Horizontal Closed Loop System

If adequate land is available, horizontal loops can be installed.  One or more trenches are dug using a backhoe or chain trencher.  Polyethylene pipes are inserted and the trenches are backfilled.  There are various designs of horizontal loops, using one, two or three circuits in a trench.  The more pipe per foot of trench, the shorter the trench can be.  Trenches normally range from 100 to 300 feet depending on the design.  A typical home requires 1/4 to 3/4 of an acre for the trenches.

Vertical Closed Loop System

Vertical loops are used where space is limited or the soil conditions are not conducive for horizontal loops.  Installing vertical loops requires the use of a drilling rig.  Multiple holes are bored about 10 feet apart.  A double pipe connected with a U-bend is inserted into each hole.  The hole is filled with grout to provide good contact around the pipe and to seal the hole.  The vertical pipes are then connected to a header system horizontally a few feet below the surface.  The depth of the holes is dependent upon soil/rock conditions and the size fo the system.  Although most holes are bored about 100 to 250 feet deep, there is no "magic depth" that needs to be reached.  Capacity is not based on depth; rather how much pipe is in the ground and the overall thermal conductivity of the borehole.          

Pond Closed Loop System

If an adequately sized body of water is close to your home, a pond loop can be installed.  A series of closed loops can be coiled and sunk to the bottom.  A 1/2 acre, 8-foot-deep pond is usually sufficient for the average home.  Ideally, the pond should be closed to the home (less than 200ft).  If the pond is farther from the home, the benefit of using a pond loop is reduced due to added trenching, materials and plumbing costs.  Pond loop coils are connected together on dry land, and then floated into location.  Once filled with fluid, they will sink to the bottom and remain there.  Generally, a 300 ft. coil is used for each ton of capacity.  This is less pipe than is used in an earth loop because water is a better conductor of heat energy.  Pond loops are a cost effective way to install a geothermal system, because trenching is limited to only the supply and return piping from the pond to the house.