Perhaps as a PSA, I wanted to point out that there are two types of smoke detector technologies: ionization and photoelectric. Ionization detectors are more s

Perhaps as a PSA, I wanted to point out that there are two types of smoke detector technologies: ionization and photoelectric. Ionization detectors are more sensitive to flaming fires. Photoelectric are more sensitive to smoldering fires. As my friend whose house had an in-wall smoldering fire for four hours before the ionization alarms went off now knows, it's important to have both types of smoke detectors throughout your house. The Nest appears to only be a photoelectric smoke detector based on a quick googling right now. In my house, I have 5 photoelectric alarms that are hooked up to my central alarm system that is centrally monitored. I also have 4 ionization alarms that are hard wired together such that if one goes off they all go off. The ionization are not hooked up to the central alarm system because they have a reputation of having more false alarms. I have never experienced a false alarm in 5 years, but that is their reputation so many experts recommend not making them hooked up to a system that alerts a central monitoring service. More Info: http://www.nfpa.org/safety-information/for-consumers/fire-and-safety-equipment/smoke-alarms/ionization-vs-photoelectric http://www.nfpa.org/safety-information/for-consumers/fire-an...