Unfortunately, every homeowner is required by law to have working smoke and carbon monoxide detectors. We wonder how many actually change the batteries regularly. We sympathize with the ones who don’t, because (a) they are on the ceiling (or up high on the wall) so you have to climb onto a ladder or stool and stand perilously, (b) even the best-organized homeowner is likely to have a mixture of makes and models of these detectors so the ladder-climber may have to guess whether the detector is removed and replaced by turning clockwise or counter-clockwise, and (c) when s/he tests the detector the sound is deafening.