History of District Heating in the United States

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

District Heating in Tulsa, Oklahoma

Thermal Systems, Inc., a wholly-owned subsidiary of Oklahoma Natural Gas Company, built heating and cooling plants in downtown Tulsa and Oklahoma City. The system in Tulsa began service in June 1970. The system was sold to Trigen in 1989 and to Vicinity Energy in 2019.

.References
1970 "New Heating-Cooling System being constructed in Oklahoma," District Heating 55(3):17 (Winter 1970)
Oklahoma City, Thermal Systems, Inc. subsidiary of Oklahoma Natural Gas Company

1970 "Thermal Delivers First Major Order," Tulsa World, June 9, 1970, Page 9.
Thermal System Inc. made its first big delivery of chilled water Monday for air conditioning of downtown buildings. The delivery was to the Oklahoma Natural Gas Co. building. customer of the system, actually, was Central Plaza Apartments Saturday.