Abstract: A condenser is formed from a plurality of pipes connected to a header with each pipe formed to define a lowermost straight portion on which a plurality of convoluted further straight portions are provided in the same vertical plane. Each straight portion is connected to the next by a curved connecting portion of a radius of curvature substantially equal to the spacing between each straight portion and the next straight portion so that the connecting portion extends to a height above the upper straight portion to which it is connected to. This ensures that each straight portion acts as a liquid trap to retain the condensate therein with the condensate and gas being bubbled over each connecting portion to move into the next liquid trap. The gas is injected at the lower header and the liquid extracted at the upper header. This tends to keep the inner surface of the pipe wetted with the condensate thus improving heat transfer and reducing the overall size of the condenser.