On typical sized homes, we install “fan” type headering system as shown in the photos.  This not only  insures that the flow rates are the same thru each loop installed, but conserves the amount of space taken up below grade.  On retrofit systems, this is also important as the amount property disturbed during construction of the loop field is kept to a minimum. For example, on a 4-ton system, the only space required is a 15′ x 15′ square, and “fan” is placed directly in the middle of the square. We can also horizontal bore under the foundation wall from the location of the loop field into the mechanical room of the home.  Again, keeping the disturbance to a minimum.