VogelzangPellet Stove Vacuum/Pressure Switch. The vacuum switch is an important safety device thatensures a certain pressure is maintained inside the stove. This switch is mounted on the rear of the unit and will be connected to a plastic or silicon hose. If the switch is damaged or not functioning properly it may cause the feed motor to stopturning, an error code to display or not allow the unit to feedfuel during startup.