The Ei154TL is a Heat Alarm that runs on 230V AC mains power, and has built in tamper proof rechargeable lithium cells that act as a battery back up in the event of mains failure. These rechargeable lithium cells are designed to have a ten year life and outlast the life of the heat alarm itself, whilst providing up to six months of heat alarm operation without mains power. The Ei154TL has advanced features such as the ability to interconnect up to twelve alarms to allow all alarms to sound if just one of the interconnected alarms should be triggered. The Ei154TL has built in circuitry to aid suppression of voltage transients and RF interference to further reduce the chances of false alarms under such conditions. The Ei154TL heat alarm gives a fire warning when the temperature at the unit reaches 580C. Heat alarms are ideal for use in kitchens and garages, where the use of optical or ionisation alarms would lead to unwanted nuisance alarms.