Display shows E06 and the furnace stops; may occur during operation or startup.

Safety: Turn off power and allow the furnace to cool before touching any hot pipes or components.

• Check system pressure and circulation: Verify the heating system pressure on the gauge (if present) is within the range specified by Kospel. Low pressure can cause poor flow and overheating. Top up the system via the filling loop if allowed by local regulations.
• Bleed air from radiators: Air locks can stop circulation. Use a radiator key to bleed air from the highest radiators until water flows steadily.
• Inspect circulation pump: Locate the built-in circulation pump. With power on and a heat demand, touch the pump housing carefully; it should vibrate slightly and get warm. If it is silent and cold, it may be seized or not powered.
• Reset high-limit thermostat: Some Kospel furnaces have a manual reset high-limit on the heat exchanger. After cooling, press the reset button if accessible (refer to the user manual).

If E06 recurs, the pump, high-limit thermostat, or control board may need replacement. Contact a Kospel service technician to avoid damage to the heat exchanger.