Vaillant 0020147866 Pressure Gauge

The Vaillant 0020147866 is a pressure gauge supplied by Vaillant for use in its heating and water heating appliances. It gives a direct dial reading of the pressure inside the appliance or system, so the engineer or user can confirm the unit is sitting within its intended operating range. As a service component it is replaced when the dial no longer reads accurately or the gauge body begins to leak.

• The needle stays at zero or does not move as system pressure changes
• The reading is erratic, jumping or drifting instead of tracking pressure smoothly
• The dial face is clouded, cracked or the scale markings can no longer be read
• Moisture, discolouration or corrosion is visible behind the lens
• There is a weep or leak at the point where the gauge connects to the appliance

• Check the part number 0020147866 against the appliance data badge or the manufacturer's parts listing
• Note the appliance serial number, and the GC number where one is shown, to confirm the correct variant
• Inspect the gauge connection for a sealing washer or O-ring, as these are commonly renewed at the same time as the gauge
• Confirm the fault is with the gauge itself rather than the pressure in the system, since a low reading can also indicate a separate issue