Description
The Mercury is a heat alarm with an internal thermistor sensor that detects rapid temperature rises between 54°C and 70°C, triggering an 85dB alert at 3m when activated. Unlike smoke alarms, the thermistor responds to temperature rather than airborne particles, making it suitable for kitchens, garages, utility rooms and lofts where cooking fumes, steam or dust would trigger false alarms on a standard smoke detector.
The alarm runs on a sealed internal 3V lithium battery rated for 10 years of continuous operation, removing the need for annual battery replacement. A low battery warning sounds when the unit approaches end-of-life, at which point the entire alarm is replaced. The 116mm diameter white housing mounts to ceiling or wall surfaces using the two-screw fixing points in the base, and the battery activates via a switch on the back once the alarm is installed.
A mute function disables the alarm for nine minutes if triggered by a non-emergency temperature rise, allowing time for the room to cool before the sensor resets automatically. The alarm is tested to BS 5446-2:2003 for heat alarms in domestic properties in England and Wales, but does not meet the interlinked alarm requirements introduced in Scotland under 2022 regulations. The 116g weight and 46mm height allow ceiling mounting on standard plasterboard with typical fixing plugs.
Specification
| Batteries |
DC3V lithium battery (internal) |
| Alarm output |
85dB @ 3m |
| Sensor |
Electronic thermistor |
| Alarm level |
54°~70°C |
| Lifetime |
10 years |
| Dimensions |
116mm Φ, 46mm height |
| Weight |
0.12KG |
Downloads
Product Manual
Frequently Asked
Where should a heat alarm be installed?
Heat alarms are designed for kitchens, garages, utility rooms and lofts where smoke alarms would false-trigger on cooking fumes, steam, dust or exhaust. They detect rapid temperature rises rather than airborne particles. For bedrooms, hallways and living spaces a smoke alarm is required.
Does the battery need replacing?
No. The internal 3V lithium battery is sealed and rated for 10 years. When the low battery warning sounds near end-of-life, the entire alarm unit is replaced rather than changing the battery.
Is it suitable for Scottish homes?
This alarm does not meet the interlinked alarm requirements introduced in Scotland under 2022 fire safety regulations. It is tested to BS 5446-2:2003 and is suitable for homes in England and Wales.
What temperature triggers the alarm?
The thermistor sensor triggers between 54°C and 70°C when it detects a rapid rise in ambient temperature. The nine-minute mute function allows the alarm to be temporarily disabled if triggered by non-emergency heat.