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ManualsBrandsComfort Line Product ManualsHeating SystemSTG-1

Geothermal Applications

ClimateMaster: Smart. Responsible. Comfortable.

Carefully backﬁ ll the boreholes with an IGSHPA approved

Bentonite grout (typically 20% silica sand soilds by weight)

from the bottom of the borehole to the surface. Follow IGSPHA

speciﬁ cations for backﬁ lling unless local codes mandate

otherwise. When all U-bends are installed, dig the header

trench 4 to 6 feet [1.2 to 1.8 meters] deep and as close to the

boreholes as possible. Use a spade to break through from

ground level to the bottom of the trench. At the top of the

hole, dig a relief to allow the pipe to bend for proper access to

the header. The “laydown” header mentioned earlier is a cost

effective method for connecting the bores. Figure 8 illustrates

common vertical bore heat exchangers.

Use an IGSHPA design based software such as GeoDesigner

for determining loop sizing and conﬁ gurations.

Pond/Lake Applications

Pond loops are one of the most cost effective applications

of geothermal systems. Typically 1 coil of 300 ft of PE pipe

per ton [26 meters per kW -- one 92 meter coil per 3.5 kW

of capacity] is sunk in a pond and headered back to the

structure. Minimum pond sizing is 1/2 acre [0.2 hectares]

and minimum 8 to 10 feet [2.4 to 3 meters] deep for an

average residential home. Actual area can be 1500-3000

sq. ft. per ton [39.6 to 79.2 sq. meters per kW] of cooling.

In the north, an ice cover is required during the heating

season to allow the pond to reach an average 39°F [3.9°C]

just below the ice cap. Winter aeration or excessive wave

action can lower the pond temperature preventing ice caps

from forming and freezing, adversely affecting operation of

the geothermal loop. Direct use of pond, lake, or river water

is discouraged because of the potential problems of heat

exchanger fouling and pump suction lift. Heat exchanger

may be constructed of either multiple 300 ft. [92 meter] coils

of pipe or slinky style loops as shown in Figure 9. In northern

applications the slinky or matt style is recommended due

to its superior performance in heating. Due to pipe and

antifreeze buoyancy, pond heat exchangers will need weight

added to the piping to prevent ﬂ oating. 300 foot [92 meter]

coils require two 4” x 8” x 16” [102 x 203 x 406 mm] blocks

(19 lbs. [8.6 kg] each) or 8-10 bricks (4.5 lbs [2.1 kg] each)

and every 20 ft [6 meters] of 1-1/4” supply/return piping

requires 1 three-hole block. Pond Coils should be supported

off of the bottom by the concrete blocks. The supply/return

trenching should begin at the structure and work toward the

pond. Near the pond the trench should be halted and back

ﬁ lled most of the way. A new trench should be started from

the pond back toward the partially backﬁ lled ﬁ rst trench to

prevent pond from ﬂ ooding back to the structure.

Seal and protect the entry point of all earth coupling

entry points into the building using conduit sleeves

hydraulic cement.

Slab on Grade Construction

New Construction: When possible, position the pipe in the

proper location prior to pouring the slab. To prevent wear as

Figure 9: Typical Pond/Lake Loop Conﬁ gurations

the pipe expands and contracts protect the pipe as shown

in Figure 10. When the slab is poured prior to installation,

create a chase through the slab for the service lines with 4

inch [102 mm] PVC street elbows and sleeves.

Retroﬁ t Construction: Trench as close as possible to the

footing. Bring the loop pipe up along the outside wall of

the footing until it is higher than the slab. Enter the building

as close to the slab as the construction allows. Shield and

insulate the pipe to protect it from damage and the elements

as shown in Figure 11.

Pier and Beam (Crawl Space)

New and Retroﬁ t Construction: Bury the pipe beneath the

footing and between piers to the point that it is directly

below the point of entry into the building. Bring the pipe

up into the building. Shield and insulate piping as shown in

Figure 12 to protect it from damage.

Below Grade Entry

New and Retroﬁ t Construction: Bring the pipe through the

wall as shown in Figure 13. For applications in which loop

temperature may fall below freezing, insulate pipes at least 4

feet [1.2 meters] into the trench to prevent ice forming near

the wall.

Pressure Testing

Upon completion of the ground loop piping, hydrostatic

pressure test the loop to assure a leak free system.

Horizontal Systems: Test individual loops as installed.

Test entire system when all loops are assembled before

backﬁ lling and pipe burial.

Closed Loop Design/Installation Guidelines