General Info J.M. Brennan, founded in 1932, is a mechanical contracting firm that serves the southeastern Wisconsin area. It provides design and installation of boilers, chillers, air handling units, exhausts, ventilators, sanitary sewers, water treatment plants and heat recovery systems. The company also provides piping services for food grade, refrigeration, industrial gas, underground and compressed air applications. It provides services through a team of designers, engineers, steam and refrigeration fitters and sheet metal workers. The company is family-owned and managed and utilizes a variety of equipment, including backhoes and dump trucks. J.M. Brennan also provides round-the-clock repair and maintenance services and maintains its office in Milwaukee.