Heating guide
The position of a cold area can help describe the symptom, but it does not confirm the cause. These checks help you gather useful information without opening or altering the heating system.
What the pattern may indicate
Let the heating run normally, then compare radiators carefully without touching pipework or surfaces that feel excessively hot.
A cooler area at the top can be consistent with trapped air. Radiator bleeding may be appropriate, but follow the heating-system or manufacturer instructions and stop if you are unsure, there is a leak, or the system pressure needs attention.
A cold lower section can be linked to restricted flow or deposits inside the radiator or heating system. Do not drain, flush or open the system yourself; diagnosis and system work should be handled by a heating engineer.
If other radiators heat normally, the issue may be local to that radiator, its valves, trapped air or system balancing. Check that an adjustable valve has not simply been turned off, but do not force or dismantle a stiff valve.
Safe homeowner checks
Do not remove boiler panels, dismantle valves, drain the heating system or use chemical treatments without competent advice. If several radiators are affected, the problem returns, or the system needs opening, contact a heating engineer.
Nebula can discuss cold radiators, valves and wider circulation symptoms. Send a clear photo and explain which parts of the radiator remain cold.
