Radiators not heating properly while boiler appears to run normally

Safety: Allow radiators to cool slightly before bleeding to avoid scalds.

• Bleed radiators: Starting from the top floor, bleed each radiator until water flows steadily. Re-pressurise the system as needed.
• Check TRVs: Ensure thermostatic radiator valves are open and not stuck. Gently free stuck pins.
• Balance system: Partially close lockshield valves on radiators that heat quickly to push more flow to colder radiators.
• Technician tasks: If circulation remains poor, a heating engineer should check the circulation pump and consider system flushing.