Main Heater Air Pressure Switch (Aps)

The air pressure switch facilitates safety checks which ensure the fan is working correctly. It ensures that, if the fan fails within the boiler, there would not be a build up of toxic gasses with no means of venting them. The PCB closely monitors the air pressure switch to make sure it is fully operational before the unit is fired up, preventing the appliance from starting without one of its key safety instruments.