About ACG

Our 4200-square-foot facility is equipped with a
WaterFurnace Synergy 3D multi-function heat pump.

ACG, Advanced Custom Geothermal, is located in Kiel, Wisconsin, and was co-founded on Oct. 1, 2007, by Dan Walsdorf and Sean Steffes. They combined Walsdorf Heating and Cooling LLC and Advanced Custom Air LLC. While Walsdorf passed on the ownership to Steffes in 2017, he remains on the board.

Dan Walsdorf, left, and Sean Steffes are partners in Advanced Custom Geothermal LLC.ACG was co-founded in 2007 by Dan Walsdorf, left,
and Sean Steffes. In 2017, Walsdorf
passed on the ownership to Steffes
but remains on the board, performing all of
the duties he has in the past.

ACG is a member of the Wisconsin Geothermal Association and a member of the Mid-Shores Home Builders Association. We are partners with Focus on Energy, ENERGY STAR and Alliant Energies.

Not only do we believe in geothermal, we use it for our WaterFurnacehomes and business. In late 2008, we opened a new 4200-square-foot facility, equipped with a WaterFurnace Synergy 3D multi-function heat pump that heats water for radiant applications as well as heating and cooling with forced air.

We’d love to have you visit to see it in operation and to learn more about how geothermal will work for you — at home or at work.


ACG, LLC | P.O. Box 255 | Kiel, WI 53042
920-894-3999 | FAX 920-894-1389


  2014 GEO Member LogoServing customers in the communities of Reedsville, Lomira, Plymouth, Sheboygan Falls, Hilbert, Brillion, Kewaskum, Theresa, Kohler, Kiel, Chilton, New Holstein, Appleton, Sheboygan, Howards Grove, Elkhart Lake, Fond du Lac, Manitowoc, Calumet, Sherwood, Cleveland, Valders, St. Nazianz, Fredonia, Cedar Grove, Belgium, West Bend, Cascade, Waldo, Ripon, Rosendale, Eden, Newton, School Hill, St. Cloud, Wrightstown, Kaukauna, and Kimberly and throughout the counties of Brown, Calumet, Dodge, Fond du Lac, Green Lake, Jackson, Juneau, Kewaunee, Manitowoc, Milwaukee, Outagamie, Ozaukee, Shawano, Sheboygan, Washington, Waushara and Winnebago.

Site Design by MBF Communications
(c) 2013-14 Advanced Custom Geothermal LLC