E10 on display, unit will not fire; pressure gauge may read low or zero.

Warning: Hot water under pressure can cause burns. Allow system to cool before opening any valves or vents.

• 1. Read system pressure: Check the hydronic pressure gauge on the Triangle Tube unit. Most systems require around 12–20 psi when cold (check your manual).
• 2. Open fill valve: Ensure the automatic fill valve or manual feed valve to the system is open. Slowly add water until the gauge reaches the recommended pressure.
• 3. Bleed air: Air in the system can cause false low pressure readings. Bleed air from radiators, air vents, and the air separator. Top up pressure again if it drops.
• 4. Inspect for leaks: Look around the boiler, relief valve discharge, and visible piping for signs of water leakage. Repair leaks before repeatedly refilling.
• 5. Check pressure sensor wiring: Locate the electronic pressure sensor on the boiler manifold. Inspect its connector and wiring for damage. Reseat the plug.
• 6. Sensor test/replacement: If the mechanical gauge shows normal pressure but the control still reports E10, the pressure sensor may be faulty and should be replaced with an OEM part by a qualified technician.