Best Retrofit Smoke Alarms for UK Homes: 2025 Expert Review
Oli at OR Electrics
18th Edition Electrician & Owner
Ensuring your home has working smoke detection is practically the single most important safety step you can take. However, fitting a hard-wired (Grade D) system often involves chasing wires through walls and lifting floorboards—messy work that isn't always feasible for a quick upgrade.
For homeowners looking to retrofit protection without the plaster dust, modern battery-powered (Grade F) alarms have come a long way. They now offer optical sensors that are quicker to detect slow-smouldering fires and less prone to burning the toast false alarms.
In this review, I've selected three retrofit options available in 2025 that I often recommend for quick installations. Whether you need a simple budget replacement or a 10-year sealed unit to avoid the 3am battery chirp, these alarms meet the necessary UK safety standards.
Live in Leeds?
Need a full safety inspection or hard-wired alarm installation?
Get a free quote from our local team.
Specs vs. The Real World
The Spec: "10-Year Battery Life"
"You fit the alarm and forget about it for a decade."
Whilst the battery might last 10 years, dust and spiders don't care. If you don't vacuum the sensor vents regularly, the alarm will fail or false trigger long before the battery dies.
The Spec: "Toast Proof / Less Sensitive"
"You can install it near the kitchen without false alarms."
Optical sensors are better than the old ionisation ones, but they aren't magic. If you burn a steak, smoke is smoke. Position is key—keep it just outside the kitchen, not inside.
My Top 3 Recommendations
Three options to cover different needs and budgets
FireAngel SB1-R Smoke Alarm - Toast Proof, Optical Smoke Alarms
Fireangel
This is a bread-and-butter optical alarm. It's inexpensive, compliant with BS EN14604, and uses standard 9V batteries. It's an ideal choice if you need to fit multiple alarms on a tight budget or need a quick replacement for a spare room.
The Good
- Very affordable entry point
- Standard 9V battery is easy to replace
- Optical sensor reduces false alarms from cooking
The Bad
- Requires annual battery changes
- Not suitable for areas with high steam/moisture
Installer Tip:
Write the date of installation on the side of the alarm with a permanent marker. Smoke alarms have a 10-year total lifespan regardless of the battery—this helps you remember when the whole unit needs binning.
Priced at £7.44 at the time of writing
Check Price on Amazon2 Pack Smoke Alarms for Home – 10-Year Life Fire Alarms with 5-Year Replaceable Battery
TEFLERON
This twin pack offers a step up in build quality with flame-retardant materials and a 5-year battery life, bridging the gap between basic alarms and sealed units. It's an excellent choice for covering both the hallway and landing in a standard two-storey Leeds terrace.
The Good
- 5-year battery reduces maintenance frequency
- Great value for a twin pack
- Flame-retardant ABS construction
The Bad
- Brand is less well-known than FireAngel or Aico
- Slightly bulkier design than some slimline models
Installer Tip:
When fitting these on a landing, ensure they are at least 30cm away from the wall or light fitting. This 'dead air space' ensures smoke actually reaches the sensor during a fire.
Priced at £14.99 at the time of writing
Check Price on AmazonFireAngel Optical Smoke Alarm - FA6620 10-Year Battery Smoke Alarms
Fireangel
The FA6620 is the problem solver for anyone tired of changing batteries or trying to drill new holes in crumbling plaster. It features a sealed 10-year battery and, crucially, fits the baseplates of older FireAngel models (like the ST-622), making upgrades incredibly simple.
The Good
- Sealed battery - no chirping or battery shopping for 10 years
- Retrofit ready: fits existing FireAngel baseplates instantly
- Advanced sensor reduces nuisance alarms significantly
The Bad
- Higher upfront cost per unit
- Whole unit must be replaced when battery dies (though this is standard practice now)
Installer Tip:
If you are replacing an old FireAngel ST-622, you literally just twist the old one off and twist this one on. No drilling required. This is a lifesaver in older properties where plaster can be unpredictable.
Priced at £12.98 at the time of writing
Check Price on AmazonFrequently Asked Questions
Are battery smoke alarms legal in rental properties?
Where should I position a retrofit smoke alarm?
Why does my smoke alarm chirp at night?
Can I replace a mains-powered alarm with a battery one?
How often should I test my smoke alarms?
Need Professional Smoke & Fire Alarm Systems?
Our team at OR Electrics specialises in Smoke & Fire Alarm Systems across Leeds.
Get a free quote for professional installation.
View Our Smoke & Fire Alarm Systems Service