The only acceptable method to connect pipe sections is by thermal fusion. Pipe connections are heated and fused together to form a joint stronger than the original pipe. Mechanical joining of pipe for an earth loop is never an accepted practice. The use of barbed fittings, clamps, and glue joints is certain to result in loop failure due to leaks.
Frequently Asked Questions
Closed-loop systems should only be installed using high density polyethylene or polybutylene 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 not be used under any circumstances.
Closed-loop systems can also be vertical. Holes are bored to about 125-150 feet per ton of heat pump capacity. U-shaped loops of pipe are inserted in the holes. The holes are then backfilled with a sealing solution.
Normally, a run of pipe is laid at five feet then looped back over itself at three feet once the bottom pipe is covered with soil. This allows more length of pipe to be put in one trench and has no adverse affect on system efficiency. Other loop designs use four or six pipes and allow for shorter trenches if land area is limited.
Trenches are normally four to six feet deep and up to 400 feet long, depending on how many pipes are in a trench. One of the advantages 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.
That depends on land availability and terrain. Most closed-loops are trenched horizontally in yards adjacent to the building. But any area near a home or business with appropriate soil conditions and adequate square footage will work.
The term “closed-loop” is used to describe a geothermal heat pump system that uses a continuous loop of special buried plastic pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which an antifreeze solution is circulated. Unlike an open-loop system that consumes water from a well, a closed-loop system recirculates its heat-transferring solution in pressurized pipe.
The buried pipe, or “ground loop,” is the most recent technical advancement in heat pump technology. The idea to bury pipe in the ground to gather heat energy began in the 1940s. It’s only been in the last few years that new heat pump designs and improved pipe materials have been combined to make geothermal heat pumps the most efficient heating and cooling systems available.
There are two main types: open and closed.
No. The same loop works for both. All that happens when changing from heating to cooling, or vice versa, is that the flow of heat is reversed.