Condensate water backs up or drips from the furnace casing

Safety first: Condensate is mildly acidic; wear gloves and eye protection.

• Locate the condensate trap and remove it according to the ATAG manual.
• Rinse the trap thoroughly with clean water to remove sludge.
• Check the condensate pipe for kinks, sags, or external freezing; thaw gently if frozen.
• Ensure the pipe has a continuous fall to the drain to prevent standing water.
• Refit the trap, refill with clean water, and test operation.