HITZER’S ENERGY MASTER II Model 710 stoker hot air furnace is one of the most efficient and technologically advanced stoker furnaces on the market today. Its 160 pound stainless steel hopper and large ash pan provide long unattended burn times. The ENERGY MASTER has the ability to be operated with a power vent as well as a chimney. This makes it usable where there’s no chimney and no way to install one.