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
Advantages
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
Disadvantages
Initial cost
Design
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)
Construction
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
normal