It is important when buying a new radiator to consider the heat output you will need for each room. This is generally measured in BTU’s (British Thermal Units).
To calculate the BTU level required, all you need to do is find the cubic footage measurement per room (Length X Width X Height = Cubic Volume). If the room is on the ground floor, then times the answer by 5 but if the room is on the first floor times the answer by 4.
All the radiators listed on the website show the BTU output per section so it is easy to find the right size for you.