Daikin Navigator WWV - Unit Enable and Disable Control; Unit Mode Selection Logic; Unit Control States Overview

31
IOM 1264-4
WWW.DAIKINAPPLIED.COM
OPERATION
Unit Enable
Enabling and disabling the chiller is accomplished using set
points and inputs to the chiller. The Unit Switch, Remote Switch
Input, and Unit Enable Set Point all are required to be On/Enable
for the unit to be enabled when the control source is set to Local.
The same is true if the control source is set to Network, with the
additional requirement that the BAS Enable set point be Enable.
Table 26: Enable Combinations
Unit
Switch
Control
Source
Set Point
Remote
Switch
Input
Unit En-
able Set
Point
BAS
Request
Unit State
O󰀨 - - - - Disable
- - - Disable - Disable
- - O󰀨 - - Disable
On Local On Enable - Enable
- Network - - Disable Disable
On Network On Enable Enable Enable
All of the methods for disabling the chiller, discussed in this
section, will cause a normal shutdown of any running circuits.
Unit Mode Selection
The operating mode of the unit is determined by set points and
inputs to the chiller. The Available Modes Set Point determines
what modes of operation can be used. This set point also
determines whether the unit is congured for glycol use. The
Control Source Set Point determines where a command to
change modes will come from.
The Available Modes Set Point must only be changed when the
unit switch is o󰀨. This is to avoid changing modes of operation
inadvertently while the chiller is running. Unit Mode is set
according to the following table.
Table 27: Unit Mode Combinations
Available Modes
Set Point
Control
Source
Set Point
Mode
Input
BAS
Request
Unit Mode
Cool - - - Cool
Cool/Ice Local O󰀨 Cool
Cool/Ice Local On Ice
Cool/Ice Network Cool Cool
Cool/Ice Network Ice Ice
Ice - - - Ice
Glycol Conguration
If the Evaporator Glycol Set Point is set to a value ‘Yes’, then
glycol limits should be enabled for the unit. This means that
various pressure and temperature settings can be set to lower
values as a result of the glycol limits being enabled. Once
glycol limits are enabled, they should only be disabled when the
Evaporator Glycol Set Point is set to ‘No.’
Unit Control States
The unit will always be in one of three states:
1. O󰀨 – Unit is not enabled to run
2. Auto – Unit is enabled to run
3. Shutdown – Unit is doing a normal shutdown
T1 - O󰀨 to Auto. All of the following are required:
• Unit is enabled per the Unit Enable section
• No alarms requiring shutdown are active (except for auto
cleaning ow loss alarms)
• Circuit is available to start
• Unit conguration is valid
• Mode is Cool, Heat
• Mode is Ice with no Ice Start delay