Vaillant Impeller Aqua Sensor 194830

The Vaillant 194830 is a complete impeller assembly with an integrated aqua sensor, used on Vaillant Ecomax 200 and Ecomax 828/2E VUW 286/2 C gas boilers. The impeller sits in the domestic hot water circuit and rotates as water is drawn, while the aqua sensor registers that flow and signals the boiler to fire for hot water demand. It is supplied as a complete unit rather than as separate components.

• The boiler does not fire when a hot water tap is opened, despite a clear draw of water.
• Hot water demand is detected intermittently, giving inconsistent or delayed firing.
• The impeller is stiff, seized or visibly worn, or does not spin freely in the water flow.
• Scale, sludge or debris has collected around the impeller and sensor, affecting flow detection.
• Flow-related fault behaviour on the domestic hot water side that points to the aqua sensor circuit.

• Confirm the boiler model and variant against the fitment list above, as the same appliance family uses more than one configuration.
• Check the existing impeller and sensor assembly for the part number marking before ordering.
• Inspect the surrounding housing and seals for scale or damage, as these can affect the new assembly once fitted.
• Isolate the appliance and its water supply before starting any work, and follow the manufacturer's instructions for the appliance.