Huba Pressure switch HC020

The Huba Pressure switch HC020 is a differential air pressure switch used in gas boilers to monitor fan operation and flue gas exhaust. It has a pressure range of 0.8–0.8 mbar and a switching differential of 0.12 mbar. This switch is compatible with specific Vaillant TurboTEC Pro/Plus models (VUW INT 242/3-3, VUW INT 282/3-3, VUW INT 322/3-5, VUW INT 362/3-5), Protherm Gepard 23 KLO, and Saunier Duval Themaclassic Semia. It ensures safe burner operation by confirming airflow before ignition.

When selecting a replacement pressure switch of this type, verify the medium (air or gas), the switching range and differential, and the connection type (threaded or hose spigot). Measure the existing switch's setpoint and differential, and compare with the boiler's requirements. Ensure the electrical rating and approval class match the application. Installation typically involves connecting the impulse tube to the fan or gas train and securing the switch in place.

Common failures include a torn diaphragm, blocked impulse tube, or drifted setpoint, leading to boiler lockouts that may be mistaken for ignition faults. Symptoms include the burner not starting or shutting down during operation. Check the pressure switch for continuity, inspect the impulse tube for blockages, and verify the setpoint with a manometer.