Every household should install a smoke detector in (almost) every room have. The kitchen is an exception, because here constantly alert by Cooking vapors (fumes) would arise. For little money you can here his life and that the next of kin save, because the first few minutes after the occurrence of fire even lifesaving - then you have no chance.
The mumbi smoke detectors are easy to install and visually interfere in the rooms do not. I hope I never have to hear in action.