The Complete Alarm Sensor Decision Guide (2026)

Fire alarms have different sensors to detect different fire types. Some alarm sensors react to heat, and some to the physical smoke created by a fire. By fitting the right type of alarm sensor, you will avoid nuisance alarms and get the best protection.

Here is our guide to choosing the right types of alarm systems for each area within a property. 

Which alarm sensor goes where?

The two houses below show rooms that are colour-coded to show which sensor types are best suited to each area of a typical property.

Kitchen

A heat alarm is best for the kitchen because it’s immune to activating as a result of steam and cooking fumes. Unlike smoke alarms, it won’t trigger false alarms from everyday activities like boiling water or frying food.

Bedroom

In bedrooms, a multi-sensor fire (optical and heat) or optical smoke alarm is recommended. These alarms are highly sensitive to smouldering fires, which are the most common type to occur while people are sleeping (due to the ignition of soft furnishing), giving you early warning when it matters most.

Hallway or Landing

For hallways and landings, install a multi-sensor fire alarm (optical and heat) or an optical smoke alarm. These areas act as natural passageways for smoke, and a multi-sensor device can quickly detect smoke movement between rooms, ensuring faster alerts for the whole home.

Living Room

A multi-sensor fire (optical and heat) works best in living rooms. These alarms are ideal for fires which result in the ignition of soft furnishing and electrical equipment, providing reliable protection in the spaces you spend most of your time.

Garage, Loft, or Utility Room

In garages, lofts, or utility spaces, choose a multi-sensor fire (optical and heat) alarm. These alarms are designed to work in dusty or fume-filled environments. The sensors in the fire multisensor alarms work together to reduce the chances of false activations. 

Near the Boiler or Fireplace

Install a carbon monoxide alarm between 1 and 3 metres from any boiler or fireplace. These alarms detect harmful gas leaks early, alerting you before carbon monoxide levels become dangerous and helping protect against a serious, invisible threat.

This quick room alarm guide is your starting point. From here, we’ll show you why each choice matters and how to place it for maximum effectiveness.

Choosing Alarm Sensor Types 

Different rooms behave differently. The goal isn’t one sensor everywhere; it’s to design an alarm system that matches room use and environment.

Using the correct combination helps reduce false alarms, shortens response time, and ensures your alarms only trigger when real danger is present.

Understanding the Types of Fire Alarm Sensors

1. Multi-Sensor Fire Alarm

• Combines optical + heat sensors.
  
• Both sensors work together to analyse both components before sounding
• Ideal in bedrooms, hallways, and living rooms where mixed fire types may occur.
• Great choice when you want to avoid nuisance alarms.

Why choose a multi-sensor fire alarm: All-rounder protection; works well in most UK homes.

We recommend the Mains Powered Multi-Sensor Fire Alarm – Ei3024

2. Optical Smoke Alarm Sensor

• Detects visible smoke particles from slow-burning fires (upholstery, cables).
  
• Performs best in living rooms and bedrooms.
  
• Avoid installing near kitchens or bathrooms – steam may trigger an alarm unnecessarily.

Why choose an optical smoke alarm sensor: Sensitive, stable, and perfect for clean, low-humidity rooms.

We recommend the Mains Powered Optical Smoke Alarm – Ei3016

3. Heat Sensors

• Measures temperature rather than smoke.
  
• Heat alarms are only suitable for kitchens and garages.
  
• Completely nuisance-causing from cooking aerosols or dust.
  

Why choose a heat sensor: Prevents false alarms and reacts to fast-flaming fires. 

We recommend the Mains Powered Heat Alarm – Ei3014

4. Carbon Monoxide Alarms

• Detects CO gas from any fuel-burning appliance.
  
• Not a smoke detector replacement – an essential add-on.
  
• Mount near any fuel-burning appliance for complete coverage.

5. Interconnected Alarm Systems

Regardless of the house alarm type, alarms should be interconnected throughout a property to ensure all alarms sound in the event of an activation, providing audibility for the occupants. Where hardwiring is not possible, use RadioLINK technology to interconnect wirelessly using radio frequency signals to reduce the time and disruption of running cables between the alarms

Optical vs Heat vs Multi-Sensor (Quick Comparison)

Multi-Sensor Alarms

• Detect smoke particles
• Detect temperature rise
• Sometimes suitable for open-plan kitchens and dining spaces
  
• Works well in bedrooms,  living rooms, and hallways/landings.
• Best overall at preventing false alarms
• Respond to different fire types

Optical Alarms

• Detect smoke particles
• Do not detect temperature rise
• Not suitable for kitchens
• Ideal for bedrooms,  living rooms and hallways/ landings
  
• Good at preventing false alarms
• Limited response to different fire types

Heat Alarms

• Do not detect smoke particles
• Detect temperature rise
• Suitable for kitchens or garages
• Not suitable for bedrooms or hallways/ landings
• Help prevent false alarms in kitchens
• Limited response to different fire types

Takeaway:

Use fire alarms as the default; pair with heat in kitchens and optical in sleeping areas for the best balance of sensitivity and stability.

Building an interconnected alarm system with Aico

Aico’s range lets you combine heat, optical, and multi-sensor alarms into a fully interlinked network via SmartLINK or RadioLINK+.

When any device detects smoke or heat, it instantly activates every connected alarm – providing whole-home coverage and complete confidence.

Summary Checklist

• Kitchen = Heat alarm
• Bedroom = Optical or Multi-sensor
• Living room = Multi-sensor
• Hallway = Multi-sensor
• Garage = Heat alarm
• CO near boilers or fires
• Interlink and test monthly

Choosing the right sensor type is how you avoid nuisance alarms and protect every corner of your home.