Display shows code 5, boiler shuts down on high temperature

Safety first: Overheat conditions can damage the boiler and pipework. Turn off power and allow the appliance to cool fully before working on it.

Initial checks:

• Bleed air: Bleed radiators and any automatic air vents near the boiler to remove trapped air that can cause local overheating.
• Check system pressure: For sealed systems, verify that the pressure gauge on the Intergas boiler is within the recommended range (typically 1.0–1.5 bar when cold). Top up via the filling loop if low, and then bleed again.
• Verify pump operation: When there is a call for heat, listen and feel for the circulation pump running. If it is silent or excessively hot to touch, it may be seized.

Technician steps:

• Inspect pump: Check electrical supply to the pump. Free a stuck rotor if possible or replace the pump cartridge/assembly.
• Check overheat thermostat: Test continuity of the manual reset or automatic overheat thermostat on the flow pipe or heat exchanger. Replace if faulty.
• Examine primary heat exchanger: Look for signs of sludge or scale blockage in the Intergas dual heat exchanger. Power-flush the system and chemically clean if necessary.

After correcting the cause, reset the overheat device (if manual) and restart the boiler. If code 5 recurs, stop using the appliance and call a professional.