F30 displayed, furnace may run in backup mode or shut down

Safety first: Turn off power before accessing controls.

• Step 1 – Check control location: Ensure the Protherm room controller is not exposed to drafts, direct sunlight, or heat sources.
• Step 2 – Inspect wiring: For remote sensors, check the cable for damage and correct polarity.
• Step 3 – Replace sensor/control: If readings are clearly wrong (e.g., showing 0°C or 99°C indoors), replace the sensor or the entire room controller with a compatible Protherm unit.