Daikin WGZ030DW Operating And Maintenance Manual page 68

Water-cooled = Y
SET TOWER SPs (4)
Valve/VFD Control=
ValveSP/VFDStage
Valve Type=NC to Twr
Valve/VFD Control settings are None, Valve Setpoint, Valve Stage, VFD Stage, or ValveSP/VFDStage.
Default is None which results in no control of the tower from the MicroTech II controller.
Valve Setpoint, the valve will control (bypass tower) to hold the minimum temperature as established by
the Set Tower SPs in screen (5) below.
This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint OR Valve SP/VFD
Stage. In this mode the valve output is varied with a proportional-derivative (PD) algorithm (with
deadband) in order to maintain the controlled parameter (CP) at the desired value. The output is always
limited between the Valve Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A
valve increment shall be computed once every 5 seconds according to the following equation. (Error Gain
and Slope Gain are set in menu screen #8.)
Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)]
Where: Error = ECWT – Valve Setpoint
Slope = (Present CP) – (Previous CP)
When the Error is > the Valve Deadband setpoint, the valve position analog output (% of full scale) is
updated according to the following equation.
New %Position = Old %Position + Increment/10
Valve Stage, controls from the fan stage setpoint in use. It is recommended that the Valve Setpoint
method explained above be used rather than this mode.
This mode is only operational when the Valve/VFD Control setpoint is set to Valve Stage. In this mode
the valve output is controlled as for Valve Setpoint mode (above), except that the active setpoint for the
controlled parameter is selected according to the following table.
# Of Fans ON
VFD Stage, ValveSP/VFDStage, When the Valve/VFD Control setpoint is set to None, Valve Setpoint,
OR Valve Stage, this output is set to 0. Otherwise, it will be controlled in a manner identical to Valve
Stage Mode (above) except that (1) it shall be kept at zero until the first fan stage is ON, and (2) the
following setpoints do not apply.
Valve Control Range (Min)
Valve Control Range (Max)
Valve Type
Valve Type settings are NC (normally closed to tower) or NO (normally open).
These settings establish the operation of a tower bypass valve (must be a 3-way valve).
Initial Valve Position
When the condenser pump is not in the RUN state, the valve output shall be set as a function of entering
condenser water temperature (ECWT) per the following graph.
68
Active Setpoint
0 Valve Setpoint
1 Stage #1 ON
2 Stage #2 ON
3 Stage #3 ON
4 Stage #4 ON
WGZ030D through WGZ200D OMM 1130-2