ACV Pressure switch 557A1056

The ACV Pressure switch 557A1056 is a component that monitors air or gas pressure within the burner system. It confirms that the pressure or airflow stays within the permitted band and, if that condition is met, gives the burner control permission to continue the ignition or operation sequence. This pressure switch is compatible with Prestige 75 MK2, HeatMaster 85, and CA 200 Compact models. It is used either as an air pressure switch to prove that the fan is moving air during the pre-purge and running stages, or as a gas pressure switch to guard against minimum or maximum gas pressure.

Parts of this type are selected by the medium (air or gas), the switching range and differential, the type of connection (thread or hose spigot), the contact rating, and the applicable approval class. Before ordering, verify that the switching range and differential match the burner control's required safety settings, and ensure the connection type fits the existing impulse line or pressure tapping.

Typical failures include a torn diaphragm, a blocked impulse tube, or a drifted setpoint. These often show up as lockouts that can be mistaken for ignition problems.