Cast iron radiators are better than steel versions in some respects, but are disadvantageous in other comparative ways.
A big benefit of cast iron radiators is their construction – they are extremely well built and heavier and stronger than steel models.
Both cast iron and steel radiators provide a similar heat output and are equally as efficient, but they distribute their heat very differently.
It takes cast iron radiators much longer to heat up, so you need to plan ahead and switch them on early for when you want the room to be heated to a comfortable temperature later in the day.
On the flip side of this, they retain their heat very well indeed. So to save on energy costs, you can switch them off once they’ve reached an appropriate temperature and still enjoy their heat for hours to come.
Considering these properties, cast iron models are often utilised as kitchen or lounge radiators, rather than as a substitute for bathroom radiators, for instance.