F5 displayed and thermostat cannot control domestic hot water (DHW) functions on compatible Protherm boilers.

Safety: Boiler settings should be adjusted only with power isolated if covers are removed. Follow boiler manual and local regulations.

• Step 1 – Check thermostat mode:
  • Open the thermostat settings menu.
  • Ensure that DHW control or Hot water is enabled if your system uses the thermostat for DHW.
• Step 2 – Verify boiler parameters:
  • Access the Protherm boiler installer menu (refer to boiler manual).
  • Confirm that the boiler is set to accept DHW control via eBUS/OpenTherm.
  • Enable DHW control if disabled.
• Step 3 – Check DHW sensor on boiler:
  • If the boiler itself shows a DHW sensor error, resolve that first (sensor replacement on boiler side).
  • A faulty DHW sensor can prevent proper communication with the thermostat.
• Step 4 – Confirm compatibility:
  • Verify that your Protherm smart thermostat model is compatible with your specific Protherm boiler model for DHW control.
  • If not compatible, disable DHW control on the thermostat and use boiler’s own DHW settings.
• Step 5 – Reset both devices:
  • Power cycle the boiler and thermostat.
  • Recheck for F5. If it persists, a firmware or communication module fault may require professional service.