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.
Please Note: these FHN series alarms are not compatible with the older FH models.
All of our product reviews are written by real customers that have purchased this product from us and are published without modification.
M R
11th May 2026
K M
1st January 2026
The heat alarm links to the fire alarms.
Very pleased with these products.
S D
30th March 2023
As promised. Very easy to install as a replacement.
Very good value for money and comes with an excellent provenance.
| Product Code | FIFHN250BB |
|---|---|
| Brand | Firehawk |
| Back-Up Battery Type | Alkaline |
| Battery Type | AAA Batteries |
| British Standard Grade | Grade D2: Mains Powered (replaceable backup) |
| Colour | White |
| Local Legislation | Scottish Legislation (2022) |
| Welsh Legislation (2022) | |
| Approvals & Markings | CE Marked |
| UKCA Marked | |
| Compliance | BS 5839-6 |
| BS EN 14604: 2005 | |
| Connection | Wired |
| Display | LED Indicators |
| Environmental Suitability | Indoors |
| Fixing Options | Screws (included) |
| Installation Position | Ceiling |
| Material | Plastic |
| Maximum Number of Linked Devices | 12 Devices |
| Operating Temperature | 0°C To +40°C |
| Positioning | Bedrooms |
| Hallways | |
| Landings | |
| Living Rooms | |
| Power Type | Mains Powered (230V) |
| Product Range | FireHawk FHN Series |
| Relative Humidity | Less Than 85% |
| Recyclable | Yes - Valpak's WEEE Distributor Take-back Scheme |
| Sensor Type | Optical |
| Sound Level | 85dB |
| Suitability | Home |
| Warning Type | Audible - Alarm Sounder |
| Warranty | 6 Years |
| Dimensions (Unit) |
|
| Weight | 196g |
| Datasheets |
Please Note: these FHN series alarms are not compatible with the older FH models.
| Product Code | Description | Interlink Type |
| FIFHN250BB | Mains Smoke Alarm with Alkaline Battery Backup | Hardwire Interlink |
| FIFHN450BB | Mains Heat Alarm with Alkaline Battery Backup | Hardwire Interlink |
| FIFHN250RB | Mains Smoke Alarm with Lithium Battery Backup | Hardwire Interlink |
| FIFHN450RB | Mains Heat Alarm with Lithium Battery Backup | Hardwire Interlink |
Excellent and easy to install.
Applies to option(s): Heat Alarm