Types of Geothermal Heating and Cooling Systems
Closed Loop - With a closed loop Geothermal system, water or
some type of antifreeze solution is pumped continuously through
underground piping, absorbing mild temperatures from the Earth
or a pond and transferring it to the home in summer for cooling
and reverse in winter for heating. These loops of tubing can be
run either horizontally at depths of five to eight feet or vertically
to a depth of a few hundred feet. The choice of using a horizontal
or vertical system will depend on the availability of space and the
cost of installation, although a vertical system is generally more
Open Loop - An open loop Geothermal system uses water
pumped through the system from a water source. Heat is then
extracted from the water before it is discharged back to the
source in winter, and reverse in summer. A consistent supply of
good, quality water is most important to the open loop
Geothermal system. (Pond or Well Water)
Types of Closed Loop Systems
Depending on the size of the property, closed-loop systems may
be installed in a variety of ways:
Vertical Loop (most common):
For smaller-sized lots, the loops can be installed vertically using
a drill rig. The rig bores holes to about 250- 300 feet per ton of
heat pump capacity. U-shaped loops of pipe are inserted into the
holes, then backfilled with a sealing solution (grouting material).
A horizontal loop is used on large lots (typically acreage).
Excavation includes digging the trenches and installing the pipe
without disturbing landscaping immediately near the home.
Pond Loop (can be open or closed):
Pond or lake loops are another type of system, which is
very cost-effective since excavation is limited to trenching
between the home and pond/lake. In a Pond loop, polyethylene
pipe is sunk at the bottom of the pond and fluid is circulated
through the pipe to exchange heat between the geothermal heat
pump and the body of water. As a general rule, the body of
water must also be within 300 feet of your home/structure.
The pond must have a minimum depth of 8-10 feet at its lowest
level during the year to be considered.
Generally, a minimum of a half-acre pond is required to provide
adequate surface area for heat transfer.