Code 10
Rinnai Air Supply or Exhaust Blockage / Improper Venting

Water heater displays Code 10 and will not operate; often after installation or vent changes

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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

Incorrect vent length or diameter, Blocked intake or exhaust terminal, Too many elbows or improper vent configuration, Shared venting with other appliances

How to Fix / Troubleshooting

Safety first: Turn OFF gas and power. Venting issues can cause carbon monoxide hazards; do not operate the unit until resolved.

Steps to check:

  • Inspect vent terminations: Ensure both intake and exhaust terminations are clear of obstructions and meet Rinnai clearance requirements from walls, windows, and other openings.
  • Check vent materials: Confirm that only approved vent pipe (e.g., Category III stainless or manufacturer-specified concentric vent) is used. Replace any improvised or incompatible materials.
  • Review vent length and elbows: Compare the installed vent length and number of elbows to the Rinnai installation manual limits. Excessive length or elbows can trigger Code 10.
  • Check for shared venting: Rinnai tankless units must not share vents with other appliances. If they do, a professional must correct the installation.

When to call a professional: If you cannot verify vent design or if modifications are needed, contact a licensed Rinnai installer to redesign and certify the vent system.

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Repair Difficulty

Professional Required 5/5

Required Part

Vent Pipe Assembly
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