Water heater is leaking water from the bottom of the casing

Safety: Turn off power and close water and gas valves. Water inside the unit can damage electronics and create shock risk.

• Identify leak source: Remove the front cover and use a flashlight to trace water back to its origin. Check around the plate heat exchanger, pump, air vent, and relief valve.
• Check relief valve: If water is discharging from the relief valve outlet, system pressure may be too high or the valve may be faulty. Verify pressure and replace the valve if it drips at normal pressure.
• Inspect hydraulic block: Look for cracks or weeping joints on the plastic or brass hydraulic group. Tighten unions gently; do not overtighten plastic parts.
• Replace faulty components: Replace leaking plate heat exchanger gaskets, air vents, or hydraulic blocks with genuine Viessmann parts.
• Dry electronics: If water has contacted the PCB, allow it to dry completely and inspect for damage. Severe contamination may require board replacement.