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

95 Customer Reviews
1 unit 2+ units 5+ units

£9.83 inc VAT

£8.19 ex VAT

£9.59 inc VAT

£7.99 ex VAT

£9.47 inc VAT

£7.89 ex VAT

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: Safelincs Exclusive 5 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



5 Years

Weight 0.23kg
Product Datasheets
FAQs (10)
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.

Q. What smoke alarm should I use in a bedroom with an en suite bathroom?

It is usually recommended to install an optical smoke alarm in a bedroom. This is because optical smoke alarms are slightly quicker at detecting slow smouldering fires that can originate from upholstery type materials and over-heated wiring. Also, an optical smoke alarm would be less likely to sound a false alarm than an ionisation would, if steam/water droplets were present from the bathroom. Detectors should be installed as central to the room as possible; however for your application I would also consider the position of the en suite to make sure that the detector is not in the direct path of the joining door. This is just to try and avoid the chances of a false alarm. No detector is designed for use in bathroom areas.

Q. How do I safely dispose of my old smoke alarms?

Safelincs is signed up to Valpak's WEEE (Waste Electrical and Electronic Equipment) Distributor Take-Back Scheme (Registration ID: 7370). Private households can therefore drop off their electronic and electrical fire safety waste at their municipal recycling centre when they are purchasing new products from us. To find your nearest recycling centre, please visit

Q. How long do the batteries last in smoke alarms?

The 9V alkaline batteries last 12-18 months. Lithium batteries will usually last 5x longer than their alkaline counterparts, achieving around 5 years lifetime. Some lithium cells are also rechargeable, and when used in a mains-powered alarm may last for the entire functional lifespan of the alarm. Newer alarm models may also feature a "sealed" lithium battery. These batteries are specialist components which are designed to not be removed or need replacing by the user, and have been tested by the alarm manufacturer to ensure they last for the lifetime of the alarm.

Please Note: the actual lifetime of your batteries depends on how often the alarms are tested or activated, as sounding the alarm draws more power than when the alarms are "waiting" to detect fire. You should also read your alarm's manual to make sure you only use the recommended types and brands of batteries, as failing to follow these instructions may cause the alarm to malfunction, not alerting you in the event of a fire, and might also invalidate the warranty.

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.

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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

Pricing & Availability

Model Stock 1 unit 2+ units 5+ units
Product Code: FAST625 Stock Level:
More than 20 in stock Expected dispatch: Tomorrow
1 unit

£9.83 inc VAT

£8.19 ex VAT

2+ units

£9.59 inc VAT

£7.99 ex VAT

5+ units

£9.47 inc VAT

£7.89 ex VAT

Delivery Options

The following delivery options are available on this product.

Economy Delivery

£4.79 inc VAT - Orders will be delivered in 3-5 working days by Hermes

Express Delivery

£7.91 inc VAT - Orders will be delivered in 1-2 working days by Hermes

Excellent Warranty

This product is supplied with a 5 year manufacturers warranty as standard

Customer Reviews

95 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: 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

Rating: 5 / 5 Stars

Reviewed by: P C

Easy to install. Not used it...yet!

Published on: 8th October 2019

Rating: 5 / 5 Stars

Reviewed by: J T

Bought. Delivered. Installed.

Published on: 28th July 2019

Rating: 4 / 5 Stars

Reviewed by: C K

Nice size

Published on: 13th June 2019

Rating: 5 / 5 Stars

Reviewed by: S D

Good product It does what it said it would and was delivered promptly with no problems.

Published on: 12th June 2019

Rating: 5 / 5 Stars

Reviewed by: C M

Cuprenol - does what it says on the tin

Published on: 20th May 2019

Rating: 5 / 5 Stars

Reviewed by: C T

neat, compact and aesthetically good.

Published on: 28th April 2019

Rating: 5 / 5 Stars

Reviewed by: I Y


Published on: 20th March 2019

Rating: 5 / 5 Stars

Reviewed by: V B

Brilliant, no more alarms from cooking Very pleased with this alarm in fact I'm considering buying one for my son who's in rented accommodation and the alarm that was in his house has stopped working and you can't replace the battery which is not good so when I've got enough money I'll get one for him Good product

Published on: 4th March 2019

Rating: 5 / 5 Stars

Reviewed by: M C

Very satisfied

Published on: 26th February 2019

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