Boilers are used with systems typically called hot water heat, steam heat or radiant heat. These units burn natural gas or propane and heat water or steam in a sealed water-circulating system. They then transfer that heat through your home via strategically placed radiators or through tubing in your floors. Boilers are very efficient with ratings as high as 98%. Radiant heat also provides consistent comfortable heat with greater zoning capabilities than traditional forced air systems. And boiler can even heat your domestic water.