Time to switch cooling to heating Published Oct. 28, 2008 By 81st Civil Engineer Squadron KEESLER AIR FORCE BASE, MISS. -- It's one of the two annual periods when facilities are switched back and forth between heating and cooling. Many newer facilities have four-pipe systems that can provide heating and cooling year-round automatically, but most older facilities have a two-pipe system that can only cool or heat at any one time and must be manually switched. The two-pipe systems take about eight days to shift from heating to cooling and three days to convert from cooling to heating. The waiting time is required because temperature changes can result in immediate system failure, with damage to compressors, tube ruptures and loss of refrigerant gases. Replacing refrigerant is a costly environmental concern. The decision to end cooling and start heating in older buildings is made as late as possible to minimize inconvenience. The 81st Civil Engineer Squadron works closely with lodging management, the consolidated dorm management office and other affected users to determine the best days for the changeover. Once units are switched to heating, crews begin equipment maintenance in preparation for the next cooling season. Facilities with two-pipe systems affected most by wide temperature swings in a 24-hour period: Building 823, military family housing office. Building 2101, Muse Manor. Building 2816, 81st Training Wing headquarters. Building 2901, Mathies NCO Academy. Building 2902, Airman Leadership School. Building 3101, Locker House. Building 3709, Larcher Chapel. Building 3821, Shaw House. Buildings 4430 and 4431, transportation complex. Building 7402, Triangle Chapel. 20, 48, 49 and 50 block dorms.