Dual-sensor smoke alarm

Photoelectric sensing is faster on smouldering fires; ionisation is faster on fast flaming ones. The research on which matters more has gone back and forth for thirty years, and the honest answer is that a dual-sensor unit removes the question.

The trade is nuisance alarms — the ionisation chamber is more sensitive to cooking — so this belongs on a landing or in a bedroom rather than eight feet from a hob. Sealed ten-year battery, hush button, interlinks with the wireless set on plate 14.

Fitting and care. Keep it well away from cooking — at least ten feet from a hob and out of the direct path between a hob and a doorway. The ionisation chamber makes this the most nuisance-prone alarm in the catalogue and a unit that gets silenced weekly will eventually get taken down. On a landing or in a bedroom it is the best sensing coverage available. Test monthly, vacuum twice a year, never paint. Sealed battery: the whole unit is replaced at end of life.