Multi-sensor fire detectors combine two or more sensing methods in one device. Also, most use an optical sensor for smoke and a thermal sensor for heat. A built-in processor compares both signals before it decides on an alarm.
This approach reacts to more types of fire and reduces nuisance alarms. In this guide, we explain how multi-sensor fire detectors work, what they offer and where they fit best.
How do multi-sensor fire detectors work?
A multi-sensor detector contains several sensors that watch different fire signs. Some also include a carbon monoxide sensor. The detector reads all signals and applies an algorithm.
For example, a rise in smoke together with a rise in temperature points to a real fire. Also, smoke alone from a toaster or steam from a shower is less convincing. The detector can then wait, or raise a lower-level warning. As a result, the system reacts quickly to real fires and ignores many false triggers.
Optical, heat and multi-sensor detectors compared
| Detector | Best at | Weak at |
|---|---|---|
| Optical smoke | Smouldering fires with visible smoke | Fast flaming fires without much smoke; steam and dust can cause false alarms |
| Heat | Dusty, steamy or smoky areas with fast temperature rise | Slow, smouldering fires |
| Multi-sensor | A wide range of fires, with fewer false alarms | Cost per detector is higher than a single sensor type |
European standards cover these detectors. Also, eN 54-7 applies to point smoke detectors and EN 54-5 to heat detectors. Newer parts of the series cover combined smoke and heat detectors.
Where do multi-sensor fire detectors help most?
- Hotels and student housing, where cooking and showers cause nuisance alarms.
- Kitchens, canteens and plant rooms with steam and heat.
- Hospitals and care homes, where false alarms disrupt patients and staff.
- Offices and retail that want one detector type across the building.
Explore our pages for healthcare and retail to see how detection fits these environments.
Tips for choosing and placing multi-sensor detectors
- Match the detector to the room. Check the data sheet for the recommended use.
- Follow spacing rules. EN 54-14 and local codes set the coverage per detector and the mounting height.
- Use compatible bases and panels. Detectors must work with your panel and loop protocol.
- Avoid direct airflow and heat sources. Keep detectors clear of vents and ovens.
- Plan cleaning and testing. Dust slowly changes sensitivity, so service them regularly.
Addressable systems can also report the contamination level of each detector. Therefore, engineers clean only the devices that need it.
Multi-sensor detectors in our systems
The Kidde Commercial Excellence series includes intelligent addressable detectors with combined sensing. Also, see the addressable fire detection page. For simpler sites, our conventional fire detection page lists conventional options. If you need very early warning in a clean room, read about aspirating smoke detection.
Key takeaways
- Multi-sensor fire detectors combine smoke and heat sensing in one device.
- They react to more types of fire and cut nuisance alarms.
- Match the detector to the room and follow EN 54-14 spacing rules.
- Check that multi-sensor fire detectors are compatible with your panel.
Frequently asked questions
Are multi-sensor fire detectors better than optical detectors?
They suit more situations because they react to smoke and heat. Optical detectors still work well in many clean areas, so the best choice depends on the room.
Do multi-sensor detectors cost more?
The detector costs more than a single-sensor model. However, fewer false alarms and simpler design can lower the total cost over time.
Do they work with every fire alarm panel?
No. A detector must be compatible with the panel and the loop protocol, so always check compatibility before you order.
For basic background, read this overview of fire detection.