Vaillant 101271 Pressure gauge

The Vaillant 101271 is a pressure gauge supplied by Vaillant as a replacement component for its heating appliances. It sits within the unit and gives a direct visual reading of the pressure inside the system, so the appliance can be checked and topped up correctly during servicing or fault finding. The gauge is a serviceable spare rather than a consumable, and is normally replaced when the dial becomes inaccurate, sticks, or the body begins to weep.

• The needle sits at zero or fails to move when system pressure changes.
• The reading is erratic, jumps, or disagrees with a known-good external gauge.
• The needle sticks partway round the dial and does not return smoothly.
• The dial face is clouded, discoloured, or the scale markings are no longer legible.
• Water or staining is visible around the gauge body or its connection to the appliance.

• Confirm the part number 101271 against the appliance documentation or the label on the existing gauge.
• Check the model and serial number on the appliance data badge to confirm the correct variant.
• Inspect the sealing washer or O-ring at the gauge connection and replace it if it is compressed or perished.
• Isolate and drain the appliance as required before removing the old gauge, and follow the manufacturer's service instructions.