Boiler runs continuously and overheats rooms even when vSMART setpoint is reached or heating is turned off in the app.

Safety warning: Isolate mains power to the boiler before inspecting wiring. Overheating can damage the system.

Steps to diagnose:

• Check app status: Confirm that the app shows no heating demand and that setpoints are low.
• Power cycle: Turn off the boiler and vSMART interface for 1–2 minutes, then restore power and observe if the boiler still runs without demand.
• Inspect wiring (pro): A qualified engineer should verify that the boiler's call‑for‑heat terminals are correctly wired to the vSMART interface and that no permanent link is forcing demand.
• Test interface relay: If the interface uses a relay output, test whether the relay opens when there is no demand. A stuck relay requires replacement of the interface module.

Continuous running despite correct control signals usually indicates a boiler or interface hardware fault that must be addressed by a professional.