They work on exactly the same principle as modern radiators. The only difference is that cast iron radiators usually have a larger internal volume, so they take a few more minutes to warm up. This also means that they stay warm well after the boiler has been turned off.
While a cast iron radiator takes longer to heat up than a flat panel radiator, it also takes longer to cool down. The efficiencies of both types of radiator are approximately equivalent.
The best efficiency savings are not to be made through the type of radiator, rather through a highly efficient boiler, thermostatic radiator valves, clever use of insulation and by turning off radiators in rooms that are not used.
Water has a high specific heat capacity, and that is one of the reasons why island nations such as Britain enjoy milder winters than continental countries – oceans are better at holding heat than land.
All the energy spent heating the cast iron radiator in the first place is now dissipated slowly as the radiator cools down; no energy is destroyed, it’s just dissipated slowly with a radiator that continues to heat the room well after the boiler has been turned off.
By localising temperature control to the environment of each radiator, thermostatic radiator valves help to eliminate wasteful heating and can help regulate the temperature throughout a house by allowing cool rooms to heat for longer than a well-insulated room or one where there are other heat sources contributing to the ambient temperature other than the radiator.
So in conclusion, the best efficiency savings are not to be made through the type of radiator, rather through a highly efficient boiler, thermostatic radiator valves, clever use of insulation and by turning off radiators in rooms that are not used.
Take a look at these beautiful stainless steel radiators. A great collection which includes vertical radiators, designer radiators and towel rails all manufactured from high quality stainless steel and available in both polished and brushed finishes.