Sime Air Pressure Switches
The air pressure switch is designed to discover if the fan inside the boiler is rotating and is closely joined to the fan via heat resistant pressure differential tubes which connect to the fan venturies. This permits the pcb to discover whether the fan is functioning since air flow from the fan closes the air pressure switch which then sends a signal to the pcb confirming the fan is functioning. Gas is sent to the burner and at the same time the initialising the comprehensive ignition procedure occurs.
If the fan stops functioning or jams, there'll be too small of air flow throughout this pressure switch which would create the air pressure switch to opperate. This data is then relayed into the printed circuit board instructing that the Sime boiler to stop supplying gas to the burner and to halt the boiler from working. This Sime air pressure switch is a safety device and ensures the safe and secure performance of the boiler.