News / 8.6.18

Installation Begins on O’Hare's New High Temperature Water System

Epstein is providing architecture and engineering services for the project

Last week, those visiting O’Hare during the early morning hours were treated to quite the site; a 90 ton high temperate water (HTW) generator being installed in the airport’s H&R Plant. This is the first major milestone in a multi-year mission to replace all of O’Hare’s generators, a project in which Epstein is serving as the architect and structural and MEP/FP engineer.

What is a HTW generator? It’s a hot water boiler, generating high pressure and high temperature. The HTW generator system at O’Hare is responsible for providing space heating and domestic hot water to the majority of the airport’s campus.

Currently, O’Hare’s Heating and Refrigeration (H&R) Plant is equipped with eight output HTW generators. Each has the capacity of 75 million Btu per hour, meaning the entire HTW generator system can generate a total of 600 million Btu per hour of high pressure (450 psi) high temperature (410° F) hot water.


O’Hare has embarked on this project because the original generators were installed between 1969 and 1988. They are either already over their expected lifetime or nearing it. Therefore, in 2012, the City of Chicago decided to replace them, along with their associated pumps, air compressor, steam generators and control system. The estimated cost of the project is $60 million

Epstein was responsible for designing and upgrading the replacement generators. Our primary project objectives include:

  • Installing heating systems with minimal disruptions to the operations of the airport
  • Minimizing life-cycle costs of airport heating systems
  • Providing heating systems of acceptable reliability and efficiency

This project also required Epstein to create the ability to manually and automatically control the new HTW generators.

Construction kicked off in January 2018, with Mechanical, Inc. serving as the general contractor. Once the first new generator arrived to O’Hare last Thursday, via truck, the process of getting it into the H&R Plant was strategically planned out. A crane and steel track had previously been set up and was ready to go. The generator was unloaded from the truck, by the crane, and placed on the track. A hydraulic machine then positioned the generator, and carefully slid it into the building.


The construction schedule of this project has five milestones and plans to be completed by the summer of 2022:

  1. Phase one, 2018 – replacing one HTW generator
  2. Phase two, 2019 – replacing two HTW generators
  3. Phase three, 2020 – replacing three HTW generators
  4. Phase four, 2021-2022 – replacing the last two HTW generators
  5. Complete HTW generator system commissioning in 2022

Once completed, the new HTW’s will be prepared to handle the proposed $8.75 billion terminal, airfield and site improvements as part of O’Hare’s grand expansions plans.