Primary States (Waterside Economizer Sequencer) - Metasys - Johnson Controls - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help
Product
Controls > Control Tools > Controller Configuration Tool
Document number
LIT-12011147
Version
15.0
Revision date
2022-11-18
Table 1. Waterside Economizer Supported States
State Chiller Selector Hx Selector Tower Enable Chiller Iso Valves Hx Iso Valves Tower Bypass Valve Tower Fans CWS-Tsp Source
Off Disabled Disabled Disabled Closed Closed 100% to Tower 0% Chiller
Chiller Control Enabled Disabled Enabled Open Closed Control Control Chiller
Stop Chillers Disabled Disabled Enabled Open Closed Control Control Chiller
Start Hx Disabled Enabled Enabled Closed Open 100% to Tower 100% Hx
Hx Control Disabled Enabled Enabled Closed Open Control Control Hx
CHWS-T Timing Disabled Enabled Enabled Closed Open Control Control Hx
Warm CW-T Disabled Enabled Disabled Closed Open 0% to Tower 0% Chiller
Start Chillers Enabled Enabled Enabled Open Open Control Control Chiller
Stop Hx Enabled Disabled Enabled Open Closed Control Control Chiller
  • Off: The chillers and heat exchangers are off.
  • Chiller Control: The chillers are in control. The towers and tower Bypass Valve are controlled to the chiller (mechanical cooling) condenser water temperature setpoint.
  • Stop Chillers: The chillers are disabled.
  • Start Hx: The heat exchangers are enabled. The cooling tower Bypass Valve supplies 100% flow to towers. The tower fan is run at 100% to cool the condenser water temperature as quickly as possible to the condenser water temperature setpoint. The condenser water temperature setpoint is the economizer condenser water temperature setpoint. If the condenser water temperature does not cool down to the condenser water temperature setpoint within the condenser water temperature Cooldown Time, the sequencer will enter the Hx Control state regardless.
  • Hx Control: The heat exchangers are in control. The towers and tower Bypass Valve control to the economizer condenser water temperature setpoint.
  • CHWS-T Timing: If the chilled water supply temperature rises above the chilled water supply temperature setpoint + chilled water supply temperature setpoint differential during heat exchanger control, the sequencer will enter this state and wait the chilled water supply temperature Wait Time before advancing toward chiller control. If the chilled water supply temperature drops to or below the chilled water supply temperature setpoint within the chilled water supply temperature wait time while in this state, the sequencer will return to heat exchanger control.
  • Warm CW-T: The cooling towers are disabled. The cooling tower Bypass Valve supplies 0% to the tower to warm the condenser water temperature as quickly as possible to the condenser water temperature Chiller Start Setpoint so the chillers can start. The condenser water temperature setpoint is the chiller condenser water temperature setpoint.
  • Start Chillers: The chillers are enabled.
  • Stop Hx: The heat exchangers are disabled.