Commissioning Phases


  1. Planning
  2. Design
  3. Construction
  4. Occupancy / Operations

Approval from DNR or other governing body or Authority Having Jurisdiction (AHJ)
Formation & Thermal Conductivity (TC) Test to determine ground properties

Field Test


  • Drill to desired depth
  • Use same pipe diameter and grout
  • Wait 5 days
  • Insulate entire device
  • Minimum test length = 48 hours

Thermal Conductivity Test


  • Indicates level of effort required to insert loop
  • Type of drilling
  • Reduce Contractor’s uncertainty
  • May reduce bid price
  • Can use test bore in design


  • Initial cost

What to Look For
Qualifications: Geothermal contractor certified by IGSHPA

  • As-built drawings of geo field required (including GPS coordinates)
  • F&TC Test results
  • Contractor to integrate test bore into the geothermal field
  • Pipe and fittings shall be HDPE classified for geothermal installation (IGSHPA)
  • 50 year warranty provided by pipe manufacturer
  • Heat transfer fluid must be approved by DNR or State Regulatory Agency
  • Locating Wire and Warning Tape
  • Thermal Grout: TC of at least 1.0 Btu/hr-ft-F (obtain samples for testing)

Before Excavation Begins

  • Contractor Qualifications
  • Shop drawings must be approved prior to ordering materials or starting work
  • DNR and/or State Regulatory Agency approval
    Timing is critical During Excavation / Drilling / Pipe Installation
  • Bore spacing / depth
  • Materials on site: pipes, grout, backfill materials, vault, etc.
  • Lateral pipe (trench) depth – below frost line
  • Grouting Procedure
    • Must grout within 24 hours of drilling. No more than four un-grouted boreholes at any one time.
    • Test grout mixture samples early.
  •  Seal open ends of pipes to prevent entry of contaminants
    Timing of verification is critical
Occupancy / Operations

System Maintenance

  • Borefield is essentially maintenance-free
  • Verify glycol concentration
  • Verify system pressure
  • Check fluid temperatures – range of 30F to 100F is
  • Annual check of vault interior (if applicable)