A tankless water heater stuck in lockout mode can halt hot water service in an entire building. If your Rheem RTG-950-VLN displays the E1-13 error code even after replacing a faulty gas regulator, the unit may be holding a persistent fault. Simply unplugging and replugging often fails to clear the error because the control board remains locked. This guide shows you exactly how to reset a tankless water heater after an E1-13 error using a structured, field-tested approach. You will learn how to isolate auxiliary equipment, perform a hard power reset, verify gas conditions, and recognize when professional service is required.
Disconnect the Recirculating Pump First
Auxiliary components can interfere with the reset process, even when they function normally.
Isolate the Pump from the Circuit
The recirculating pump creates flow demand signals that can confuse the control board during startup. Leaving it connected may prevent successful ignition after a fault clear.
– Shut off power to the water heater at the breaker.
– Locate the pump wiring and disconnect it from the system.
– Keep the pump offline throughout the entire reset attempt.
Allow the System to Settle
Rushing the restart reduces your chances of success.
– Wait at least 5 minutes after disconnecting the pump.
– Ensure no hot water taps are open anywhere in the building.
– Reconnect only the water heater until normal operation resumes.
⚠️ Pro Tip: Test during low-demand periods. The fewer flow signals the unit sees, the higher the likelihood of a clean restart.
Perform a Full Power Reset
A hard power cycle clears stored fault memory that soft resets cannot reach.
Cut Power at the Breaker
Pressing the power button alone rarely clears a persistent E1-13 code.
– Locate the dedicated breaker for the water heater.
– Flip it to the OFF position to fully de-energize the unit.
Wait for Capacitors to Discharge
Skipping this wait time is a common mistake.
– Leave the breaker off for at least 5 minutes.
– Use this window to verify that gas and water valves are fully open.
Restore Power and Observe
- Flip the breaker back to ON.
- Press the power button on the unit.
- Watch the display for normal initialization and ignition attempt.
✅ Expected Result: Display initializes, the unit runs a self-check, and the burner lights if all conditions are correct.
❌ If E1-13 Returns: Move on to gas pressure verification.
Verify Gas Pressure with a Manometer
Even a newly installed regulator can deliver inconsistent pressure, which is the leading cause of recurring E1-13 faults.
Measure Inlet Pressure Accurately
Visual inspection is not enough for modern Rheem valves.
– Connect a U-tube or digital manometer to the gas pressure test port.
– Confirm the reading falls within Rheem specifications.
– Natural Gas: 3.5 to 7 inches water column (inWC)
– LP Gas: 8 to 11 inWC
Watch for Pressure Drops During Ignition
A momentary dip below the minimum threshold will trigger flame failure.
– Monitor pressure while the unit attempts to ignite.
– Any fluctuation during startup indicates a regulator or supply issue.
🛠️ Expert Note: Some new regulators require fine-tuning. If readings fluctuate, a licensed technician with calibrated tools should verify the supply.
Inspect the Flame Sensor and Ignition Electrodes
Dirty or worn ignition components are a frequent culprit behind phantom flame failures.
Clean the Flame Sensor
The sensor tells the control board whether a flame is actually present. A dirty sensor falsely reports “no flame” and locks the unit out.
– Turn off gas and power before opening the unit.
– Remove the sensor, usually secured by a single screw.
– Wipe gently with a lint-free cloth.
– Do not sand or scratch the surface.
Check Electrode Condition and Alignment
Weak or misdirected sparks prevent proper ignition.
– Look for carbon buildup, cracks, or erosion on the electrode tip.
– Confirm the gap is typically 3 to 5 mm from the burner surface.
– Adjust carefully without bending aggressively.
❌ Caution: Electrodes are fragile. Excessive force can cause cracking or internal shorts.
Confirm Venting and Airflow
Restricted combustion air or blocked exhaust forces the unit into safety lockout.
Inspect Intake and Exhaust Pipes
Blockages from debris, nests, or ice can starve the burner of air.
– Visually check both terminations outside the building.
– Clear any snow, leaves, or insect nests.
– Confirm venting material matches Rheem specifications, usually PVC or stainless steel.
Test Airflow at the Intake
A simple tissue test reveals suction problems.
– Hold a lightweight tissue near the intake port.
– It should be gently and steadily pulled inward.
– Listen for whistling or sucking sounds that indicate restriction.
✅ Quick Check: Weak or absent suction points to a venting problem that must be resolved before any reset will hold.
Address Persistent E1-13 Errors
If the code returns after all checks, deeper control issues may be at play.
Force a Double Reset
Some units enter a permanent lockout after repeated failures.
– Perform two consecutive power cycles.
– Turn off for 5 minutes, turn on, then turn off again for 5 minutes, and restore power.
– This sequence can force-clear stubborn fault memory.
Evaluate the Control Board
When every other variable checks out, the board itself may be the problem.
– Firmware glitches or moisture damage can prevent normal recovery.
– Only a qualified technician should replace or reprogram the control board.
📅 Field Note: In the original repair case, the technician planned to return with a manometer and spare parts, which is the right approach for stubborn E1-13 codes.
Prevent Future Lockouts
Proactive maintenance reduces the risk of repeat failures.
Schedule Annual Professional Inspections
- Clean the heat exchanger, flame sensor, and electrodes yearly.
- Verify gas pressure stability and vent integrity.
- Update firmware when Rheem releases revisions.
Monitor Startup Behavior
- Count how many ignition attempts occur before success.
- Frequent retries signal aging components that need attention.
Keep the Recirculating Pump Isolated During Repairs
- Always disconnect auxiliary pumps when troubleshooting ignition faults.
- Reconnect only after the unit has resumed normal operation.
Frequently Asked Questions About Resetting a Tankless Water Heater
Why does my tankless water heater still show E1-13 after a power reset?
The control board may be holding a persistent fault in memory. A single power cycle often fails to clear it. Try two consecutive resets, and verify gas pressure with a manometer before attempting again.
How long should I wait before restoring power to the water heater?
Wait at least 5 minutes after turning off the breaker. This allows capacitors to fully discharge and clears temporary fault memory from the control board.
Can a recirculating pump prevent a successful reset?
Yes. The pump can generate flow signals that interfere with ignition during startup. Disconnect it before attempting any reset, and leave it offline until the heater operates normally.
What gas pressure does a Rheem tankless water heater require?
Rheem units typically require 3.5 to 7 inWC for natural gas and 8 to 11 inWC for LP gas. Readings outside this range, or drops during ignition, will trigger E1-13.
When should I call a technician for an E1-13 error?
Call a licensed technician if the code returns after verifying gas pressure, cleaning the flame sensor, checking venting, and performing two full power resets. The control board may need professional diagnosis or replacement.
Key Takeaways for Resetting a Tankless Water Heater After E1-13
Learning how to reset a tankless water heater after an E1-13 error requires more than flipping a breaker. The most reliable approach combines isolating the recirculating pump, performing a full 5-minute power reset, and verifying gas pressure with a manometer. Cleaning the flame sensor and confirming clear venting address the remaining common causes. If the code persists after these steps, the control board likely needs professional attention. Start with the pump isolation and power reset tonight, then verify gas pressure at the next service window to restore reliable hot water in your commercial setting.
