John Thielmann & Son Inc in Hartford, WI has been serving customer since 1929! We offer Heating, Geothermal, Air Conditioning services. We are proud to have the following certifications and affiliations - Insured, Licensed. We accept the following forms of payment: Licensed & Insured, Licensed - Insured, Discover Card, VISA, All Major Cards Accepted, Always Financing Available, Always - Financing Available, American Express, MasterCard. We have been proudly serving the Hartford, WI area since 1929.