Boiler/furnace does not start, display shows code 0, no ignition attempt heard

Safety first: Turn off electrical power to the Intergas furnace at the service switch and isolate the gas supply before removing any covers. Only remove the sealed combustion cover if you are qualified and local regulations allow.

Step-by-step checks:

• Verify thermostat demand: Set the room thermostat or controller to a higher temperature than room temperature and ensure it is in HEAT mode. Check that any programmer or timer is calling for heat.
• Check control wiring: Inspect the low-voltage thermostat wires at the boiler terminals (e.g. room thermostat contacts on the Intergas PCB). Look for loose connections, broken conductors, or corrosion. Tighten terminals gently.
• Check external controls: If there is an external relay, zone valve, or wiring center, confirm it is energizing and sending a call-for-heat signal to the boiler.
• Reset the boiler: Restore power and press the reset button (if fitted) or power-cycle the unit for 30 seconds. Observe if the code changes from 0 to a normal operating status.
• Inspect fuses: With power off, check any accessible low-voltage fuses on the Intergas PCB for continuity. Replace only with identical rating if blown.

When to call a professional: If there is confirmed thermostat demand but the boiler remains on code 0 with no ignition sequence, the PCB or internal control circuitry may be faulty. This requires a certified gas technician familiar with Intergas controls.