U.S. Air Force Master Sgt. John Wanner from the 446th Civil Engineer Squadron monitors the gauges on an M-80 water heater used in expeditionary base kitchens and latrines during a field exercise at Tyndall Air Force Base, Fla. on May 25, 2011. Sergeant Wanner is one of 30 Reservists from the 446th CES participating in Silver Flag 2011, a week-long training exercise designed to improve the readiness capability of Air Force civil engineers. Sergeant Wanner, of Olympia, Wash. is the HVAC (heating, ventilation and air conditioning) shop supervisor with the 446th CES. (U.S. Air Force photo by Staff Sgt. Grant Saylor/Released)