Responsible for maintaining the extensive heating, air-conditioning, refrigeration and ventilation systems in hospitals. The equipment they operate includes boilers, air-conditioning equipment, diesel engines, turbines, pumps, condensers, generators, and compressors. They start up, regulate, shut down, or repair this equipment. They manually operate equipment, make adjustments, and regularly check safety devices. Routine maintenance is part of the job, such as replacing filters, lubricating moving parts, and checking air quality of the ventilation systems. Some other duties could include minor welding, minor plumbing and electrical repairs, and minor carpentry repairs to walls, roofs, windows, or ceilings.