There are several designs which able to transfer the requested heat between double pipe heat exchanger fluids. This paper shows how to do design for double pipe heat exchanger and estimate inner pipe diameter, and length of the tubes. The heat exchanger fluids in this paper are water, and the inner and outer tubes are made from carbon steel. A comparative was made between the theoretical data obtained for the designed heat exchanger and the turbulent models in computational fluid dynamics (CFD) codes. The heat exchanger dimensions were made in ANSYS workbench. The theoretical distributions of hot and cold water temperature along the length of the counter flow double pipe heat exchanger matching well with distributions using k-ɛ standard turbulent model of ANSYS