In order to use a low quality biodiesel as a burner fuel, the combustion characteristics and exhaust emissions of an agricultural warm air furnace operated with a low quality Rapeseed Oil Methyl Ester (RME_L) are investigated by comparing with a high quality one (RME_H) and Bunker A. RME_L and RME_H have the lower NO_x, SO_2 and Smoke emissions compared with Bunker A. The thermal efficiency and exhaust emissions of RME_L are almost the same as that of RME_H. Also, the carbon deposit of RME_L on the heat exchanger outlet of the agricultural warm air furnace is lower than that of Bunker A. From the experimental results, RME_L can be used as an alternative fuel for agricultural warm air furnaces.