MIL-HDBK-1125/1, MILITARY HANDBOOK MAINTENANCE AND OPERATION OF CENTRAL HEATING PLANTS. The purpose of this handbook is to provide information and guidance on installation, operation, and maintenance of US Navy central boiler plant equipment. Efficient plant operation becomes more important with each increase in cost of fuel and equipment. The central plant operator has an important job in achieving and maintaining maximum efficiency of plant operation. Information and guidance in this handbook should be reviewed as a first step toward achieving efficient plant operation.