Daikin WDC Installation, Operation And Maintenance Manual page 46

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