Regular smoke alarms can only do this one thing
Protecting your home from fire is important, and smoke detectors take on a vital role in keeping your family safe. Despite that fact, smoke detectors have various drawbacks. For example, they can only detect smoke, not heat. If there is a fire in your house, you may not be alerted until the smoke ascends to the smoke detector. While there are some other unmistakable signs of fire -- including a sudden rise in heat -- if there's no smoke, you won’t have a sounding of your smoke detector.
Additionally, smoke detectors only sound the alarm if they find an adequate amount of smoke. In the event a fire begins slowly, you may not be alerted until it's too late. Many smoke detectors employ dual sensors, which means they will recognize smoke from both a raging fire and something less intense. Then when they start beeping, it's up to the occupant to contact the fire department after exiting the property.