Mains Powered Heat Alarm with Alkaline Back-up Battery - Aico Ei144

The Ei 140 series with radio-interlink bases would be suitable for this application:
Ei168RC/141 ionisation: best for landings
Ei168RC/146 optical: best for hallway, living rooms etc
Ei168RC/144 heat detector: best for kitchen and garage
Alternatively the Ei160 series (again with radio-interlink bases):
Ei168RC/161RC ionisation: best for landings
Ei168RC/166RC optical: best for hallway, living rooms etc
Ei168RC/164RC heat detector: best for kitchen and garage
There are also battery operated radio-interlinked smoke alarms available (See Ei3100RF and Ei600RF series)

The manufacturer's recommendation is to test the alarm by pressing the test button. This will simulate a heat input at the heat sensor. You can also test it with a hair dryer but make sure that the hairdryer is kept away at a suitable distance from the alarm. Do not attempt to test the alarm by using open fire or excessive heat as this may damage the unit.

The 9V alkaline batteries and AA alkaline batteries generally last 12 to 18 months. Lithium batteries will usually last 5x longer than their alkaline counterparts, achieving around 5 years lifetime. Some lithium cells are also rechargeable, and when used in a mains-powered alarm may last for the entire functional lifespan of the alarm. Newer alarm models may also feature a "sealed" lithium battery. These batteries are specialist components which are designed to not be removed or need replacing by the user, and have been tested by the alarm manufacturer to ensure they last for the lifetime of the alarm.

Please note: the actual lifetime of your batteries depends on how often the alarms are tested or activated, as sounding the alarm draws more power than when the alarms are "waiting" to detect fire. You should also read your alarm's manual to make sure you only use the recommended types and brands of batteries, as failing to follow these instructions may cause the alarm to malfunction, not alerting you in the event of a fire, and might also invalidate the warranty.

On the side of the smoke alarm locate the removal slot. This is directly above the arrow shown on the smoke alarm face, insert a flat bladed screw driver horizontally approximately 1cm into the removal slot, this will release the fire alarm lock and enable you to push the alarm away from you and will disconnect the alarm from the base plate. This should now expose the battery connected to the alarm enabling you to change the battery. T

To wire the units correctly you would use 2 core and earth cable to the first unit and 3 core and earth to the interconnected units. The alarms do not have to be earthed but a brass screw connector is provided so that the earth can be safety terminated.