We want to fix a smoke alarm in our house so any body tell me about the quality of smoke alarm?

Yes this will save your life. To hell with the house. When this burns insurance pays up. Put them close enough all thru the house. In a geological fault area put carbon monoxide detectors.
I was air quality for many businesses before retirement. I have had friends die from being exposed to carbon monoxide. Others dead from defective sensors or dead batteries they could have changed and not left me on the world alone.
Use you tube and listen to them chat about the idea of something watching over you while you sleep alone in the dark.