Abstract: A smoke detecting system monitors smoke from different monitored areas. A main system fan is energized to draw air from all the monitored areas through a smoke detecting unit via individual pipes and via a location unit. When smoke is detected, a control unit produces an indication. In addition, it energizes a sequencing unit which switches off the main fan and then sequentially and individually energizes small fans, each of which draws air through a respective one of the individual pipes and feeds it through the smoke detection unit. When the small fan corresponding to the pipe connected to the particular one of the monitored areas from where the smoke originates is energized, there will be an increase in the output of the smoke detector. This is detected by the control unit which causes the sequencing unit to identify this monitored area on an indicator.