Flow and balancing
Valve position, balancing and circulation can affect how heat is distributed through a radiator and around the system.
Radiator symptom guide
Why is my radiator cold at the bottom?
A cooler lower section may be associated with restricted flow or deposits, but the temperature pattern is a symptom rather than a diagnosis.
Possible areas to investigate
Deposits or debris
Material within a radiator may restrict circulation, but the symptom does not show how much is present or what treatment is appropriate.
Controls or faults
Pump performance, controls, valve faults and other system issues can produce similar or overlapping symptoms.
Use evidence before treatment
Do not assume that one cold radiator means the whole system needs cleaning. If there is leakage, unsafe temperature, electrical concern or a suspected gas issue, stop and contact the appropriate emergency service or qualified professional.