This video demonstrates the approach to take when modeling a closed-loop system. The first approach involves including a reservoir node in line with pipes and fittings to allocate fluid pressure and temperature. The model also includes a pump and heat exchanger, and it shows similar results to the second approach, where we split the model at the reservoir and use two non-pressure boundary elements. This video also provides a solution to the warning that occurs when placing a boundary or reservoir outside of the main closed loop.