Wall heating systems work very similar to underfloor heating in that they heat a room predominantly by radiation (like the sun) as a result of pumping warm water through looped pipes.
Wall heating systems are often used as an alternative to UFH in renovation projects. Until the recent additions of retrofit and wall heating systems, installing ufh resulted in the floor having to be excavated. Although Retrofit UFH kits have eliminated the need to fully excavate flooring, this does not mean wall heating systems are now redundant. It is not always economically viable to re-lay flooring after installing ufh such as in renovations of older homes.