Kromschroder Air pressure switch DL 11K-1 84444874

This is a Kromschroder air pressure switch, model DL 11K-1 (SKU 84444874). It is intended for monitoring positive, negative, and differential pressure of air and flue gases. The switch is used in burner safety circuits to prove airflow before ignition. Its medium pressure range and hand-wheel adjustment allow setting of the required switching point. Connection is made via connection tubes.

Parts of this type are selected by their switching range and differential; verify the markings on the existing switch match the required setpoint. The pressure range (low, medium, high) must cover the application's working pressure. The connection type—hose spigot or threaded port—must fit the impulse line from the fan housing or combustion chamber. The contact rating must be compatible with the burner control's electrical load, and the applicable approval class (gas, oil) should be confirmed before ordering.

Common failure modes include a torn diaphragm, a blocked impulse tube, or a drifted setpoint. When the switch fails to make or break as expected, the burner control unit blocks the ignition sequence and goes into lockout. Because this mimics a flame failure, check the air pressure switch and its impulse line before replacing ignition components.