Vaillant Condensate / Flue Joint Leak

Boiler flue dripping water externally or staining wall

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Incorrect flue slope, Failed flue seals, Condensate running back to terminal, Cracked flue elbow or joint

Safety: Flue integrity is critical for safe operation. Do not attempt to dismantle the flue yourself.

Observe drip source: Check whether water is coming from the flue terminal itself or from a joint.
Check for staining: Look for white streaks or corrosion around the flue, indicating condensate leakage.
Call an engineer: A Gas Safe engineer must inspect and, if necessary, reassemble or replace flue components and ensure correct fall back to the boiler.

Hard 4/5

Flue Kit / Flue Seals

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