DRILLING-SITE SEQUENCE · EDUCATIONAL

From locate marks to a commissioned loop.

Vertical closed-loop installation sequence: nine steps, each grounded in a public standard or guideline, ending where the loop meets the heat pump's hydraulic strip. Play the sequence or step through it.

Open the sequence See the unit it connects to

Example site, not a job record

An educational sequence for a vertical closed-loop ground heat exchanger, shown as a generic example site. It is not a Polar Bear job record, and Polar Bear Water Source Heat Pumps Mfg. Inc. is documented here as the equipment manufacturer only; loop design, drilling and grouting are performed by qualified loop contractors and drillers under the standard and permits that apply to the site.

ANIMATED SEQUENCE

Nine steps, one example site.

The scene is a schematic cross-section. Depths, spacing, drilling method and materials are unspecified until a site design exists. Reduced-motion users get static step views.

STEP 1 / 9Ready.

No audio. Nothing downloads or plays automatically.

STEP REFERENCE

The same nine steps in print form.

Each step's principle, the cited wording behind it and what remains unspecified.

Step 1

Site investigation and utility clearance

The building's heating and cooling loads and the ground's thermal properties set how much pipe the site needs. Buried utilities must be located and marked, and permits obtained, before the ground is disturbed.

Cited wording

“Soil thermal values shall be used in calculating loop length.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1B.3
“For larger, commercial projects in which the heat exchanger will be installed vertically, the thermal properties of the soil/rock formation shall be determined by performing a thermal conductivity (in-situ) test.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1B.3 (2004)
“Local and state laws and ordinances as they pertain to buried pipe systems shall be strictly followed or a variance obtained.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1A.3
“At least 5 business days before you dig, submit a locate request.” — Homeowners: Public Utility Locates, Homeowners page
“Requesting a locate through Ontario One Call is free.” — Homeowners: Public Utility Locates, Homeowners page

Unspecified until a site design exists

Number, depth and spacing of boreholes
Loop layout and pipe size
Local permits and setbacks
Whether a thermal conductivity test is required for the project size

Step 2

Rig setup

The drilling rig is set over each marked bore location, inside the locate marks and outside any required setbacks. Access, cuttings containment and water supply are arranged before drilling starts.

Cited wording

“The following table describes the minimum recommended distances between components of the GSHP and pertinent ground features.” — Ground Source Heat Pump Installation and Design Guideline, Appendix A
“A vertical geothermal heat exchanger comprised of a borehole, closed-circuit high-density polyethylene pipe, and a self-sealing, low permeability grout is not a well.” — Geothermal Boreholes Are NOT Wells, Article

Unspecified until a site design exists

Rig type and size
Setback distances for the site
Site protection and traffic plan

Step 3

Drilling and cuttings management

The borehole is drilled to the design depth with a diameter large enough for the loop assembly and the grout tremie pipe. Drill cuttings and fluids are contained and disposed of properly. The drilling method depends on the geology and is chosen by the driller.

Cited wording

“All boreholes shall have a minimum diameter large enough to accommodate the specified ground heat exchanger assembly and tremie pipe, or as dictated by the authority having jurisdiction.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.1.1
“For a vertical system, holes (approximately four inches in diameter) are drilled about 20 feet apart and 100 to 400 feet deep.” — Geothermal Heat Pumps, Vertical
“Tailings from well drilling operation should be properly disposed.” — Ground Source Heat Pump Installation and Design Guideline, 13.c

Unspecified until a site design exists

Drilling method (depends on formation)
Actual borehole depth and diameter for the site
Cuttings disposal route

Step 4

Loop placement

A high-density polyethylene pipe assembly with a factory U-bend at the bottom is pressure-tested, then lowered with the tremie pipe all the way to the bottom of the borehole. No field joints are made on the vertical pipe.

Cited wording

“Into these holes go two pipes that are connected at the bottom with a U-bend to form a loop.” — Geothermal Heat Pumps, Vertical
“After drilling, the ground heat exchanger assembly and tremie line shall be completely inserted to the bottom of the borehole.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.2.2.1
“Only factory joints should be used on vertical piping.” — Ground Source Heat Pump Installation and Design Guideline, 10.b
“All loops will be pressure tested with culinary water before installation into the borehole.” — Ground Source Heat Pump Installation and Design Guideline, 11.b

Unspecified until a site design exists

Pipe diameter and dimension ratio
Weighting method for the assembly
Pre-insertion test pressure for the project

Step 5

Grouting

Grout is pumped through the tremie pipe from the bottom of the borehole to the surface in one continuous operation, keeping the tremie outlet below the rising grout. Grout protects the aquifer against water movement between layers and gives thermal contact between the pipe and the formation. Backfilling with cuttings is not acceptable.

Cited wording

“After ground heat exchanger assembly and tremie insertion, vertical boreholes shall be grouted from bottom to top in a single, continuous operation with pressure tremie grouting methods.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.2.2.1
“The tremie pipe discharge shall be submerged below the grout level during the grouting operation.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.2.2.1
“Vertical boreholes shall be grouted within 24 hours of being constructed.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.2.2.2
“Grouting materials shall be certified and listed according to NSF/ANSI Standard 60, “Drinking Water Treatment Chemicals - Health Effects” and have known heat transfer capacity and an adequate sealing characteristic.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2B.3.1
“When drilling and placement of the heat exchanger system are completed, the grout is pumped into the borehole through a temporary ‘tremie’ pipe, filling it from the bottom to the surface.” — Geothermal Boreholes Are NOT Wells, Article

Unspecified until a site design exists

Grout material, thermal conductivity and mix for the site
Top-off procedure after settling
Whether the authority requires a thermally enhanced grout

Step 6

Headers and trenching

Trenches connect the borehole pipes to supply and return headers running to the building. Buried polyethylene is joined by heat fusion, the method illustrated here, or by stab-type fittings that meet the cited clause's quality requirement; sharp rocks are kept off the pipe, and each circuit is pressure-tested before it is covered.

Cited wording

“The only acceptable methods for joining buried polyethylene pipe systems are: 1) a heat fusion process or 2) stab-type fittings quality controlled to provide a leak-free union between pipe ends that is stronger than the pipe itself.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1D.1
“Backfilling procedures will include prevention of any sharp-edged rocks from coming into contact with the pipe by removal of the rocks before backfilling.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2A.2
“After each circuit has been assembled, including connection to the boreholes or horizontal loops, and before backfilling; and” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.7.1
“Tracer wire and tracking tape should both be placed to mark the location of all horizontal pipes.” — Ground Source Heat Pump Installation and Design Guideline, 13.f

Unspecified until a site design exists

Header layout, reverse-return or manifold arrangement
Trench depth and bedding for the site
Fusion method and qualification records

Step 7

Piping into the building

The header pipes enter the mechanical room, insulated where they run near the wall, and are terminated near the circulator position, capped and left under pressure. The final hydraulic connection to the heat pump waits until the ground heat exchanger has been flushed, purged and pressure-tested separately from the building system.

Cited wording

“All buried GHP pipes in systems containing an antifreeze and passing parallel within 5 feet (1.524 m) of any wall, structure, or water line shall be insulated with R2 minimum closed cell insulation.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 2A.4
“The heat exchanger system purging shall be completed separately from the building system.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.2
“Ground-source systems employ either open-loop designs (drawing groundwater through wells) or closed-loop systems (circulating antifreeze solution through buried pipes in vertical, horizontal, or diagonal configurations).” — Heating and cooling with a heat pump, Ground-source systems

Unspecified until a site design exists

Antifreeze type and concentration
Wall penetration detail and insulation
Where the loop terminates relative to the circulator and unit

Step 8

Testing, flushing and purging

Each circuit is flushed in both directions at a velocity high enough to carry air and debris out, then the whole ground heat exchanger is pressure-tested before it is connected to the building system. It is left filled with clean water under pressure until final connection.

Cited wording

“Each supply and return circuit shall be flushed and purged in the forward and reverse directions with water at a minimum velocity of 2 ft/sec (0.6096 m/sec) through each piping section. Flow must be maintained for a minimum of 15 minutes in each direction to remove all debris and air.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.2
“The maximum test pressure shall be 1.5 times the design static pressure less the elevation hydrostatic head.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.5.1
“Where the design static pressure is not known, a default value of 100 psi (690 kPa) may be used.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.5.1.1
“after the complete ground heat exchanger system has been installed, flushed and purged of air and debris, and before the entire ground heat exchanger system is connected to the building system.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.7.2
“The duration of the pressure test shall be no less than 1 hour after the stabilization of pressure.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.8
“After the conclusion of the ground heat exchanger pressure test, the ground heat exchanger shall be left filled with clean water and maintained under pressure until final connection to the building system.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.8 (2013)

Unspecified until a site design exists

Purge pump size and flow for the header design
Project test pressure
Record format required by the authority

Step 9

Final connection and commissioning

With the loop proven, the circulator and the heat pump's source connections are made up at external unions outside the cabinet; legacy practice places the circulator in the piping just outside the heat pump. The building side is filled and purged, then flow rate and entering and leaving water temperatures are read and compared with the design. Legacy Polar Bear units ship with a flow meter and thermometers for this purpose. Documentation of the as-built loop, fluids and test results is part of the current standard's scope.

Cited wording

“In almost all Polar Bear Heat Pumps, the Wilo circulators used in, “Closed Loop Applications”, are installed in the piping just outside the Heat Pump, not mounted on the wall.” — Philosophy for Polar Bear Web Site (historical design philosophy), Circulator Pumps
“Polar Bear provides (2) thermometers with large red L.E.D. indicators which display the incoming and exiting temperatures.” — Philosophy for Polar Bear Web Site (historical design philosophy), Flow Meter and Temperature Thermometers
“by multiplying the gallons per minute by 500 lbs., times the temperature differential between the water solution entering the heat Pump and the temperature of the Water exiting the Heat Pump, the amount of free energy absorbed or collected from the earth can be easily calculated.” — Philosophy for Polar Bear Web Site (historical design philosophy), Flow Meter and Temperature Thermometers
“Flow rates and pressure drops will be compared to calculated values to assure that there is no blockage or kinking of any pipe. If actual flow rate or pressure drop values differ from calculated design values by more than 10 percent, the problem shall be identified and corrected.” — Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition, 1E.3
“The standard covers minimum requirements for equipment and material selection, site survey, system design, installation, testing and verification, documentation, and commissioning and decommissioning.” — CSA/ANSI/IGSHPA C448 Series:25, Design and installation of ground source heat pump systems for commercial and residential buildings, Scope

Unspecified until a site design exists

Connection sizes at the unit
Design flow and temperature difference for the selected model
Thermostat and control setpoints
Owner documentation package for the jurisdiction

Connect to the two-section conceptThe loop ends at the core's hydraulic strip: source in and out at external unions.What happens inside the unitSource water, refrigerant and air paths in the cabinet.Documented legacy modelsCapacities at the stated entering water temperatures.

REFERENCES

Sources

Primary standards, public guidance and the manufacturer document quoted in the sequence. The 2017 IGSHPA edition is archived; the current CSA/ANSI/IGSHPA C448 standard governs.

Geothermal Heat Pumps ↗U.S. Department of Energy, Office of Geothermal. Consumer overview of horizontal and vertical closed loops.
Closed-Loop/Geothermal Heat Pump Systems Design and Installation Standards, 2017 edition ↗International Ground Source Heat Pump Association. Archived edition. IGSHPA states these standards were sunset in May 2025 and refers readers to CSA/ANSI/IGSHPA C448. Cited here for its explicit procedural clauses; the current standard governs.
CSA/ANSI/IGSHPA C448 Series:25, Design and installation of ground source heat pump systems for commercial and residential buildings ↗CSA Group, ANSI and IGSHPA (bi-national standard). Current standard. Its scope covers equipment and material selection, site survey, system design, installation, testing and verification, documentation, commissioning and decommissioning.
Geothermal Boreholes Are NOT Wells ↗Geothermal Exchange Organization, 21 November 2013. Explains borehole, U-bend pipe and grout construction.
Homeowners: Public Utility Locates ↗Ontario One Call. Ontario example of a mandatory locate service; other jurisdictions have their own requirements.
Ground Source Heat Pump Installation and Design Guideline ↗Salt Lake County Health Department (Utah). Example of a local jurisdiction guideline; cited for procedure wording only, not as a rule that applies elsewhere.
Heating and cooling with a heat pump ↗Natural Resources Canada. Refrigeration cycle and ground-source loop overview.
Philosophy for Polar Bear Web Site (historical design philosophy)Dennis Campbell, Polar Bear Water Source Heat Pump Mfg. Inc.. Legacy manufacturer document; describes supplied flow meter and thermometers and external circulator placement.