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Mains Powered Smoke Alarms & Heat Alarms with Alkaline Back-up Battery - Firehawk BB Series

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From: £18.83 inc VAT
£15.69 ex VAT
Product Overview

The FHN250BB optical smoke alarms and FHN450BB heat alarms from Firehawk are mains-powered alarms with hardwire interlink, allowing up to 15 compatible alarms in the house to sound a warning to occupants when one detects a possible fire. These models feature replaceable AAA alkaline back-up batteries to ensure continued fire detection during a power cut, or if mains-power is turned off for other reasons like decorating or a blown light bulb. The unique Fast-Fix mounting base design allows alarms to be easily removed for cleaning and replacing batteries without needing to cut the power or worry about wiring, and the alarms will chirp an "end of life" warning (which can be silenced overnight) when the whole unit needs replacing after 10 years.

  • 230V mains powered with alkaline battery backup
  • 3 x AAA alkaline battery backup (included)
  • 6 year manufacturer's warranty
  • Available in two versions:
    • FHN250BB optical smoke alarm – suitable for most rooms including hallways, landings, living rooms, and bedrooms
    • FHN450BB heat alarm – suitable for rooms likely to have steam, dust, or fumes like kitchens and garages
  • Also available with lithium back-up batteries that last the full 10 year life of the alarms
  • Fast-Fix design for quick installation using Push-Fit connectors
  • Up to 15 Firehawk FHN mains-powered smoke and heat alarms can interlink in one system
  • Advanced sensor technology to ensure quick detection of fires and reduced false alarms
  • End of life warning chirp can be silenced up to 10 hours
  • Combined large test and silence button for ease of maintenance
  • Suitable for installations complying to BS 5839-6 Grade D2
  • CE marked and certified to EN 14604: 2005 (smoke alarm) / Kitemarked to BS 5446-2: 2003 (heat alarm)
  • This alarm is also suitable for the updated 2022 Scottish legislation for fire alarms in homes

Please Note: these FHN series alarms are not compatible with the older FH models.


The table below shows all alarms which can interlink via cable with the Firehawk FHN250BB and FHN450BB mains powered smoke & heat alarms.

Please Note: these FHN series alarms are not compatible with the older FH models.

Mains-Powered Alarms

Model Description Battery Backup Interlink
FHN250BB Mains Powered Optical Smoke Alarm 3x AAA Alkaline (included) Hardwire
FHN450BB Mains Powered Heat Alarm 3x AAA Alkaline (included) Hardwire
FHN250RB Mains Powered Optical Smoke Alarm 10 Year Sealed Lithium Hardwire
FHN450RB Mains Powered Heat Alarm 10 Year Sealed Lithium Hardwire


Model Description Power Interlink
FHN600Remote Battery Powered Wireless Remote Control 1x CR2025 Coin Cell IR (infrared)

Technical Data
Product Code

FHN250BB Optical Smoke Alarm:  FIFHN250BB

FHN450BB Heat Alarm:  FIFHN450BB

Brand Firehawk
Back-Up Battery

3 x AAA Alkaline Replaceable Batteries

Dimensions (HxDia)

FHN250BB Smoke: 55 x 113mm

FHN450BB Heat: 69 x 113mm

Operating Temperature

0°C to 40°C

Relative Humidity

< 85%

Sound Output


Storage Temperature

5°C to 30°C


FIFHN250BB: 0.25kg

FIFHN450BB: 0.25kg

Product Datasheets
FAQs (1)
Q. Can I put my smoke alarm on the wall, or must it be mounted on the ceiling?

The best location to install your smoke alarm is in the centre of the ceiling rather than on the wall.

During a fire, smoke initially rises and then spreads horizontally. Placing the smoke alarm in the centre of your ceiling means that it is closest to all four points of your room. This ensures that you receive the earliest possible warning of a fire.

For more information, read our guide to positioning your smoke alarm and guide to which smoke alarms are best for each room.

Key Product Features

Fast-Fix mounting base design for quick, easy installation

3x AAA alkaline battery backup and fixing pack with each alarm

Alarms can be removed quickly to easily replace the batteries

Combined large test and silence button for ease of maintenance

Pricing & Availability

Model Stock Price
FHN250BB Optical Smoke Alarm
Product Code: FIFHN250BB
Stock Level:
More than 20 in stock Expected dispatch: 28th May

£18.83 inc VAT

£15.69 ex VAT

FHN450BB Heat Alarm
Product Code: FIFHN450BB
Stock Level:
14 in stock Expected dispatch: 28th May

£19.31 inc VAT

£16.09 ex VAT

Delivery Options

The following delivery options are available on this product.

Standard Delivery

£3.19 inc VAT - Orders will be delivered in 2-3 working days with Evri

Next Working Day Delivery

£6.19 inc VAT - Orders will be delivered the next working day with Evri

For dispatch today order within

Customer Reviews

1 customer has given this product an overall rating of 5 out of 5

Reviews by real customers

All of our product reviews are written by real customers that have purchased this product from us and are published without modification.

Rating: 5 / 5 Stars

Reviewed by: S D

As promised. Very easy to install as a replacement. Very good value for money and comes with an excellent provenance.

Published on: 30th March 2023

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