Surface Water Closed System
Surface water closed loops are used when property is located by a body of water such as a pond, lake or ocean and may be the most economical. GeoExchange experts recommend this only if the water level never drops below six feet. The pipes are coiled into a slinky design then submerged in the water with no adverse impact on the aquatic system. The design works like the closed ground loop system with fluid running through polyethylene piping while drawing or returning energy from the water.
Open Loop system applications are best where a house is or will be served by its own well water. This GeoExchange system main considerations are the availability of water and the water discharge. Quality of water must be in the plan as some well water can cause corrosion to the heat pump. Always call in a GeoExchange expert to consult with the well driller to have water analyzed. Wells are typically six inches in diameter and can be as deep as 500 feet. The size of the heat pump unit and the manufactures specifications will determine the amount of water that is needed for an open system. Typically open systems require 6 -15 gallons per minute. Your well and pump combination should be large enough to supply the water needed by the heat pump and for your domestic water requirements. Local environmental officials should be consulted to determine if restrictions apply in your region.
Horizontal Ground Closed Loop System
Horizontal ground closed loop systems are the most cost effective when adequate property space is available. The pipe is placed into trenches 3 to 6 feet deep using trenchers or backhoes. Generally 400 to 600 feet of pipe per ton of heat pump capacity is required. A typical 2000 sq. foot home needs a three ton system (1200 to 1800 feet of pipe). The pipes are laid in a parallel series (most common) or if trenches have to be shorter, pipes may be curled in a slinky shape. Some GeoExchange designs can use four or six pipes in each trench if limited yard space. Modern digging equipment now allow horizontal boring with minimal disturbance to your property and even under existing buildings or driveways.
Vertical Ground Closed System
Vertical ground closed system are incorporated when property space is limited and are ideal for most new suburban applications or retro fits. Holes are drilled vertically into the earth 60 to 300 feet deep. A series of u-shaped pipes are inserted and connected to horizontal pipes running to the interior heat pump. The amount of holes vary with the capacity required by the heat exchanger. The holes are filled with a sealing solution or backfilled . Vertical systems require less piping as the temperature is more stable year round deep in the earth.