Boiler runs but radiators upstairs are hot while downstairs remain cold (or vice versa)

Safety first: Radiators can be hot; use a cloth when handling bleed valves.

User checks:

• Bleed the cold radiators first to remove trapped air.
• Ensure their TRVs and lockshields are open.
• Partially close the lockshield valves on radiators that get very hot quickly to encourage flow to cooler radiators (balancing).

Professional actions:

• An engineer can check for zone valve faults, perform a system flush, and properly balance the system.