The experiments were set up to investigate the effects of pipe length on their heat transfer characteristics by tested on different heat input (60, 70 and 80 oC) and various lengths (Le: 300, 450 and 600 mm). The results illustrated in Figure 5, for length of 300, 450 and 600 mm, it has significant influence on heat flux of condenser. The best length to gave highest heat transfer rate 300 mm.