Ordinary smoke alarms can only do this one thing
Defending against fire is important, and smoke detectors perform an essential role in keeping your family safe. Even so, smoke detectors have their shortcomings. For example, they are only able to identify smoke, not heat. When there is a fire in your residence, you would not be cautioned unless the smoke ascends to the smoke detector. Even though there are some other significant indications of fire -- including a sudden rise in heat -- if there’s a lack of smoke, you won’t have a warning from your smoke detector.
Additionally, smoke detectors only sound the alarm if they encounter ample smoke. When a fire begins slowly, you may not be warned until the situation is out of hand. Many smoke detectors utilize dual sensors, meaning they will be able to perceive smoke from both roaring flames and smoldering remnants. If they do go off, it’s required of the homeowner to notify emergency services after safely leaving the residence.