reviews! Like this review if it helped — I’ll be uploading even more proven tough toys and pet essentials soon!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 29, 2025
B
Verified Purchase
BB
West Palm Beach, US
★★★★★ 4
Surface Fabric is very durable
Size: Small, Color: Hot Pink
Surface Fabric is very durable, but the squeaker didn't last two months. I have urged the manufacturer to find a strong more durable squeaker for their product. My dogs really enoys it when the speaker works. One of his 3 work. I have just bought two more he likes them so much. He takes it to bed every night to catch it once or twice before sleeping. Also loves to catch it a few times during the day.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 11, 2026
T
Verified Purchase
Taraknits
Alexandria, US
★★★★★ 5
Best. Toy. Ever. For My Superchewer!
Size: Large, Color: Skinny Green, Size: Large, Color: Skinny Green
Best toy ever! My dog destroys toys. Usually within about 15 minutes, she has de-squeakered and defluffed them. By the second day, she has tug-of-war-ed them to shreds. From the time we got this adorable dragon out of the package, she LOVED it. She set to work. It’s been a week, and while she has dewinged him, he lost his squeaker after a few days, and he looks a bit rough, he’s still in one piece! And, we’ve had HOURS of tug-of-war with minimal rips! She’s obsessed 😍 I ordered two more today. We’ve finally found the perfect toy for my baby!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 18, 2026
S
Verified Purchase
SnowshoePete
Lake Worth, US
★★★★★ 5
My 90 lb. Pitbull's All-Time Fave Toy
Size: Large, Color: Coral, Size: Large, Color: Coral
I ordered a plethora of new toys for Bruce to keep him occupied while I am working remotely from home. Poor guy gets so bored while I'm stuck in front of my computer 8+ hours a day. All the other toys are animated, but this one is just a big floppy chewy squeaky toy. Bruce quickly lost interest in all the other chirping, hopping, and twirling toys and fell in love with "Diny". When I opened Diny and gave it to Bruce, he had the elated and surprised look of a 3 yr old at Christmas. And he stayed that happy for hours, and then each time he picked up Diny to play. Diny became his go-to toy over all others (and there are many!). It is well made out of durable fabric, and they did not stuff it full of kapoc (I hate kapoc in dogs toys!). And it is delightfully low-tech. Normally he tears a squeaky toy apart as soon as he can isolate the squeaky mechanism. But cleverly, the squeaky box is loose in the long belly so it moves from one end to the other as the toy is handled. That made it difficult for Bruce to locate it. The toy remained in good condition for 2 weeks of near constant attention by Bruce. But yesterday he zeroed in on the squeaky box and ripped Diny to shreds. I was sad to see Diny go so soon. But boy-howdy was Bruce happy with it. I'm gonna buy another because we liked it so much. And so did I : )
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 23, 2024

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