Closed Loop Geothermal FAQ
A closed loop system uses a continuous loop of buried polyethylene pipe. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which an environmentally friendly antifreeze-and-water solution is circulated. A closed loop system constantly re-circulates its heat-transferring solution in pressurized pipe, unlike an open loop system that consumes water from a well. Most closed loops are trenched horizontally in areas adjacent to the building. However, where adequate land is not available, loops are vertically bored. Any area near a home or business with appropriate soil conditions and adequate square footage will work.
Closed loop systems also can be vertical. Holes are bored up to 250 feet per ton of heat pump capacity, depending on where you live. U-shaped loops of pipe are inserted in the holes. The holes are then backfilled with a sealing solution.
Closed loop systems should be installed using only high-density polyethylene pipe. Properly installed, these pipes will last for many decades. They are inert to chemicals normally found in soil and have good heat conducting properties. PVC pipe should never be used.
Trenches are normally four to six feet deep and up to 400 feet long, depending on the number of pipes in a trench. One advantage of a horizontal loop system is being able to lay the trenches according to the shape of the land. As a rule of thumb, 500-600 feet of pipe is required per ton of system capacity. A well-insulated 2,000-square-foot home would need about a three-ton system with 1,500 - 1,800 feet of pipe.
Pipe sections are joined by thermal fusion. Thermal fusion involves heating the pipe connections and then fusing them together to form a joint that's stronger than the original pipe. This technique creates a secure connection to protect from leakage and contamination.
No. Research has proven that loops have no adverse effect on grass, trees, or shrubs. Most horizontal loop installations use trenches about 24 inches wide. This, of course, will initially leave temporary bare areas, but they can easily be restored with grass seed or sod. Vertical loops require little space and result in minimal lawn damage.
1,800 to 2,500 sq. ft homes typically require 2 trenches with 2 loops each running 300 ft at a depth of 6 feet. The trenches don't have to be straight but need to be away from septic beds
Rock conducts core earth energy well so if we can lay the loops on rock it won't require the full 6 feet of depth. In many locations we can add extra fill for additional depth. The other option is to drill vertical boreholes in these area
1,800 to 2,500 sq. ft homes typically require 3 or 4 boreholes ranging in depths from 150 to 200+ feet each. It's not as daunting as it sounds using today's drilling equipment.
Yes, if it's deep enough and large enough. A minimum of six feet in depth at its lowest level during the year is needed for a pond to be considered. The amount of surface area required depends on the heating and cooling load of the structure. You should opt against using water from a spring, pond, lake or river as a source for your heat pump system unless it's proven to be free of excessive particles and organic matter. They can clog a heat pump system and make it inoperable in a short time.
It's not recommended. Good earth-to-coil contact is very important for successful loop operation. Nonprofessional installations may result in less-than-optimum system performance.
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