Senior Airman David Ulman, 436th Civil Engineer Squadron, Heating, Ventilation, and Air conditioning section, uses two wrenches to open a valve on a heater unit inside of Dorm 430 while troubleshooting a problem on Jan. 15, 2015, at Dover Air Force Base, Del. (U.S. Air Force photo/Greg L. Davis)
Senior Airman David Ulman, 436th Civil Engineer Squadron, Heating, Ventilation, and Air conditioning section, pours dirty water from a heater unit out on the ground near Dorm 430 while troubleshooting a problem on Jan. 15, 2015, at Dover Air Force Base, Del. Trapped water inside the heater unit didn't allow heat to be transferred by the unit. (U.S. Air Force photo/Greg L. Davis)
Senior Airman David Ulman and Staff Sgt. Jordan Weaver, 436th Civil Engineer Squadron, Heating, Ventilation, and Air Conditioning section, move to their next location while troubleshooting a heating problem in Dorm 430 on Jan. 15, 2015, at Dover Air Force Base, Del. The pair has to flush individual heating units to allow fresh heated water to be cycled through them. (U.S. Air Force photo/Greg L. Davis)