High-efficiency, gas-fired, heat-pipe, warm-air heating system

Four residential heat pipe furnaces were installed at selected test sites early in 1982. Each furnace unit operated at 100,000 Btu/hr heat input with a steady state efficiency of 86 percent. Two of the units were life cycle tested in laboratories; no major difficulties were encountered during their operation. Two additional furnaces were tested in homes. Field test performance confirmed that a steady state efficiency of 86 percent and a seasonal efficiency of 82-83 percent were obtained. A major furnace manufacturer has been licensed to manufacture and sell the heat pipe furnace developed by Thermo Electron under GRI sponsorship. A manufacturing prototype furnace was designed and fabricated taking into consideration the production capabilities of the manufacturer. The furnace is rated at 105,000 Btu/hr heat input and has a steady state efficiency of 85 percent. A field test was begun to continue through the 1982-83 heating season.