Abstract: A hydronic heating system for radiantly heating habitable space is disclosed. The radiant heating system uses heated fluid circulated through under-floor or in-wall endless pipe loops and heat radiation fins which clip onto the pipe loops. The system permits heated fluid to be circulated at boiler temperatures, obviating a requirement for mixing valves, heat exchangers or buffer tanks, because the endless pipe loop is spaced away from the wall or floor and all heat is exchanged through convection by air surrounding the heat radiation fins. The advantages include a more affordable heating system due to less pipe, fewer components and faster installation. As well, the system provides a more even heat distribution and the eliminates hot spots. Furthermore, the endless pipe loops are spaced from the floor or wall surface, and thereby protected from danger of puncture by a nail or screw driven through the surface.