A fireplace jacket assembly and heating system associated therewith. A fireplace jacket assembly including water chambers on five sides of an open wood-burning fireplace having means for providing water communication and circulation therebetween is placed in a conventional heating or hot water system. A pump circulates the water between the component parts of the system including a water storage tank and a radiator, and means are provided responsive to the temperature of water within the storage tank for preventing heating thereof by conventional (i.e., fossil fuel or electricity) means, or by a solar heating system. An opening formed in the bottom of the fireplace jacket provides for greater efficiency.