- Contact information
- If you have questions about installing geothermal systems or applying for a heat exchange drillers license, contact:
- DNR Geothermal Hydrogeologist
Heat exchange drilling (geothermal systems)
Heat exchange drilling in Wisconsin requires a license.
Geothermal works on the principal of using the earth's natural underground temperature and a geothermal heat pump unit to provide heating in the late fall, winter and early spring and cooling in the late spring, summer and early fall. In Wisconsin, the average underground temperatures range from about 52 degrees in the south to 42 degrees in the north. Below about 20 feet in depth, the influence of surface temperature variations begins to dissipate rapidly and becomes the average of all surface temperature values.
Four basic types of geothermal systems are allowed in Wisconsin:
- A closed loop vertical system has the loops installed in a vertical or angled drillhole.
- A closed loop horizontal systems has the loops installed in a shallow trench or angled drillhole.
- A pass-through system or "pump and dump" draws water from a well and discharges it back to a surface source.
- A direct exchange (DX) system has loops typically made of copper and are installed in a vertical or angled drillhole.
Constructing heat exchange drillholes
Any geothermal system that involves construction of one or more drillholes extending more than 25 feet below the ground surface must meet construction standards and notification or approval requirements in NR 812, Wis. Adm. Code. In addition, heat exchange drillholes may only be constructed by a licensed Heat Exchange Driller or a Registered Heat Exchange Drill Rig Operator working for a licensed driller.
Heat exchange drilling projects require a prior DNR approval if any of the following conditions apply to the project:
- Ten or more drillholes
- Drillholes greater than 400 feet deep
- Project within 400 feet of a municipal well
- Project in Outagamie County
- Project in Winnebago County
Use the Closed Loop Heat Exchange Well Application (Form 3300-255) to apply for DNR approval. If none of the above conditions apply to the project, a Heat Exchange Notification number is required prior to construction.
Apply for a heat exchange driller license
All applicants must submit:
- Individual Heat Exchange Driller License Application (Form 3300-300) and
- Experience Voucher For Individual Heat Exchange Applicant (Form 3300-301) - to document drilling experience in Wisconsin.
Drillers seeking reciprocity for licensing in another state must also complete the Out-of-State Individual Heat Exchange Driller License Application (Form 3300-302).
All applicants must take the written exam. You will be notified of your eligibility to take the exam along with further instructions regarding study materials, fees, exam and other logistics. Learn more about the heat exchange driller licensing process.
- Exam Review Webcast
- NR 146 (registration) and NR 812 (well construction) summary revisions
- NR 146 Well driller and pump installer registration
- NR 812 Well construction and pump installation
- Drilling and Well Construction
- Buoyancy Related to Vertical Loop Installations
- Bedrock Geology of Wisconsin (free download)
- Bedrock stratigraphic units in Wisconsin (free download)
- Glaciation in Wisconsin (free download)
- Drilling Fluids: Tips and Tricks for Summertime Tremie Grouting
- An Overview of Geothermal Grouts (You must create a free account on the National Driller website to view the article)
- PE Pipe Joining procedures (Plastic Piping Institute - Chapter 9)
- Environmental Remediation Drilling Safety Guidelines (National Groundwater Association)
- Flowing Well Handbook
- Best Practices for Vertical Closed-Loop Installations (Michigan DEQ)
- A Builders Guide to Geothermal Heat Pumps
- Guide to Federal Tax Incentives for Residential Heat Pump Systems
- Geothermal Heat Pumps - U.S. Department of Energy