Some insurers offer a 5 percent discount if your home has smoke alarms. Install both types of smoke sensors and a CO alarm on every level and a smoke alarm in the attic and in all bedrooms and hallways. Our top picks focus on interconnecting models. Here's what else to consider:
Hardwired systems tie into a home's wiring and require professional installation (about $250 per unit). Battery-only alarms and plug-in CO alarms are easy do-it-yourself projects.
Smoke alarms should have a hush button, safer than disabling the alarm by removing the power during a false alarm. On CO alarms, look for a digital display showing CO levels in parts per million; levels as low as 30 ppm can harm heart patients, pregnant women, and children. Some show peak levels that occurred while you were out.
First Alert's SCO501CN and Kidde's KN-COSM-1B combine CO and smoke detection. But each covers only one type of fire and, like all CO alarms, should be replaced every five years; smoke alarms, every 10 years.