Navien furnace produces gurgling or trickling water sounds inside the unit

Safety: Turn off power before bleeding air. Water may be hot.

• Check system pressure: Ensure the hydronic system pressure is within the recommended range. Add water if needed.
• Bleed air: Use the automatic air vent on top of the Navien unit (if equipped) and manual bleeders on the system to purge air until gurgling subsides.
• Inspect condensate trap: Remove and clean the condensate trap to ensure free flow. A partially blocked trap can cause water to back up and make noise.
• Refill procedure: If the system was recently drained, follow Navien's recommended fill and purge procedure to ensure all air is removed from the primary and secondary loops.