Boiler runs but radiators remain cold or only lukewarm.

Safety: Radiators and pipes may be hot. Use gloves when bleeding.

• Bleed radiators: Starting from the highest floor, bleed each radiator until water flows without air. Recheck system pressure and top up if needed.
• Check pump operation: Ensure the pump is running and set to an appropriate speed. Listen for unusual noises indicating wear.
• Clean filters: Isolate and clean any dirt separators or magnetic filters on the return to the Klimosz boiler.
• Adjust heating curve: If using weather compensation, increase the heating curve or target flow temperature in the Klimosz controller menu.