Recently, I was asked by a company whether two loops or four loops can be used in each borehole. Has anyone had experience using four loops in one hole?? Based on past experience, I understand two loops to be a reasonable limit for looping within one borehole. As systems are used dominantly to handle the summer peaks, the ground temperatures have shown some upward creep of the soil temperatures. Since heat transfer occurs in both directions, it is important to maximize surface area of the loops for conductivity through grouting and soils. By adding loops, within one borehole, the contact with the soil is cut in half (one loop to two loops) or in quarters (one loop to four loops). I believe the cost savings of few boreholes compared to the reduced effectiveness of the system's heat transfer, the upward creep of ground temperatures, and increased pumping to attain the same BTU transfer from the loop system does not sound justified. Can anyone explain their experience?