Most homeowners have a smoke detector, at least one, in their home. Ideally, everyone has them in each bedroom, too. But what kind is it, and does it matter?
There are two main types of smoke detectors: ionization and photoelectric. Usually we find ionization types in homes, but the photoelectric is superior. It does cost more, but the photoelectric one will not go off from steam in a laundry room or coming from the bathroom (which makes it tempting to simply remove the battery since it’s an annoyance to get a false alarm!). Additionally, the ionization type responds faster to smoke.
Some home inspectors suggest that it’s a good idea to replace all of the ionazatation types with the photoelectric types for this reason. Interestingly, not everyone shares that opinion. The National Fire Prevention Association suggests using both types in the home (see 2nd article below), noting that each type is better in certain areas of smoke detection. The Allstate insurance blog likewise sees pros and cons in both types, stating that ionization types pick up the smoke from a flaming fire faster (as opposed to a smoldering fire, which apparently is better detected by photoelectric types).