Quick comparison
| Model | Price (UK) | BS 5839-6 grade | Best for | App/remote alerts |
|---|---|---|---|---|
| Aico Ei3016 | £45–£60 | Grade D1 | New builds and electricians | Optional — via Ei1000G gateway (cloud) |
| Kidde FireX Mains (KF20) | £20–£30 | Grade D | Budget mains installs | No |
| X-Sense SD19-W | £25–£35 | Grade F | Wireless interlink without rewiring | No |
| Bosch Smart Home Smoke Detector II | £55–£70 | Grade F | Bosch ecosystem users | Yes — Zigbee via Bosch hub |
How we chose these smoke detectors
We picked alarms currently sold in the UK that meet BS EN 14604, interlink with other units, and either reach BS 5839-6 Grade D or give you remote alerts. We checked manufacturer specifications and UK retailer prices in October 2026. We have not lab-tested every unit.
UK Regulations: What the Law Requires
BS 5839-6 is the key standard. This British Standard covers the design, installation, commissioning and maintenance of fire detection and fire alarm systems in domestic premises. For most homeowners the relevant grade is Grade D — a network of interconnected, mains-powered smoke alarms with integral battery backup. New builds and material alterations must meet this minimum under Building Regulations Approved Document B (fire safety). The category LD2 placement requirement means at least one detector in every circulation space (hallways and landings) plus high-risk rooms. Scotland has its own stricter regime: since 1 February 2022 every home must have interlinked alarms — one smoke alarm in the living room or the room you use most, one in every hallway and landing, and a heat alarm in the kitchen — plus a carbon monoxide alarm wherever there is a fuel-burning appliance. In Scotland the responsibility sits with the property owner.
For existing homes without rewiring, Grade F (battery-only, interlinked by radio) is still permitted under BS 5839-6, and the modern 10-year sealed-battery alarms in this guide meet that grade comfortably. If you are doing any renovation that involves electrical first-fix work, upgrading to Grade D mains units is strongly advised.
Landlords in England must fit at least one working smoke alarm on every storey of a rented property under the Smoke and Carbon Monoxide Alarm (England) Regulations 2015, amended with effect from 1 October 2022 to require a CO alarm in any room used as living accommodation that contains a fixed combustion appliance (gas cookers excepted), not just solid fuel. Alarms must be tested at the start of every new tenancy, and where a local authority finds a breach it can issue a remedial notice and a civil penalty of up to £5,000. Wales applies equivalent requirements under the Renting Homes (Wales) Act 2016, and Scottish landlords must meet the same national standard that applies to owner-occupiers.
Your local Fire & Rescue Service can advise on siting. Note that BS 5839-6 is a code of practice: the legal duties come from Building Regulations and the landlord rules above.
Smart vs Standard Smoke Detectors
The core difference is connectivity. A standard alarm sounds locally and nothing else. A smart alarm adds one or more of: Wi-Fi or Zigbee connectivity for remote notifications, voice announcements that tell you which room is affected, integration with smart home platforms, and — in some cases — combined carbon monoxide detection. The trade-off is cost (smart units typically run from around £25 to £70 each now that the premium Nest Protect has gone) and, for Wi-Fi models, reliance on a working internet connection. For a broader overview of building out your security setup, see our guide to the best smart doorbells in the UK.
Top 4 Smart Smoke Detectors for UK Homes
1. Aico Ei3016 — Best for New Builds and Electricians
Pros: 230 V mains with 10-year lithium rechargeable backup; Grade D1 compliant; wireless interlink via the optional Ei3000MRF SmartLINK module; AudioLINK+ data extraction to smartphone; 85 dB(A) sounder; 10-year guarantee. Cons: No Wi-Fi or cloud app in the base unit; the radio module (about £85 ex VAT) and the optional Ei1000G gateway (roughly £180–£230) are extra; less polished consumer packaging than Nest.
Priced at roughly £45–£60 per alarm at UK trade suppliers such as Safelincs, Aico's Ei3016 is the alarm of choice for UK electricians fitting new builds and refurbishments to BS 5839-6 Grade D1. It uses optical detection and can interlink wirelessly with the wider Aico 3000 series — smoke, heat and CO alarms — without any additional cabling. Aico is the consumer-facing brand of Ei Electronics, so you will see the same alarms listed under either name; see the Home Assistant section below for how to bring them into your smart home. The AudioLINK+ feature lets you pull a diagnostics report directly from the sounder using a smartphone app, which is genuinely useful during annual testing. Find the Aico Ei3016 on Amazon UK.
2. Kidde FireX Mains (KF20) — Best Budget Mains Alarm
Pros: 230 V mains with 9 V alkaline battery backup; optical detection; hard-wired interlink with up to 23 Firex alarms; BSI certified to BS EN 14604:2005; test/hush button; meets Grade D BS 5839-6. Cons: No wireless interlink or app connectivity; alkaline backup battery (not sealed); basic feature set.
The Kidde FireX KF20 is a no-frills workhorse that ticks all the regulatory boxes for new builds at a considerably lower price per unit than Nest or Aico. It hard-wires to up to 23 other Firex alarms so that all units trigger simultaneously. If you want mains-grade protection without the premium, this is the practical choice — especially for landlords fitting multi-room systems, where the Smoke and Carbon Monoxide Alarm (England) Regulations 2015 make per-unit cost a real factor across a portfolio. Find Kidde FireX Mains on Amazon UK.
3. X-Sense SD19-W — Best for Wireless Interlink Without Rewiring
Pros: 10-year sealed battery; wireless interlink of up to 24 units; 250 m open-air transmission range; photoelectric sensor; self-test every 60 seconds; very competitive price per unit. Cons: No Wi-Fi or app remote notifications; no CO detection; battery-only so Grade F rather than Grade D.
The X-Sense SD19-W fills a practical gap for homeowners who need a properly interlinked system throughout a large house but cannot or do not want to run new mains wiring. Up to 24 units communicate wirelessly — when one triggers, all sound. The 10-year sealed battery means no annual battery replacement faff. Note this is a Grade F system under BS 5839-6, which is acceptable for existing dwellings but not for new builds or major refurbishments. See X-Sense SD19-W at xsense.com or find it on Amazon UK.
4. Bosch Smart Home Smoke Detector II — Best for Bosch Ecosystem Users
Pros: Zigbee 3.0 connectivity; app push notifications via Bosch Smart Home app; networks with other Bosch Smart Home smoke alarms (all sound simultaneously); contamination compensation to reduce false alarms; replaceable 3 V lithium battery (up to 5 years). Cons: Requires Bosch Smart Home Controller (sold separately); no Amazon Alexa or Google Home integration; battery-only power supply; higher cost than X-Sense for similar detection capability.
If you already run a Bosch Smart Home setup, the Smoke Detector II integrates neatly — it uses Zigbee 3.0 and sends push notifications with room location via the Bosch app. Multiple units network together for simultaneous alarm activation. It does not currently integrate with Amazon Alexa or Google Home, and Home Assistant's Bosch SHC integration, which runs locally through the Smart Home Controller, does not list smoke detectors among its documented device types, so check before relying on it for automations. Find Bosch Smart Home Smoke Detector II on Amazon UK.
Mains-powered or 10-year sealed battery: which should you choose?
Mains alarms with battery backup suit new builds and rewires; 10-year sealed-battery alarms suit existing homes. Both types must meet BS EN 14604, the product standard for smoke alarm devices. A mains unit (Grade D under BS 5839-6) needs an electrician and is hard-wired to the lighting circuit, while a sealed-battery unit (Grade F) fixes to the ceiling with two screws and links to its neighbours by radio. Neither is more sensitive; the difference is installation effort and what happens at the end of life.
| Factor | Mains with battery backup (Grade D) | 10-year sealed battery (Grade F) |
|---|---|---|
| Installation | Electrician, wired circuit | DIY, screws to ceiling |
| Interlink | Wired or radio | Radio only |
| Power failure | Backup battery takes over | Unaffected |
| Replacement | Replace unit at end of life | Replace whole unit after about 10 years |
| Best for | New builds, rewires, landlords with electrical work scheduled | Existing homes and rentals without rewiring |
Which smart smoke detectors work with Home Assistant and Matter?
Only Bosch has an official Home Assistant integration among our four picks. The Bosch Smart Home Smoke Detector II is supported through Home Assistant's Bosch SHC integration, while Aico alarms rely on a community integration via the Ei1000G gateway, and the Kidde and X-Sense units have no smart link at all. We found no Matter certification for any of the four at the time of writing, so check the box or manufacturer page before buying if Matter matters to you.
| Model | Remote alerts | Home Assistant | Interlink |
|---|---|---|---|
| Aico Ei3016 | Via Ei1000G gateway | Community integration (HomeLINK) | Wired or Aico radio |
| Kidde FireX Mains (KF20) | No | No | Wired |
| X-Sense SD19-W | No | No | Radio |
| Bosch Smart Home Smoke Detector II | Yes, via Bosch hub | Official (Bosch SHC) | Radio via Bosch system |
Do I also need a heat alarm in the kitchen?
In Scotland, yes: the national standard requires a heat alarm in the kitchen alongside smoke alarms in the living room, hallways and landings. Elsewhere in the UK it is good practice rather than law, because a smoke alarm next to a cooker triggers false alarms from toast and steam. Heat alarms must be interlinked with your smoke alarms from the same family, so check compatibility before mixing brands.
Interconnection Options
Wired interlink (used by Kidde FireX and Aico in hard-wired mode) carries a trigger signal along a dedicated wire — reliable and requires no RF spectrum. Wireless/RF interlink (Aico RadioLINK, X-Sense SD19-W) eliminates cabling and is ideal for retrofits. Wi-Fi/app interconnection (Nest Protect, Bosch) works differently — it's cloud-mediated, meaning remote notifications depend on your broadband being live. For life-safety purposes, any of the three wired or RF approaches is preferable to cloud-only interconnection.
Carbon Monoxide Detection
None of the four picks combines smoke and CO sensing, and with the Nest Protect gone there is no widely sold combined smart unit in the UK. CO is odourless and kills quickly, so if you have a gas boiler, gas fire or open fire, fit a dedicated CO alarm in each room with a fuel-burning appliance — in England landlords are legally required to. Our best smart carbon monoxide detector guide covers the options. BS 5839-6 does not mandate CO detection but references BS EN 50292 for placement guidance. For advice on layering detection devices, see our smart home starter guide for the UK.
What happened to the Google Nest Protect?
Google stopped making the Nest Protect in March 2025, and it has not been replaced in the UK. Existing units keep working and Google has said they will continue to receive support and software updates, but new stock is scarce and the First Alert-built successor Google announced is for the US and Canada only. We have removed it from our ranked picks for that reason. If you already own Protects, keep them: they still alert through the Google Home app. If you are buying new, choose from the alarms above and add a separate CO alarm.
Do Aico and Ei alarms work with Home Assistant?
Yes, but only through Aico's cloud and a gateway. The Ei1000G SmartLINK gateway (roughly £180–£230) reports alarm events from interlinked Aico and Ei Electronics 1000 and 3000 series alarms to the HomeLINK/SmartLINK portal, and a community-maintained HACS custom integration, AICO HomeLINK, reads that data into Home Assistant as binary sensors, device status and events. Its author lists the Ei3014, Ei3016, Ei3028, Ei3030, Ei1025 and Ei450 as working. It needs a HomeLINK account with Landlord access, is cloud-based rather than local, and is not an official Home Assistant integration, so treat it as a convenience layer: the alarms themselves interlink and sound without it. Never rely on Home Assistant or a cloud service as the thing that wakes you up.
App Alerts and Smart Home Integration
Remote alerts are now the weak spot of the category. The Aico Ei3016 with an Ei1000G gateway offers the most professional route, with portal and app reporting. The Bosch Smart Home Smoke Detector II sends push notifications through the Bosch app over Zigbee but is limited to that ecosystem. FireAngel's Pro Connected range, which pairs a hub with the FireAngel Connected app, is another connected route, though several older FireAngel models have been discontinued so check stock before committing. We did not find a current Hive smoke alarm to include. X-Sense SD19-W and Kidde FireX have no app integration. Whichever you choose, the local interlink is what protects you; app alerts are a bonus.
Installation and Maintenance Costs
Battery-only units (X-Sense, Bosch) are the cheapest to install — no electrician required, and fitting is a five-minute job with a screwdriver. Mains-wired units (Aico, Kidde FireX) need a qualified electrician for first-fix cabling, typically adding £150–£300 in labour per property for a whole-house interlinked system, though this is usually only relevant during a rewire or new build rather than a retrofit. Ongoing costs are modest: 10-year sealed-battery models (Aico, X-Sense) need no maintenance beyond an annual test-button check, while Kidde's replaceable 9 V backup battery should be swapped yearly. All alarms should be replaced entirely at the 10-year mark regardless of battery type, as the smoke sensor chamber itself degrades.
Verdict
For new builds, rewires and anyone who wants app reporting, the Aico Ei3016 is the most complete Grade D1 solution: professional grade, 10-year guaranteed, radio-interlinkable and cloud-reportable through the Ei1000G gateway. Renters and homeowners who cannot rewire will find the X-Sense SD19-W the most cost-effective whole-house wireless interlink. The Kidde FireX KF20 is the sensible budget option for mains-wired installs, and the Bosch Smart Home Smoke Detector II earns its place only if you already run Bosch Smart Home. Google Nest Protect is no longer recommended for new purchases. Pair any of these with a separate CO alarm, and if you are building a Home Assistant dashboard around your alarms, see our Home Assistant alarm panel guide.
Related: best smart carbon monoxide detector, best home security system UK, and smart home security tips.
