Rheem Error Code 10: Rheem Code 10 - Air Supply or Exhaust Blockage
Warning: Your Rheem tankless water heater has detected a blocked air intake or exhaust vent. The unit will not operate until airflow is restored.
How to Fix Rheem Code 10
- Step 1: Go outside and visually inspect the exhaust vent terminal. Remove any visible debris, bird nests, leaves, or ice buildup.
- Step 2: Check that nothing is placed against or blocking the air intake on the unit.
- Step 3: If you have a condensate drain line, make sure it is not frozen or kinked.
- Step 4: Power-cycle the unit by turning it off, waiting 30 seconds, and turning it back on.
- Step 5: If the error returns after clearing the vent, call a licensed technician to inspect the full vent run.
How to Reset Rheem Code 10
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Rheem Error Code 10 Mean?
Indicates blocked air intake or exhaust venting. The unit detects insufficient combustion air supply or restricted exhaust gas flow.
Common Causes
- Blocked or obstructed exhaust vent terminal — bird nests, debris, ice/snow buildup
- Crushed or kinked vent pipe preventing proper exhaust flow
- Intake air filter clogged with dust or lint
- Vent pipe exceeds maximum length or has too many elbows for the model
- Condensation buildup or frozen condensate drain line blocking exhaust
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Error appears during cold weather | Inspect exhaust terminal for ice buildup or frozen condensate | Clear terminal with no ice obstruction |
| Error appears intermittently | Measure vent pipe total equivalent length vs. model specs | Within max vent length per installation manual |
| Error persists after clearing vents | Test combustion fan motor RPM and amp draw | Fan runs at rated RPM with amp draw within nameplate specs |
| Fan operates normally | Inspect heat exchanger for soot buildup restricting exhaust flow | Clean heat exchanger fins with no carbon deposits |
Applicable Rheem Models
- NCB(gas)
- NPE(electric)
- R801T(gas)
- R92E(electric)
- R92V(gas)
- RGE(gas)
- RH2T(electric)
- RNC(dual_fuel)
- RNE(electric)
- RNG(gas)
- RP16(electric)
- RPB(gas)
- RTGH(gas)
- Rheem Classic(gas)
- Rheem Classic 80 Plus(gas)
- Rheem Classic 80% Gas Furnace(gas)
- Rheem Classic 90 Plus(gas)
- Rheem Classic Plus Series(gas)
- Rheem Classic Series(dual_fuel)
- Rheem Prestige(gas)
- Rheem Prestige 95% Gas Furnace(gas)
- Rheem Prestige Series(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Combustion Fan Motor | SP20875 | — | Find Part |
| Air Intake Filter | SP20127 | — | Find Part |
| Exhaust Vent Terminal | — | — | — |
Related Codes on Same Models
Other codes that affect the same Rheem model families as 10.
| Code | Description | Severity |
|---|---|---|
| A001 | Ignition Failure | Warning |
| A003 | Abnormal Ignition | Warning |
| A004 | False Flame Detection | Warning |
| A008 | Exhaust Temperature High | Warning |
| A011 | No Flame Detected | Warning |
| A021 | Over-Temperature | Warning |
| A031 | Inlet Thermistor Open/Short | Warning |
| A041 | Outlet Thermistor Open/Short | Warning |
| A043 | Water Level Error | Warning |
| A051 | Fan Motor Abnormality | Warning |