Boiler runs but radiators do not get hot or only partially heat up.

How to Fix / Troubleshooting

Safety: Radiators and pipework can be hot; use a cloth when bleeding valves.

User checks:

Bleed all radiators starting from the lowest floor to the highest, topping up system pressure as needed.
Ensure thermostatic radiator valves (TRVs) are set to an open position.
Check the boiler’s flow temperature setting is appropriate for your system (refer to EHC manual).

Engineer checks:

Check pump performance on the EHC boiler; verify it is running at the correct speed and not airlocked.
Balance the heating system by adjusting lockshield valves to ensure even heat distribution.
Power flush the system if sludge is present and fit a magnetic filter.

Improving circulation and balancing will usually restore full radiator performance.