Which transition fitting connects vertical piping in a GSHP well to horizontal piping?

The transition fitting that connects vertical piping in a Ground Source Heat Pump (GSHP) well to horizontal piping is indeed a pit-less adapter. This fitting is specifically designed for use in well applications where it allows easy access to the well without needing to extract the entire vertical section of the piping.

The pit-less adapter serves a crucial role by providing a watertight seal and facilitating a smooth transition between the vertical rise of water from the well and the horizontal distribution of that water for heating or cooling purposes in a GSHP system. By using a pit-less adapter, you ensure that there is minimal disturbance in the well and maintain the integrity of the well structure, which is essential for its proper function.

Other options do not fulfill this specific requirement. A coupling simply connects two sections of piping but does not account for vertical to horizontal transitions. An elbow fitting can change the direction of piping but is not designed for direct transitions between vertical and horizontal installations. A union fitting allows for easier disconnection of piping sections but, like coupling, does not cater specifically to the unique needs associated with well applications.