SKU: 22089085520

Kidde Sentry 2x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit Base

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Description

Kidde Sentry 2x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit Mains Powered with 9V Alkaline Battery Back-Up c/w Quick Fit BaseKidde Sentry 2x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit with 9V Battery Back Up The Kidde Sentry Alarm Kit combines two KF21 Optical Smoke Alarms and one KF31 Heat Alarm to deliver comprehensive fire detection for residential properties. Designed for mains powered installation, all alarms feature 9V alkaline battery back up and can be interconnected with up to 23 compatible Kidde FIREX alarms for reliable whole home protection. This alarm bundle

Kidde Sentry 2x KF21 Optical Smoke & 1x KF31 Heat Alarm Kit with 9V Battery Back-Up

The Kidde Sentry Alarm Kit combines two KF21 Optical Smoke Alarms and one KF31 Heat Alarm to deliver comprehensive fire detection for residential properties. Designed for mains-powered installation, all alarms feature 9V alkaline battery back-up and can be interconnected with up to 23 compatible Kidde FIREX alarms for reliable whole-home protection.

This alarm bundle is ideal for meeting UK Building Regulations in domestic properties, providing dependable smoke detection in living areas and hallways, alongside heat detection in kitchens, garages and loft spaces.

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 allows for a tidy retrofit when replacing existing alarms.

Kit Contents

  • 2 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, furniture or cigarettes. Ideal for circulation 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 triggered 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 specifically designed for kitchens, garages and loft spaces where smoke alarms may be unsuitable due to steam, fumes or dust. The thermistor heat sensor delivers dependable heat detection while helping to minimise nuisance alarms.

  • Mains-powered heat alarm with 9V alkaline battery back-up
  • Thermistor heat sensor for reliable temperature detection
  • Interconnects with up to 23 Kidde FIREX alarms
  • Alarm memory identifies the triggered 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

  • Complete smoke and heat alarm 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 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 carried out 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: 22089085520

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★★★★★ 5
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The dogs love the chuck it brand. I don’t know what it’s made of but they go crazy over them. Will not play with another ball. Wonder if it’s “laced” with an addictive scent. Have pits. Very durable. Not able to chew to pieces. Last for about 6 months before there is a small break. I keep a back up because when the ball goes missing the house is in chaos. 😆 🤪
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Reviewed in the United States on March 27, 2026
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Tatiana
Houston, US
★★★★★ 5
Most durable ball!
Size: Medium
This are my dogs fav ball 😍 they last forever!
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Reviewed in the United States on April 23, 2026
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Nana
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★★★★★ 4
Chuckit medium rebound balls
Size: Medium
My 8 month old German shepherd dog loves these balls. They are easy to throw, they bounce great, they are very chewable! She keeps one in her mouth most of the time. It satisfies her need to chew and she does not chew other things. She drops it in the water and lets the hole fill up and drinks that way. The only problem that has caused is suction in her mouth and difficulty in dislodging it for her. However, she would be lost without it!
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Reviewed in the United States on April 19, 2023
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Helena
Alexandria, US
★★★★★ 5
These are definitely indestructible
Size: Medium
Both of my dogs can destroy a ball in a matter of minutes if I let them play with them (supervised) as is. Well not with these balls. They are the ONLY ones I have found that are 100% indestructible. Please only let your dogs play with these as a toy when supervised though. They go really far when throwing them, so both dogs get a good amount of running and exercise with these. I also bought these because they have the hole in the middle of the ball which is very important in the event that a dog gets one stuck at the back of their throat. This allows them to breath unlike those without this hold. It's an unlikely event, but as dog owners, we all need to be aware of this and educate ourselves on what to do if this SHOULD happen. This isn't a scare tactic, nor a reflection of this particular brand, it can happen with any type of ball. My two dogs are about 45ish lbs and the size is perfect for them, I don't want anything smaller than this. They love them. There is no annoying squeak. Really easy to wash after use. Some balls take forever to get the slimy saliva off, but these don't.
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Reviewed in the United States on September 25, 2025
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Ale quintero
Houston, US
★★★★★ 5
He loves this ball
Size: Medium, Size: Medium
My dog loves this ball. It’s the perfect size, he enjoys playing fetch and this ball has been his fav one. Thank you guys for making my lil one happy
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