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Rinnai Error Code 11 - Ignition Failure (No Flame Detected)

Medium Severity

The tankless water heater attempts ignition, but the flame rod sensor does not detect a stable burner flame within the required ignition window.

Appliance: Rinnai Water Heaters & Boilers

Estimated Time: 20 minutes

Tools Required: Phillips screwdriver, fine steel wool

⚠ Common Symptoms & Observations

No hot water from faucets; heater clicks several times trying to fire up; controller beeps and flashes Code 11.

🔍 Root Causes for Code 11

Gas shutoff valve closed or gas bottle empty
air in the gas line after line maintenance
dirty flame rod sensor coated in carbon
blocked exhaust vent piping
low gas supply pressure.

🔧 Step-by-Step DIY Troubleshooting & Fix Guide

Verify the gas isolation valve right below the water heater is aligned parallel with the pipe (fully open).

Check other gas appliances (like kitchen stove) to confirm home gas supply is active.

Inspect the PVC/polypropylene exhaust vent on the exterior wall to ensure leaves, bird nests, or snow are not blocking air exhaust.

Clean the flame sensor: Remove the front cover panel (4 screws), locate the flame rod with ceramic insulation, and gently rub the metal rod with fine steel wool to remove carbon soot.

🔄 Master Reset Procedure for Rinnai

Press the Power button on the remote temperature controller OFF and ON twice to clear Code 11.

Technician Tip: If the error code reappears immediately after a hard reset, the control board has detected an active electrical open circuit or failed component that requires physical inspection.