Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater 11 Error Fix: Ignition Failure — No Flame Detected

Error code 11 on the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater means: Ignition Failure — No Flame Detected. The unit attempted to ignite the burner but no flame was detected after the ignition trial period. This is the most common tankless water heater error code. Causes include: gas supply shutoff valve closed, insufficient gas supply pressure (check with a manometer — natural gas should be 5-7 inches water column at the unit), air in the gas line (common on new installations — may need multiple ignition attempts to purge), a failed or weak spark igniter, incorrect igniter electrode gap, dirty or corroded igniter electrodes, a failed gas solenoid valve, or the wrong gas type installed (LP vs natural gas — the unit must be converted with the proper LP kit). Verify the gas supply first, then inspect the igniter assembly.

The most successful fix is "Inspect and Replace Igniter Electrode Assembly" (hard difficulty, ~60 minutes). Estimated DIY cost: $15-$25. HomeMD has 2 community-ranked fixes for this error.

This error is rated warning severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Inspect and Replace Igniter Electrode Assembly") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Feeler gauge, Multimeter, Fine sandpaper.

DIY cost: $15-$25. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

The Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater has 8 other known error codes, including: 05 (False Flame Detection), 10 (Abnormal Combustion — Blocked Vent), 12 (Flame Failure — Flame Lost During Operation), 14 (Thermal Fuse Activated — Overheat Safety), 16 (Overheating — Outgoing Water Too Hot), and 3 more.