Miniplant pyrolysis is a device that functions to convert plastic waste into fuel oil based on the steam boiling point difference. In order for the product from the pyrolysis minimplant to be more maximal and much needed a coolant / condenser to convert steam from LDPE plastic (Low Density Polyehtylee) to condensate. This condenser serves to accelerate the steam cooling process. From the design activities that have been carried out, it can be seen that the dimensions of the tube-shaped shell are made of stainless steel with a thickness of 2 mm, a length of 0.5 m, a diameter of 0.4 m that can accommodate water fluid of approximately 63 liters. In the shell will flow cold fluid in the form of water with a temperature range (T = 16°C), cylindrical shaped tube, tube made of copper with a length of 6 m as much as 2 pieces, inner diameter 0.01587 cm, tube made in the form of 16 pieces with a distance per tube equal to 5. From the test results to cool the steam from temperature 93,8 °C and 122,3°C to temperature 36 °C and 38 °C it takes approximately 45 minutes.