System reports 'OpenTherm Error' or modulating control failure (for Hive models supporting OpenTherm)

Safety first: OpenTherm connections are low-voltage but are inside mains-powered equipment. Isolate power before accessing terminals.

• Check compatibility: Confirm that your boiler supports OpenTherm and is configured for it in the boiler’s installer menu.
• Inspect wiring: With power off, check that the two OpenTherm wires are securely connected to the correct terminals on both the Hive receiver and boiler. Polarity usually does not matter, but loose connections will cause errors.
• Fallback to on/off: If OpenTherm errors persist, temporarily configure the system to use simple on/off control (if supported) to restore heating while you arrange professional help.
• When to call a pro: Persistent OpenTherm errors may indicate a faulty boiler control board or Hive receiver interface and should be diagnosed by a heating engineer.