Building with the Sun: Solar Energy and Radiant Floors

by Alex Wilson Solar energy is well suited to radiant-floor heating because the temperature requirements for the slab are low (80 to 125 F), and solar collectors are much more efficient when operated at relatively low temperatures. But the nature of solar heat adds a number of complexities when it comes to controls and back-up requirements for radiant floors. The Basic System Solar energy can be used a number of ways in radiant floors. The easiest approach is simply to pump solar-collection fluid directly through the tubing in the slab, without using any intermediate storage. The beauty of this approach is its simplicity, but how do you control the slab temperature? To avoid large fluctuations, the system