Most new smoke detectors are photoelectric rather than ionisation-based these days because China can pump basic models out for $2-3 shipped in quantity one. (In

Most new smoke detectors are photoelectric rather than ionisation-based these days because China can pump basic models out for $2-3 shipped in quantity one. (In fact, the cheapest I've heard of them going for is £1 for a two-pack in a UK discount store recently.) Nest got a bunch of flack because apparently they screwed up their original single-wavelength implementation and had obnoxious problems with false alarms.