Our house is going on 14-years old, and our smoke alarms have been going off for a few minutes randomly, day or night, but short enough for us to figure out why they're going off. They are First Alert hard wired detectors and I'm gonna replace them with the newer dual detectors that use the ionizing thing along with the photo electric thing. I wanted to add combination CO detector units, but the three detectors inclusive are not available. I have to stick with First Alert as that's the plugs I have hard wired and I'm not gonna change them. I do have First alert tri-gas detectors on each level that detect CO, propane, and natural gas that are plugged into outlets. First Alert recommendations? Please no others as I'm not gonna change the connectors (even though Kidde has some great products, and I know about their adaptors...).