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Battery Thermally Enhanced Optical Smoke Alarm (Thermoptek) - FireAngel ST-625

Discontinued Product

This product has been discontinued.

alternative product

UltraFire UBS1 Battery Optical Smoke Alarm

  • Battery: 9V alkaline battery (included)
  • Warranty: 10 year warranty
  • Large test and hush button
  • High performance optical sensor
  • Suitable for BS 5839-6: 2019 Grade F2 installations
  • Certified to BS EN 14604: 2005

£8.30 inc VAT

£6.92 ex VAT

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Product Overview

The FireAngel ST-625 smoke alarm uses Thermoptek optical smoke sensing technology; making it thermally enhanced and quicker to detect smouldering fires compared to standard optical smoke alarms. Featuring a large test/hush button, the FireAngel ST-625 has been designed to make silencing and testing your smoke alarm easier.

  • Battery: AA alkaline batteries (included)
  • Warranty: 1 year warranty
  • CE marked and Kitemarked to BS EN 14604
  • Test and hush button feature
  • Thermally enhanced optical smoke sensing technology
  • Less prone to sound falsely from cooking fumes
  • Ideal for areas adjacent to kitchens e.g. downstairs hallway (not suitable for kitchen or garage)
  • Sleep Easy™ function temporarily silences low battery and end of life warning chirp for 8 hours
  • Suitable for installations complying to BS 5839-6: 2019 Grade F2
  • Sensing technology of choice for the UK's Fire and Rescue Service
  • Supplied with fixings; 2 x screws and 2 x rawl plugs
Technical Data
Product Code FAST625
Alternative Product Codes ST-625, ST-625R, st265
Brand FireAngel
Battery Type

2 x AA batteries

Dimensions (HxDia)


Operating Temperature

+4°C to +38°C

Relative Humidity

Up to 90%

Sound Output



1 year

Weight 0.23kg
Product Datasheets
FAQs (3)
Q. Can a smoke alarm be fitted with a sticky adhesive pad in a let property?

The sticky pad is suitable for all battery operated smoke alarms. However, we cannot judge if battery alarms are suitable for your let property, as let properties usually require mains powered alarms. There is some advice to this in the governments guides to fire risk assessments. Also see the LACoRS guide for let properties.

Q. What sort of smoke alarm system would I need to install for a HMO?

BS 5839-6 recommends that one or two storey HMOs with an individual floor area of no more than 200sqm (not the total of both floors) should have a Grade D smoke alarm system installed. Grade D refers to mains powered smoke alarms with a back up battery power supply. The alarms can be interlinked either by wire or by radio signal and the system does not require a separate fire alarm panel. For HMOs of 3 storey or higher, a Grade A panel system would need to be installed. This can cover the whole of the building, or can be used just for the communal areas with a separate Grade D system installed for the individual dwellings. For both applications, the level of cover should be a minimum of LD3 (in all escape routes) but this may change according to the fire risk assessment.

Q. Is the ceiling mounting for the FireAngel 625 identical to that for the FireAngel 620?

The FireAngel 625 smoke alarm uses a different base plate. Therefore it would be necessary to install a fresh base plate if switching from one model to the other.

Key Product Features

Easy-to-use test and hush button central to the alarm

Powered by 2x AA batteries, included with the alarm

Bright status LED shows you that the alarm is powered on

Includes screws and rawl plugs for installation

What's Included?

Every FireAngel FAST625 is supplied with the following components.

  • 1 x FireAngel ST-625 Thermoptek alarm
  • 2 x AA batteries
  • 2 x Screws and rawl plugs
  • 1 x Instruction manual

Customer Reviews

97 customers have given this product an overall rating of 4.7 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: 4 / 5 Stars

Reviewed by: D L

The alarm is working as well as expected but i only installed it 2 months ago.

Published on: 8th March 2022

Rating: 5 / 5 Stars

Reviewed by: E M

Excellent product

Published on: 18th January 2021

Rating: 4 / 5 Stars

Reviewed by: P W

Good solid product. Found that when the base was fitted to the ceiling the outer unit was abit on the tight side to locate and fit but once fitted it was secure enough.

Published on: 16th June 2020

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