Hyatt Regency Atlanta, Central Plant

The Response

Two existing chiller plants were consolidated into a single chiller plant, and a hydronic economizer was incorporated. The project included the installation of two new chillers (500-ton and 800-ton capacity), and condenser and chilled water pumps. The chillers were pre-purchased based on a life cycle cost analysis, including first cost, chiller energy, pump energy, and maintenance costs. The chilled water control system optimizes overall plant energy efficiency.

Control system features include:

• Condenser water reset based on ambient wet bulb temperature.
• Variable-primary chilled water distribution.
• Chilled water temperature reset.
• Continuous calculation of plant operating efficiency (hourly, daily, weekly and monthly, kW/ton) for benchmarking.
• Cooling tower de-ice mode (used with hydronic economizer).
• Condenser water flow reset based on the number of active chillers and load.

The hotel was originally configured with two separate steam boiler plants: low pressure and high pressure. The plants were consolidated into a single low-pressure boiler plant.

• The removal of existing chillers during the earlier chiller plant replacement cleared space to allow the new steam boilers to be installed in the low-pressure boiler plant. Removing the high-pressure plant allowed the hotel to use this room for a new emergency generator.
• Four new 300-hp flexible tube steam boilers were The boilers were shipped in knockdown construction form for field assembly.
• Distribution piping was reconfigured and pressure reducing stations were removed to allow the elimination of high-pressure steam.
• Two boiler flue exhaust systems were installed to permit the boilers to be vented using the existing flue routing to the roof.
• Boiler system controls include oxygen trim control and boiler integration to the BAS.

Key contributors to the success of the project included the Hyatt Regency Atlanta Engineering Department, CleaverBrooks, Custom Mechanical Systems Inc., Siemens Building Technologies, The Trane Company, and Womack & Associates.