The experiments were set up to investigate the effects of evaporator length on their heat transfer characteristics by tested on different heat input (60, 70 and 80 oC) and various lengths (Le: 150, 300 and 400 mm). The results illustrated in Figure 5, for length of 100, 150 and 300 mm, it has significant influence on heat flux of condenser. The best length to heat flux was 100 mm