Joe,

Your best bet would be to consult a Geothermal HVAC installer in your area. There are a lot of variables which would effect the answers to your questions.

Generally, Trenching would be the least expensive but most obtrusive or damaging. Following trenching would be horizontal boring and then vertical well or shafts. That is if a pond or lake is not used for the loop.

what is the most economical horizontal loop configuration. Tonnage is 3 and 4 for two units. The loop pipe to be 3/4 with a 1 1/4 manifold. What would be best layout for equal flow in each line, separation from each other and depth of supply and return. Current depth will be at 5 to 6 feet. Please advise thanks