Study of Local West Sumatera Stove performances to boil gambir in Pesisir Selatan district showed the results that heat transfer efficiency is 11.6 %, very simple in operation but short service life, indoor pollution due to smoke and burnt risk are high because of no chimney and hot flue gas temperature is still higher than 200 degree C, very cheap in construction, and environmentally causes impact on local deforestation. This paper attempted to design, construct, and run a set of combustion test to NWS Stove for boiling gambir using mixture of biomass fuel of fire-wood, palm fiber and shell. It was made of river stones and consists of two main parts, namely combustion chamber with grate for biomass fuel bed and its pot and flue gas heat utilization. Water Boiling Test was conducted with the height of grate of 25 to 45 cm from the floor, natural or forced convection air underneath the grate, damper between combustion chamber and flue gas channel to the chimney was 10 to 20 cm height opened, and kinds and mixtures of biomass with any quantitative proportion. The result shows that the stove is green and saves the fire-wood fuel 70% or more. It also shows performances as follow: higher heat transfer efficiency, namely up to 18.78%; very simple in operation and long service life; gives more benefits in health and safety; needs higher capital investment but low operational cost. Additionally, temperature profiles show that adjustable grate with distance to cooking pot not more than 25 cm probably plays an important role in effective heat transfer.
