FireAngel Spec+ SP520 Smoke and Heat Alarm

The FireAngel Spec+ SP520 is a mains-powered alarm that combines smoke and heat detection in one unit, with a rechargeable lithium battery that keeps it working for up to 10 years and covers power cuts in between¹. It is a Grade D1 alarm, which is the grade used for domestic mains systems with a backup supply, and it carries a 10-year warranty to match its 10-year lifespan¹.

For a household, that means one unit on the ceiling can respond to both smouldering fires, which produce smoke, and fast, flaming fires, which produce heat, without you having to choose between the two. It is built for open-plan kitchens and living areas, utility rooms and garages, and it links wirelessly to other alarms in the same range so that a warning in one room is heard throughout the building¹.

This page sets out what the SP520 does, what its specifications mean in practice, how to link and test it, what its chirps and flashes are telling you, and how to keep nuisance alarms down. It is a description of one product, not a recommendation over any other.

What the SP520 is and who it suits

The SP520 is a multi-sensor smoke and heat alarm. FireAngel describes it as a Grade D1 alarm combining smoke and Class A1 heat detection, which is the classification used for domestic mains-powered systems with a standby supply¹. In plain terms, it is wired into the household electricity supply, keeps a charged battery in reserve, and watches for two different signs of fire at once.

The smoke side uses an optical sensor, which responds to the larger particles given off by slow, smouldering fires such as a overheated cable or a smouldering sofa. The heat side is Class A1, which responds to a rapid rise in temperature, the signature of a fast, flaming fire such as a chip pan or a waste bin going up. FireAngel's datasheet describes the sensor technology as optical, with UltraSense, Thermoptek and Thermistek technology and Class A1 detection, and a hidden heat cap².

That combination suits the rooms where either kind of fire is plausible and where a single alarm is wanted: open-plan kitchen and living areas, utility rooms and garages. It is not a carbon monoxide alarm. If you have a gas boiler, a solid fuel stove or an open fire, you need a separate CO alarm as well; FireAngel makes a combined smoke, heat and CO unit in the same range, the Spec+ SP540, and a heat and CO unit, the Spec+ SP530. For the general question of which alarm goes where, see Heat Alarm or Smoke Alarm: Which Goes Where.

Specifications at a glance

The figures below are the maker's own, from the SP520 datasheet and product page. They are the ones that decide whether the alarm suits a particular room and installation.

FireAngel also states that the SP520 is tested and certified to EN14604 for domestic smoke detection, and its datasheet lists certification to EN 14604:2005 + AC:2008 and BS 5446-2:2003, with SGS reference PT/25/GEN/0730¹. The maker's product page also refers to BS 5446-2:2003 for domestic heat detection; the two statements describe the same standard for the heat side, and the datasheet gives the fuller certification list¹. For what these standards and grades mean, see Alarm Standards: BS 5839-6, BS EN 50291 and System Grades.

Linking alarms: up to 50 devices by Bluetooth or wire

The SP520 has Bluetooth Low Energy built in as standard, with an optional hardwired connection, so it can be part of a linked system without extra modules¹. FireAngel states that the Spec+ range can interconnect up to 50 alarms wirelessly, giving what it calls a coordinated whole-building response, and that Bluetooth prevents interference or cross-connection with devices outside the network⁴. The datasheet puts the maximum number of connected devices at 50, wired and wireless².

That matters because a fire in a utility room or a garage at the back of the house may not be heard in a bedroom at the front. When alarms are interlinked, one sounding sets the others off, so everyone in the building gets the warning at the same time. The wireless range of up to 35 metres, or more than 120 metres in clear air, is enough for most homes, though walls and floors reduce it².

One point to check before you buy: FireAngel's manuals give different linking limits for different product families. The combined manual for the SP500 to SP540 range states that the FireAngel Bluetooth range is designed to be interlinked with up to 50 products within that range⁴. A separate manual for the FA8620BW, FA8720BW and FA8922BW alarms states a limit of up to 20 products within the range⁷. For how linking works in general, see Interlinked Alarms: How Linking Works and Wireless or Wired Interlinked Alarms.

The Spec+ range also works with dedicated accessories, including the SP565 Hardwired Controller and the SP560 Wireless Controller, according to FireAngel's support pages³.

Testing it and reading the warnings

Test the alarm regularly, and read what it is telling you when it chirps. The SP520 has a quiet self-test that checks the alarm at a volume at least 10dB below full level, so you can test it without disturbing the household; a double-press runs a full 85dB test¹. FireAngel's general guidance on testing frequency is covered in How Often to Test Smoke and CO Alarms.

The indicator light and chirps are the alarm's way of speaking. FireAngel sets out the patterns:

The end of life warning is the one to act on without delay. FireAngel states that when the alarm reaches the end of its life, the yellow LED flashes with 3 chirps every 40 seconds, and the alarm must be replaced within 30 days¹. The 10-year lifespan and 10-year warranty are set to the same clock, so an alarm at end of life is at the end of its cover too¹. For the wider question of when to replace any alarm, see When to Replace a Smoke, Heat or CO Alarm.

The SP520 also has an alarm memory. It lasts 7 days, the LED flashes for the first 3 days, and you press the test button to recall events or hold it to clear the memory¹. That is useful if you come home to a flashing light and want to know whether the alarm sounded while you were out.

Silencing false alarms and quiet nights

Nuisance alarms are the main reason people take batteries out or disconnect alarms, which leaves a home unprotected. The SP520 is designed to reduce them. FireAngel states that the UltraSense dual sensor technology provides fast, accurate detection and reduces nuisance alarms, and that dust compensation reduces nuisance alarms caused by dust buildup in the photoelectric chamber while maintaining smoke alarm performance¹. A bug mesh prevents small insects and debris from triggering the alarm¹.

When an alarm does go off for cooking or steam, the SP520 has a smart silence function. FireAngel states that smart silence allows you to stop an alerting alarm from chirping for 10 minutes¹. Use it to clear the air, not to disable the alarm: the unit returns to normal protection after the period.

For overnight noise, the SP520 has Sleep Easy mode, which FireAngel says stops low battery beeps overnight without compromising smoke or heat protection¹. The alarm also detects low ambient light levels and adjusts its indicators or behaviour during night time hours¹. Both features are there so that a household is not tempted to silence a working alarm at 3am.

Where to fit it, and the Scottish Tolerable Standard

The SP520 is designed for ceiling or wall mounting, and FireAngel lists open-plan kitchen and living areas, utility rooms and garages as suitable locations¹. Its operating temperature of -10°C to +40°C means it can cope with an unheated garage through most UK winters, though a garage that regularly drops below -10°C is outside the maker's stated conditions². Its humidity range of 10% to 95% RH, non-condensing, covers normal UK conditions².

In Scotland, the SP520 is approved for use under the Scottish Tolerable Standard, and FireAngel states that it meets BS 5839-6 requirements for domestic installations¹. The Tolerable Standard is the minimum standard all Scottish housing must meet, and it includes requirements for smoke and heat alarms. If you live in Scotland, or rent out property there, check that the alarms fitted meet it. The rules differ across the UK: for Wales and Northern Ireland, see Wales and Northern Ireland: Alarm Rules and Fire Services, and for the general picture see Smoke Alarms: Types and How to Choose One.

FireAngel's own smoke alarm guide describes its compliant range as covering England, Wales and Scotland, and states that its products carry the BSI Kitemark and are independently certified⁸. The company has been an established UK brand since 1998 and its support is based in Coventry⁸.

The Angel Pro app and alarm memory

The SP520 can report its status through the Angel Pro app. FireAngel's datasheet states that you can extract and share product status and data reporting via the Angel Pro app². That is a way to read what the alarm records and pass it on, for example to a landlord or an installer, rather than a control system for the alarm itself.

The alarm memory is the on-board record. It lasts 7 days, the LED flashes for the first 3 days, and a press of the test button recalls the events, while holding it clears the memory¹. Together, the app and the memory help answer the question every household asks after a disturbance: did the alarm actually go off, and when?

If you have trouble logging in to the app, FireAngel asks you to contact its Customer Support Team on 0330 094 5830⁹. The app is described on FireAngel's FireAngel Pro Connected app page.

Support, warranty and what is in the box

The SP520 comes with the alarm unit, a ceiling base plate, screws and wall plugs, a dust cover already fitted, and the installation and user guide¹. Because it is mains powered, the wiring should be done by a qualified electrician; the maker's installation guide sets out the connections.

FireAngel's customer support specialists are based in the UK and can help with product advice, installation queries and troubleshooting by phone, email or live chat¹⁰. The main number is 0330 094 5830³. FireAngel's technical support also lists an online form at www.fireangeltech.com/support and an email address, technicalsupport@fireangeltech.com, with a separate number for Fire and Rescue customers on 0800 141 2561¹¹. FireAngel also gives a freephone number, 0800 141 2561, for support with alarms fitted by Greater Manchester Fire and Rescue Service and still covered by guarantee¹².

The warranty is 10 years, which FireAngel describes as manufacturer-backed cover for a full decade of protection and support¹. That matches the 10-year lifespan and the 10-year rechargeable battery, so the unit is designed to be installed once and replaced at end of life rather than serviced with new batteries¹.

FireAngel also makes carbon monoxide alarms and water leak and temperature and humidity sensors, which it recommends for full home protection¹³. If you are building a linked system, the FireAngel brand page lists the range, and the Home Emergencies section covers fire, carbon monoxide, gas leaks and burst pipes more broadly.