Rinnai Rinnai RL75iN RL Series Tankless Water Heater 10 Error Fix: Blocked Exhaust — Air Pressure Switch

Error code 10 on the Rinnai Rinnai RL75iN RL Series Tankless Water Heater means: Blocked Exhaust — Air Pressure Switch. The air pressure switch has detected abnormal pressure in the combustion chamber or exhaust system, indicating a blocked or restricted vent. Error code 10 is specifically triggered by the air pressure switch (also called the vent pressure sensor) and may indicate a more severe blockage than code 05. The unit will not operate until the condition is cleared. Check the entire vent run from the unit to the exterior termination. Look for disconnected vent joints that may be allowing exhaust gases to leak into the building. Verify the vent pipe diameter matches the installation requirements. On long vent runs, condensation can accumulate and partially block the pipe — ensure proper slope for condensate drainage. The air pressure switch itself can also fail. Test the switch by disconnecting the sensing hose and blowing gently into the port — the switch should click. If the switch is faulty, replace it.

The most successful fix is "Test and Replace Faulty Air Pressure Switch" (hard difficulty, ~60 minutes). Estimated DIY cost: $10-$20. 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 ("Test and Replace Faulty Air Pressure Switch") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Needle-nose pliers.

DIY cost: $10-$20. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

The Rinnai Rinnai RL75iN RL Series Tankless Water Heater has 8 other known error codes, including: 02 (Ignition Failure), 03 (Bath Fill Function Abnormality), 05 (Blocked Exhaust / Air Supply), 11 (No Ignition), 12 (Flame Failure), and 3 more.

Error code 10 also appears on 8 other Rinnai models: Rinnai RE180iN RE Series Non-Condensing Tankless Water Heater, Rinnai RL94iN RL Series Tankless Water Heater, Rinnai RSC160iN Condensing Combi Boiler, Rinnai RU130iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RU199iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RUR199iN Sensei Recirculating Tankless Water Heater, and 2 more. The fix may vary by model, so check each model's specific page for tailored repair steps.