A GXS draws heat from the earth. Burying a ground loop for a GXS requires excavation around your home. Other services are usually buried in the ground already, including electrical cables, water lines, sewer lines, septic fields and gas lines, that must be avoided when you dig. There may be trees and shrubs that you would prefer not to disturb. On a smaller property, it may be impossible to get to the best possible site with heavy equipment like a backhoe or large, truck-mounted drill rig.
Sometimes there are alternatives. In some areas it may be possible to drill boreholes deep enough to cause only minimal disturbance of a yard, or drill the boreholes with a compact drill rig that can reach the site easily. A chain trencher may be small enough to fit into the backyard.
Make sure you know the type of equipment the contractor is planning to use, and that both you and the contractor understand exactly where the loop will be located. Many contractors will mark the location of the earth loop with small flags or spraypaint markers on the ground.