Closed Loops
What is a closed loop system?
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.
What if I don’t have room for a horizontal loop?
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.
How long will the loop pipe last?
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.
How deep and long will my trenches be?
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.
How are the pipe sections of the loop joined?
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.
Will an earth loop affect my lawn or landscape?
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.
I have a pond nearby. Can I put a loop in it?
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.
Can I install an earth loop myself?
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.
Do I need separate earth loops for heating and cooling?
No. The same loop works for both. To switch heating to cooling, or vice versa, the flow of heat is simply reversed.
Does the underground pipe system reallwork?
The buried pipe, or earth loop, was an important technical advancement in heat pump technology. The idea of burying pipe in the ground to gather heat energy originated in the 1940s. New heat pump designs and more durable pipe materials have been combined to make geothermal heat pumps the most efficient heating and cooling systems available.
What types of closed loops are available?
Vertical Loops
The ideal choice when available land surface is limited. Well drilling equipment is used to bore small-diameter holes from 100 to 400 feet deep.
Pond (Lake) Loops
Very economical to install when a large body of water is available. Coils of pipe or a submersed heat exchanger are simply placed in the pond or lake.
