The LFAS employs a differential pressure to actuate a precision snap switch at chosen pressure setting. This may be the difference between atmospheric and a negative or positive pressure or between any two given pressures. When a change of pressure occurs between the negative pressure chamber and the positive pressure chamber the main diaphragm activates the snap switch at a pre-determined value. Typical Applications: Detects air flow in forced draught appliances Signals either positive, negative or zero air movement Shut down burner in blocked flue conditions Guards against poor or hazardous combustion Indicates dirty or inefficient filters
