Display shows E11; unit may heat but then shut down unexpectedly.

Shock hazard: Turn OFF power at the breaker and verify with a tester. Do not operate the unit until the ground fault is resolved.

Troubleshooting steps:

• Remove the front cover and inspect for any signs of water leaks, condensation, or corrosion inside the heater. Repair any plumbing leaks and dry the interior thoroughly.
• Check the equipment ground connection at the terminal block and ensure it is tight and connected to a proper grounding conductor.
• Disconnect each heating element and test insulation resistance between each terminal and ground using a megohmmeter if available. Low insulation resistance indicates a failing element.
• Replace any heating element that shows leakage to ground or visible damage.
• If no moisture or element faults are found, the control board's ground fault detection may be defective and require replacement.
• After repairs, reassemble, restore power, and test operation. Monitor for recurrence of E11.

If you are not equipped to test insulation resistance, contact a licensed technician.