Horizontal Loop    Advantages:      * Lower cost            * No drilling permits required      * No contaminates such as bentonite      * Requires substantial land area (approx. 2000 ft per ton)    Disadvantages      * Moisture content of soil is key factor      * Excavation can be disruptive to existing landscaping

Mat Loop Advantages: Simpler design; lower drilling; more efficient performance by avoiding thermal degradation associated with heat transfer across pipe wall from ground or water body to antifreeze solution in closed-loop; lower installation cost is a supply well already exists for domestic water or grounds irrigation, with sufficient surplus production capacity to supply heat pump system. Disadvantages Subject to local, state and federal groundwater and surface water withdrawal and discharge permitting; large water flow requirements may exceed local water availability; supply-side of heat exchangers subject to corrosive and abrasive agents, chemical scaling, and microbial fouling; main circulating pumps typically require more power in open loops than in closed loops; water discharge regulations may preclude single-well systems or constrain the design of standing-column systems; higher installation cost if a separate injection well is required for loop water discharge.

Pond Loop      * Stainless Steal Plates      * Coil application is traditional      * Good thermal transference      * Requires 1 acre plus water surface      * Requires 10 ft - 15 ft water depth      * Needs to have stable annual water levels

Hybirds & Open Loop

In open-loop GHP systems, a groundwater or surface water supply is used as a direct heat transfer medium, such that the water flows "one-way" through the building heat pump units and is then discharged. Not used in California due to regulatory issues, Hybrid systems using water irrigation systems can be utilized.