What should be used when two pipes are separated by a short distance?

When two pipes are separated by a short distance, the best choice is to use a union. A union provides a means of connecting two pipes together while allowing for easy disconnection. This is particularly valuable in plumbing and piping systems where maintenance or repairs may be needed in the future. Unlike other connection types, a union can be unscrewed and reassembled without having to cut the pipes, making it an efficient option for short-distance connections where access is confined.

In contrast, while an elbow is useful for changing the direction of pipes, it does not offer a disconnect feature and is not designed for connecting two parallel pipes. Similarly, a nipple or coupling can serve as a connector, but it lacks the convenience of a union in terms of future disassembly. The bell reducer, intended for connecting pipes of varying diameters, is not applicable here since the scenario specifies that both pipes are the same size and only a short distance apart. Thus, the union stands out as the most appropriate choice for this situation.