You can think of an earth loop as a rechargeable battery permanently connected to a battery charger. Heat energy is drawn from the loop, or “battery,” as it is needed in your home. If the battery is large enough, it is easily recharged by the heat energy from the surrounding ground, sun, rain, heat expelled during the cooling of your home, and heat emanating from the earth’s hot core. But if your loop battery is continuously drawn down more quickly than it can be recharged, it will be unable to provide enough energy to run your system. And there is no easy way to recharge it quickly.

So the ground loop has to meet the requirements of your home. Someof the factors that will affect the size of the ground loop you need include:

the heating and cooling requirements of your home;
the moisture content and type of soil;
the depth at which the loop is buried;
the climate;
the amount of snow covering the loop in winter; and
the size of the buried pipes as well as the distance between them.

The larger the heating and cooling loads of your home, the larger the loop must be. Moist, dense soil conducts heat more quickly than light, dry soil. Pipe that is buried deeper has more soil to draw heat from and will perform better. A climate with long cold spells will require a loop (“battery”) that can hold more heat. Heavy snow cover insulates the earth and helps retain the earth’s heat.

If earth loop pipes are buried farther apart, they are recharged by a greater mass of soil.

A competent contractor will know the soil conditions in your area, and will design the earth loop on the basis of all these factors.

By far the most important step a homeowner needs to take when considering a GSHP system is to work with a reputable and experienced installer. Such an installer will ensure that the system is properly designed and installed so as to maximize system efficiency and homeowner comfort. A good installer will make sure that following problems are avoided:

It is essential that a GSHP system be carefully designed to meet the projected building load (heating and cooling demands). A GSHP system that is undersized will cost less upfront, but will perform poorly, causing overly high electric bills. Short ground loops (water wells that are not deep enough for standing column wells, boreholes that are not deep enough, or trenches that are not long enough) are one source of under-sizing a GSHP system. The heat pump equipment itself can also be under-sized, causing poor performance and high electric bills. Another source of under-sizing can be the system piping; if pipes are too small, the efficiency of the entire system will suffer, again resulting in lower efficiency and higher electric bills.

The GSHP systems can also be oversized. An oversized ground loop will cost more than necessary, causing higher upfront costs. Oversized heat pump equipment, while also costing more than necessary, will cycle on and off too rapidly, causing inefficient performance and higher electric bills. Therefore, it is essential that the homeowner get their GSHP system installed by an experienced and reputable installer, preferably one that comes highly recommended by past customers. .