Furnace shows E20; condensate pump may be running or unit may shut down during wet conditions.

Safety: Turn off power before working on condensate components. Water may be present; protect surrounding areas.

• Inspect trap and drain: Locate the condensate trap on the Wolf condensing furnace. Remove and flush it with clean water to remove debris or slime. Ensure the drain line slopes continuously to the drain and is not kinked.
• Check pump (if installed): If a condensate pump is used, verify it is plugged in and operating. Pour water into the pump reservoir and confirm it activates and discharges water. Replace the pump if it fails to run or pump out.
• Overflow switch: Many systems include a float switch that opens on high water. Inspect and clean the float. Ensure wiring to the Wolf control board is intact.
• Reset and test: After clearing blockages and verifying pump operation, restore power and call for heat. If E20 persists, the condensate switch or related wiring may need replacement.