Navien
Zone Flow Imbalance / Airbound Zones
Navien furnace runs but some zones or radiators stay cold
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Air trapped in specific zones, Stuck zone valve, Closed balancing valve, Undersized or miswired zone circulator
How to Fix / Troubleshooting
Safety: Turn off power before working on zone valves or pumps. Water may be hot.
- Bleed affected zones: Use manual bleeders on cold radiators or manifolds to purge air until a steady stream of water flows.
- Check zone valves: Verify that motorized zone valves open when the thermostat calls for heat. Manually open the valve (if possible) to test flow. Replace the actuator or valve if it does not open.
- Inspect balancing valves: Ensure that balancing valves on manifolds or branches are open enough to allow flow to cold zones.
- Verify zone pump operation: If separate pumps are used for zones, confirm that the pump for the cold zone runs when called. Replace failed pumps.
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Repair Difficulty
Medium
3/5
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