Both cast iron radiators and steel radiators have their advantages and disadvantages. Cast iron is much heavier than steel, making it less practical to move around. However, this material does mean that cast iron radiators are extremely durable and strong. A cast iron radiator does take longer to heat up than a steel radiator, however, this also means cast iron radiators retain their heat for much longer. This makes cast iron radiators a great choice for reducing energy wastage and heating bills, but maintaining warmth.