Kitchens are where most domestic fires start and the one room where a smoke alarm cannot survive. That is not a contradiction anybody has solved cleverly: the answer is a heat alarm, interlinked with the smoke alarms in the rest of the house, accepting a later warning in exchange for a device that is still on the ceiling in a year.
Why not a smoke alarm
Toasting, frying, grilling and a hot oven all produce enough airborne particles to trigger an optical smoke alarm from across a normal kitchen. An alarm that sounds several times a week gets taken down or has its battery removed, and that is the observed behaviour rather than a theoretical risk. The heat alarm exists because a working later warning beats a removed earlier one.
Where it goes
On the ceiling, away from the wall, and positioned so it is not directly over the hob or the oven where normal cooking heat reaches it. The design standard for dwellings sets minimum distances from walls, light fittings and corners; the principle is that it sits in the space the hot layer will fill in a real fire but not in the plume of a working cooker.
What it will not catch
A slow smouldering fire in a kitchen, for example in a bin or a cupboard, may produce a great deal of smoke before it produces enough heat. That is the recognised limitation. It is another reason the kitchen alarm must be interlinked with the hall and living room smoke alarms, which will pick up smoke drifting out of the kitchen even when the heat alarm has not yet responded.
Open plan kitchens
Where the kitchen is part of a living space with no door, the simple rule breaks down and the design needs thought. Putting a heat alarm over the cooking area and a smoke alarm in the part of the room away from it is the usual approach, with the distance between them chosen so ordinary cooking does not reach the smoke alarm. This is a case where following a diagram written for a separate kitchen produces a bad result.
Questions people ask about kitchen heat alarm
Should a kitchen have a heat alarm or a smoke alarm?
A heat alarm, interlinked with the smoke alarms in the rest of the property. A smoke alarm in a normal kitchen will be triggered by cooking often enough that it gets disabled.
Where should a kitchen heat alarm be positioned?
On the ceiling, away from walls and corners, and not directly above the hob or oven. The design standard for dwellings gives the minimum distances.
What about an open plan kitchen and living room?
Use both: a heat alarm over the cooking area and a smoke alarm in the living part, spaced so that normal cooking does not reach the smoke alarm. The simple separate-kitchen rule does not transfer.