Vaillant Flow Switch 151041

The Vaillant 151041 is a flow switch, also listed as a pressure differential switch, used on Vaillant Thermocompact VU and Turbomax VUW gas boilers. It monitors water flow through the appliance and signals the control board so the boiler can respond to a demand. It sits within the pressure relief and safety valve group of gas boiler spares.

• The boiler does not fire on a hot water or heating demand even though the pump runs
• Burner ignition is intermittent, with the appliance dropping out shortly after start-up
• The boiler locks out or shows a fault when flow is present at the taps
• Domestic hot water runs cold or fluctuates while the appliance otherwise operates normally
• The switch shows signs of scale, debris or mechanical wear when inspected

• Confirm your appliance model against the fit list above, as the same part number covers several VU and VUW variants
• Check the existing switch is marked 151041, or that the manufacturer's parts list for your model specifies this number
• Verify the fault is traced to the flow switch rather than the pump, diverter valve or control board
• Have the appliance model and GC number to hand when checking compatibility