McQuay WGS190AW User Manual

OM WGS-5 WGS 130A to 190A 49
Transitions:
T1 – Transition from Off to Start
Requires any of the following
 Unit state = Auto AND any circuit available AND LWT error > Startup Delta
 Cond Water Freeze Alarm
T2 – Transition from Start to Run
 Flow ok for time > cond recirculation timer setpoint
T3 – Transition from Run to Off
Requires all of the following
 Unit state = Off OR No circuit available OR LWT error < Start Delta-1
 Cond Water Freeze Alarm not active
 No compressors running
T4 – Transition from Start to Off
Requires all of the following
 Unit state = Off OR No circuit available OR LWT error < Start Delta
 Cond Water Freeze Alarm not active
 No compressors running
T5 – Transition from Run to Start
Requires all of the following
 Condenser water flow loss for time > flow proof
 All circuits in Off state
Pump Selection
The pump output used will be determined by the Condenser Pump Control setpoint. This
setting allows the operator to select pump #1, pump #2, or auto. The first two selections
will use a single pump output all the time. The auto selection will start the pump with the
least run hours.
The selected output will be ON if the Evap State is set to START or RUN. Both outputs
will be OFF if the Evap State is set to OFF.
Cooling Tower Control
Tower Fans
Tower fan control is active when the unit is set up as water-cooled, Tower Control is set to
Temperature, and the condenser pump is in the RUN state. Staging is based on Condenser
Entering Water Temperature. Operation depends on the following parameters.
 Condenser pump state
 Condenser EWT
 Stage up and stage down timer values
 Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time,
Stage Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @)
When the condenser pump starts, the stage up timer shall start. The first stage shall turn ON
when the following conditions are met:
 The stage up timer completes
 The Condenser EWT is > Stage #1 ON setpoint
 Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint
= Valve Stage)
 VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = VFD
Stage OR Valve SP/VFD Stage)

McQuay WGS190AW Specifications

General

Brand	McQuay
Model	WGS190AW
Category	Chiller
Language	English