Glow-worm Air Pressure Switches
This pressure switch is designed to discover whether the fan is functioning correctly and is joined to the fan via heat resistant pressure tubes right on the fans venturies. This permits the printed circuit board to discover if the fan is operating since air flow from the fan closes the air pressure switch which then sends a signal to the pcb confirming the fan is operating. At this time gas could be transmitted to the burner and the ignition procedure starts.
If the fan was to quit, jam or stop running there could be too little air flow throughout this atmosphere pressure switch that would create the air pressure switch to start. A signal then is subsequently routed into the printed circuit board instructing that the Glowworm boiler to quit sending gas to the burner and also to turn off the boiler. This Glow-worm air pressure change is a basic safety device ensuring that the secure functioning of the boiler.