There are x xxx-ton chillers in a penthouse mechanical room. These chillers are Rxxx machines.Chilled water is supplied at a constant temperature to xxx penthouse air handling units and xxx basement air handling units.
Each air handling unit has a two-way valve that modulates to maintain a supply air temperature setpoint.
We recommend reprogramming the automation system to reset the chilled water temperature based on the actual cooling requirements of the supply fans (i.e., slowly reset the chilled water temperature until one of the control valves is 100% open).
The chilled water plant should be controlled as follows:
• Change controls on cooling towers to allow for lower condenser water temperatures during free cooling.
• Reset the chilled water as much as possible in cooler weather.
Issues and Concerns