Here's how it works. Uponor radiant floor heating systems circulate warm water through PEX tubing embedded in the floor of your home. The heat radiates up through the floor, warming the people, furnishings and air in the room. The warmth stays down around where the people are, not up at the ceiling or lost to the outdoors every time a door or window is opened. It's a comfortable, even heat where cold spots and drafts are eliminated.