Water dripping from the flue or condensate pipe connection

Safety: Turn off power. Condensate is mildly acidic; wear gloves and eye protection.

• Check condensate joints: Inspect the trap and hoses for loose clamps or cracks. Tighten or replace as needed.
• Verify flue slope: Ensure the flue is installed with the correct fall back to the boiler or to the drain, as specified by Viessmann.
• Inspect flue joints: Look for water staining around flue connections. Replace any damaged seals and reassemble according to the installation manual.
• Test drain: Pour a small amount of water into the condensate trap and confirm it drains freely without leaks.