Radiators only get warm at the bottom or some radiators stay cold while others heat up normally.

Safety first: Radiators and pipework can be hot; use caution when bleeding or adjusting valves.

• Bleed radiators: Use a radiator key to release trapped air from cold radiators, then re-pressurise the system if needed.
• Check TRVs and lockshields: Ensure thermostatic radiator valves are open and that lockshield valves are not fully closed.
• Engineer actions:
  • Assess for sludge and recommend a powerflush if necessary.
  • Clean or replace the primary heat exchanger if restricted.
  • Adjust pump speed or replace the pump if underperforming.
  • Balance the system by adjusting lockshield valves to ensure even heat distribution.