Which type of alarm is not effective for fires that do not produce heavy smoke?

Ionization alarms are designed to sense the presence of smoke particles in the air, particularly those generated by flaming fires that produce a significant amount of smoke. However, these alarms may not be effective in detecting fires that smolder and produce little to no smoke, as they rely on the ionization of air molecules that occurs when smoke particles enter the sensor.

In contrast, heat detectors respond to changes in temperature and are effective in detecting any type of fire that significantly raises the ambient temperature, even if it does not produce heavy smoke. Smoke detectors are specifically designed to identify smoke from various types of fires, including smoldering ones, making them more effective in those scenarios.

This distinction highlights why heat detectors and smoke detectors can provide better coverage for different types of fire scenarios compared to ionization alarms alone, particularly in situations where smoke is minimal. Thus, ionization alarms may not respond to certain types of fires, particularly those that lack heavy smoke, making them less reliable for those specific circumstances.