Water leaking from the bottom of the Navien furnace cabinet

Safety: Turn off power and gas. Close system isolation valves if possible. Water may be hot; use caution.

• Identify leak source: Remove the front cover and use a flashlight to trace the leak. Check around the primary heat exchanger, pump connections, and internal piping.
• Inspect condensate system: Verify that the condensate trap and hoses are intact and not cracked or disconnected. Replace damaged components.
• Check pressure relief valve: If water is discharging from the relief valve outlet, check system pressure. A failed expansion tank or overfilled system can cause relief valve discharge. Replace the expansion tank or adjust system pressure as needed.
• Heat exchanger leak: If water is seeping from the heat exchanger body or welds, the exchanger is likely failed and must be replaced by a Navien-authorized technician.