E11 displayed, unit may shut down unexpectedly; pressure reading may be abnormally high.

Warning: High pressure can cause the relief valve to discharge hot water. Use caution and allow the system to cool.

• 1. Check pressure gauge: If the gauge reads above the normal operating range (often >30 psi), do not continue to run the heater.
• 2. Inspect expansion tank: Locate the expansion tank connected to the Triangle Tube system. Tap it lightly; it should sound hollow on the air side and solid on the water side. If it feels completely full of water, the bladder may have failed.
• 3. Verify air charge (if equipped and system is cool): Isolate and drain the expansion tank, then check the air charge with a tire gauge. Recharge to the manufacturer’s specified pressure (often 12 psi) using an air pump.
• 4. Reduce system pressure: With the system cool, carefully drain water from a drain valve until the pressure gauge returns to the recommended range.
• 5. Check fill valve: Ensure the automatic fill valve is not overfeeding. If pressure rises over time without heating, the fill valve may be leaking and should be replaced.
• 6. Professional service: If the expansion tank is waterlogged or the relief valve is discharging frequently, have a qualified technician replace the tank and verify system sizing.