Daikin EWAQ340GZXR [40/78] Pump selection

Daikin EWYQ320GZXR [40/78] Pump selection
D-EOMHP00706-14EN - 40/78
6.2 Pump selection
The pump output used will be determined by the Evap Pump Control set point on HMI. This setting allows
the following configurations.
HMI setting
Description
#1 Only
Pump 1 will always be used
#2 Only
Pump 2 will always be used
#1 Primary
Pump 1 is used normally, with pump 2 as a backup
#2 Primary
Pump 2 is used normally, with pump 1 as a backup
Auto
The primary pump is the one with the least run hours, the other is used as a backup
The Primary / Standby selection will be designated with the least hours.
6.3 General unit control
6.3.1 Circuit Staging Sequence
This section defines which circuit is the next one to start or stop. In general, circuits with fewer starts will
normally start first, and circuits with more run hours will normally stop first. Circuit staging sequence can
also be determined by an operator defined sequence via set points. The next circuit to start or stop must
meet the following requirements.
Priority
Next Start
Next Stop
1st
Lowest sequence number
Lowest sequence number
2nd
Least starts
Least starts
3rd
Least run hours
Most run hours
4th
Lowest numbered circuit
Lowest numbered circuit
6.3.2 Unit capacity control
6.3.2.1 Summary of unit capacity control
Unit capacity shall be controlled by LWT error and EWT pulldown rate.
• If there is limitation (i.e. network limit, current limit, event limit,) that limitation should be priority.
• The target variation is plus or minus 4% of nominal evaporator delta T
• Just one circuit can load or unload per load or unload command.
• Capacities of each circuit shall be balanced when possible.
6.3.2.2 LWT error
“LWT error” will be calculated to determine the circuit start up, shut down, stage up or stage down and
the compressors loading or unloading. The equation of LWT error varies based on Unit mode.
[For cooling]
LWT error = Evaporator LWT LWT active set point
[For heating]
LWT error = LWT active set point Evaporator LWT
LWT active set point will be determined by LWT set point on HMI and LWT resetting.

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