IOM 1281-2 • CENTRIFUGAL WATER CHILLERS 46 www.DaikinApplied.com
Figure 48: Settings View - Water
Table 12: Water Setpoints
Description Default Range PW
Maximum Reset Delta-T 0.0 °F 0.0 to 20.0 °F T
Reset Type = Return: Sets the maximum LWT reset that can occur.
Reset Type = 4-20 mA: Sets amount of reset at 20 mA input.
Start Reset Delta-T 10 °F 0.0 to 20.0 °F T Sets evaporator delta-T above which Return reset begins.
LWT Reset Type None
None
Return
4-20mA
T
Reset raises LWT setpoint
Return (uses start Reset Delta T & Max Reset Delta T)
4-20 mA (4 mA=None, 20 mA=Max as set by Max Reset Delta T)
Startup Delta-T 3.0 °F 0 to 10.0 °F T
set the temperature delta below leaving water for compressor to start.
Shutdown Delta-T 1.0 °F 0 to 3.0 °F T
Sets amount leaving water must drop below setpoint for last compressor to stop. For
Stage Delta-T 1.0 °F 0 to 9.9 °F M Sets amount leaving water must go above setpoint for next compressor to start.
Leaving Water Temp - Cool 37.0 °F 35.0 to 80.0 °F O
Sets control target for evaporator leaving water temperature in COOL mode. 35 °F is lowest
setpoint for shutdown.
Leaving Water Temp - Cool
w/ Glycol or Cool / Ice
37.0 °F 15.0 to 80.0 °F O
Sets control target for evaporator leaving water temperature in Cool with Glycol or Cool /
ICE mode. When running in the ICE portion of the mode, the temperatures limit to the lower
range of 15-35 °F.
Leaving Water Temp - Ice 25.0 °F 15.0 to 35.0 °F O Sets control target for evaporator leaving water temperature in ICE mode.
Leaving Water Temp - Heat 135.0 °F 66.0 to 150.0°F O Sets control target for condenser leaving water temperature in HEAT mode.
No Start - Water Source 70 °F 30 to 100 °F O
Delta Reset - Water Source 55.0 °F 50 to 100 °F O
The Active Leaving Water variable shall be set to the current
by one of the reset methods below. (The current LWT setpoint
is Cool LWT as determined by the chiller mode.) The type of
(Setpoint 6 of the WATER Setpoint Screen).
Reset Type – NONE
The Active Leaving Water variable is set equal to the current
LWT setpoint.
Reset Type – RETURN
The Active Leaving Water variable is adjusted by the return
water temperature.
When the chiller mode = COOL, the Active Leaving Water
variable is reset using the following parameters:
1. Cool LWT setpoint
2. Max Reset Delta T setpoint
3. Start Reset Delta T setpoint
Reset is accomplished by changing the Active Leaving Water
variable from the (Cool LWT setpoint) to the (Cool LWT
setpoint + Max Reset Delta-T setpoint) when the evaporator
(return – leaving) water temperature delta varies from the (Start
Reset Delta-T setpoint) to 0.
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