A Korean civilian attached to the 51st Civil Engineer Squadron heating, ventilation, air condition and refrigeration shop tightes a nut at Osan Air Base, Republic of Korea, Aug. 14, 2014. HVAC-R are responsible for installing, maintaining, repairing and operating furnaces, boilers, stoves, heat exchangers, burners, blowers, fans and radiant heaters. (U.S. Air Force photo by Senior Airman Matthew Lancaster)