A radiant floor heating system combines a series of water coils alternating beneith a slab of given material (concrete) in order to heat the slab, providing a radiant source of heat. The "Hydrojet" distribution unit [see below] first heats up a given volume of water, then releases/recycles the water by implement of pressure throughout the under-slab coils.

water heater [left] shares a common Hot water with the distribution tank [right]

This system in particular uses a series of "flex"-tubing for the coils (verses a more standard "T-pipe" method) as well as an energy efficient distribution/heating unit.