Halstead Air Pressure Switches
Air pressure switches are installed into a boiler to detect the operation of the fan and is joined to the fan via heat resistant pressure tubes directly on the fan venturies. This enables the printed circuit board to discover when the fan is spinning since air flow from the fan closes the air pressure switch which in turn sends a signal to the printed circuit board confirming the fan is running. At this time gas can be transmitted to the burner and the ignition procedure can begin.
If the fan was quit or stop, there could be a lack of air flow across this air pressure switch that would create the air pressure switch to open. A signal is then sent to the printed circuit board instructing that the Halstead boiler to stop sending gas to the burner and also to turn the boiler off. This Halstead air pressure switch is a basic safety device ensuring the safe running of the boiler.