History of District Heating in the United States

| Chronological List of District Heating Systems in the United States |

District Heating in Chicago, Illinois

The Western Edison Light Co. was founded in Chicago in 1882, three years after Thomas Edison developed a practical light bulb. In 1887, Western Edison became the Chicago Edison Co. Samuel L. Insull became president of Chicago Edison in 1892; in 1897 Insull incorporated another electric utility, the Commonwealth Electric Light & Power Co. In 1907, Insull's two companies formally merged to create the Commonwealth Edison Co.


Steam Plants of the Illinois Maintenance Company in 1915	1932 Map of Illinois Heating Company Steam Plants from NDHA Handbook (Second Edition)	1951 Map of Illinois Heating Company Steam Plants from NDHA Hanbook (Third Edition)

References
1900 "New Illinois Corporations," The Inter Ocean, January 27, 1900, Page 11.
Springfield, Jan.26. Illinois Maintenance company, Chicago; capital stock $50,000; incorporators E.H. Cheney, Waldo F. Tobey, and George C. Madison.

1900 "Illinois Maintenance Company," Western Electrician (March 24, 1900)

1915 District Heating: A Brief Exposition of the Development of District Heating and Its Position Among Public Utilities, by S. Morgan Bushnell and Frederick Burton Orr
Page 14: Map showing plants operated by the Illinois Maintenance Company in downtown Chicago.

1951 District Heating Handbook, Third Edition, National District Heating Association
Page 13: Chicago, Illinois.—In Chicago the Illinois Maintenance Company operates an interconnected block system of district heating. In this type of system a group of several buildings is heated by a boiler plant located in the basement of one of them. Pipes are usually run through the basements to connect the heating systems of the various buildings. Several such groups are then interconnected into larger systems.
The company serves approximately 80 customers with about 1,445,000 sq. ft. of equivalent direct radiator surface, heating 133,000,000 cu. ft. of space. The distribution system contains 14,000 ft. of mains and services and 9,000 ft. of condensation return piping. In 1930, 794,062,000 lb. of steam were sold.
There are two principal disadvantages to the block system, first, the inefficiency of the small basement plants and, second, the distribution of steam by means of an insecure right-of-way through consumers’ premises. However, if a large system were contemplated in Chicago, some of the elements of the block system would be retained. The location of the boilers in basements has some advantage because the plants are located at various points of the distribution system and the pipe sizes may therefore be kept relatively small.
Page 14: Map of the Illinois Maintenance Company system (see above)

1951 Handbook of the National District Heating Association (Third Edition)
Page 13: Chicago. In Chicago the Illinois Maintenance Company operates three separate steam systems. These have been developed by installing tie lines between former block systems, thereby forming an interconnected system of production and distribution. The boiler plants are either owned or leased, and all but one are located in the basements of the larger office buildings. Steam is generated and distributed at pressures of 115 to 135 psi. Most of the steam and return pipes are located in building basements or subsidewalk space.
Steam is generated in six boiler plants, four of which are tied together into one system. Connections are also maintained with boiler plants not operated by the Company, for the purpose of receiving or supplying emergency service. In the system comprising the four plants, one is operated 24 hours per day for base load and the others as needed to pick up the peak loads resulting from weather changes. There is no by-product generation of electricity.
The company serves many of the important buildings in the Loop, including office structures, theatres, department stores, restaurants, shops, etc., but does not supply industrial requirements except a relatively small amount for water heating, cooking, candy making, laundering, and pressing.
During the next ten years it will be necessary to rebuild some of the older boiler plants, thereby giving some added capacity for new business.
Although the service has not been developed in Chicago to the extent it has been developed in other large cities, it is the largest interconnected block type system in operation. This type of system has limitations as well as advantages. The location of the boilers in basements situated at various places on the system with piping principally through building basement and subsidewalk space affords the means of providing smaller pipes, with lower capital investment in both plants and distribution system. The system can not be expanded greatly beyond these plants, however, and the smaller boilers are more costly to operate.
In some cities the advantages of the block system have been combined with the more conventional system by installing some piping through customers’ premises and utilizing basement boilers for peak load and reserve capacity.
Page 140: Map of Illinois Maintenance Company system (see above)

1962 Insull: The Rise and Fall of a Billionaire Utility Tycoon, by Forrest McDonald
Pages 26-27: The bankers believed that the proper market was for so-called isolated plants: systems designed for lighting a single large building and operated from a "powerhouse" in the basement, much as a steam-radiator system is operated. This method had the short-range virtues of requiring small capital outlay and promising quick returns, whereas Edison's plan for central stations was slow, risky, and expensive. Edison conceded that isolated plants could be sold to help raise money for developing his first central station, as well as for their incidental publicity; and for this reason he formed the Edison Company for Isolated Lighting, which licensed local organizations in major cities with the exclusive right to sell Edison equipment in their areas. But this was only a stopgap concession, for Edison was unalterably convinced that the great future for electricity lay in central service. The bankers were as cool toward the central station as Edison was toward isolated plants and, having advanced and received no returns on upwards of $500,000, they absolutely refused to advance any more for either Edison's central station or the sizeable manufacturing works that Edison's route would entail.