The law of thermodynamics say there are three ways heat can be transferred.
1) Conduction- Heat travelling from an area of high temperature to an area of low temperature within an object.
2 Convection - Heat circulation in an atmosphere of water or gas
3 Radiation- Electromagnetic transfer even within a vacuum.
The majority of heating systems rely on convection. Far Infra red heaters produce solely radiant heat, using what is known as the Far Infrared part of the spectrum.The sun emits electromagnetic radiation across the whole of the spectrum shown on the chart below. Far Infrared heaters heat objects rather than air as is the case with most conventional heating