Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater 10 Error Fix: Abnormal Combustion — Blocked Vent

Error code 10 on the Rheem Rheem RTGH-95DVLN Prestige 9.5 GPM Condensing Tankless Gas Water Heater means: Abnormal Combustion — Blocked Vent. The unit has detected incomplete combustion or unsafe exhaust gas conditions. This code indicates the air-to-fuel ratio is outside of acceptable parameters. Causes include: insufficient combustion air supply from a blocked intake vent, partially blocked exhaust vent, improper vent sizing or length exceeding the maximum specification in the installation manual, or operating at high altitude without proper deration adjustments. Check both the intake and exhaust vent terminations on the exterior of the building for obstructions such as ice, leaves, bird nests, or wasp nests. Verify the vent pipe diameter and total equivalent length match the installation manual specifications.

The most successful fix is "Inspect and Replace Vent Piping to Manufacturer Specifications" (hard difficulty, ~120 minutes). Estimated DIY cost: $50-$100. HomeMD has 2 community-ranked fixes for this error.

This error is rated critical 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 Vent Piping to Manufacturer Specifications") is rated hard difficulty and takes about 120 minutes. Tools needed: Pipe wrench, PVC pipe cutter, Screwdriver set, Combustion analyzer (optional).

DIY cost: $50-$100. Professional repair typically costs $300-$500. 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), 11 (Ignition Failure — No Flame Detected), 12 (Flame Failure — Flame Lost During Operation), 14 (Thermal Fuse Activated — Overheat Safety), 16 (Overheating — Outgoing Water Too Hot), and 3 more.