Daikin MicroTech III Operation Manuals page 129

Table 60: Dehumidification Staging
Stage
Comp
# 1
0 OFF
1 ON
2 ON
3 ON
Stage
Comp
# 1
0 OFF
1 ON
2 ON
3 ON
4 ON
* Note: A 20 second delay will be provided after unloading compressor #1 or #2 prior to starting Compressor #3 or Compressor #4.
Pumpdown
Pumpdown is accomplished by closing the liquid line solenoid
valve on a circuit and operating a compressor on that circuit
until the circuit low pressure switch opens . The compressor
pumps most of the refrigerant into the condenser and then
shuts OFF .
When pump down is required for a circuit, the liquid line
solenoid valve for that circuit is closed (its output is OFF)
and a compressor operates until the low pressure switch
opens at which time the compressor is turned OFF . If the low
pressure switch does not open in 180 seconds, pump down is
terminated by turning OFF the compressor and its unloaders .
If a compressor in a circuit is operating, the circuit is pumped
down when the last compressor is to shut OFF due to normal
staging, or when the pump down switch for that circuit is placed
in the Pumpdown (Open) position, or when the circuit or entire
unit is shutdown due to any alarm other than the High Pressure
Alarm . Of course, the conditions for completing pump down
are met if the low pressure alarm shuts down the circuit so no
pump down occurs as a result of this alarm .
Pumpdown is also initiated if no compressors are operating
in a circuit, and the Pumpdown Switch is moved from the ON
(Auto) position to the OFF (Pumpdown) position twice in less
than 20 seconds, and the low pressure switch is closed . In this
case the first compressor on the circuit is used to pump down
the circuit .
If two compressors on one circuit are operating when pump
down is required for that circuit, the lag compressor in that
circuit is turned OFF immediately and the circuit is pumped
down using the lead compressor .
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Two Compressors and Six Stages (CompCfg=4 & Cond Ctrl=2 or 3)
Circuit # 1
Liq Line Valve Comp # 1
# 1 Unl # 2
OFF OFF
ON ON
ON ON
ON OFF
Four Compressors and Eight Stages (CompCfg=E & Cond Ctrl=2 or 3)
Circuit # 1
Liq Line Valve Comp # 1
# 1 Unl # 2
OFF OFF
ON OFF
ON OFF
ON ON*
ON ON
Comp # 1 Comp
Unl # 1 # 2
OFF OFF
ON ON
OFF ON
OFF ON
Comp # 1 Comp
Unl # 1 # 2
OFF OFF
ON ON
OFF ON
ON ON
OFF ON
If any unloaders on a reciprocating compressor are de-
energized when that compressor is required for pump down,
they are energized and the circuit is pumped down using one
completely unloaded compressor .
NOTE: A reciprocating compressor is mechanically
prevented from pumping down the circuit if the oil
pressure switch is open .
Sump Pump Control
The Sump Pump Output is turned ON whenever the unit
is in the Cooling state and the Sump Water Level Input is
present (ON) . The Sump Pump Output is turned ON before
any compressor or condenser fan is turned ON . The Sump
Pump Output remains ON for 10 minutes (adjustable) after unit
leaves the Cooling operating state before turning OFF as long
as the Sump Water Level Input is present (ON) .
A Sump Water Level problem alarm is generated if the unit has
been in the Cooling operation state for 5 minutes and the Sump
Water Level Input is not present (OFF) . If this occurs, the Sump
Pump output is turned off and mechanical cooling is disabled .
To prevent problems related to Sump Water Level Switch
fluctuations, there is a 5 second "to OFF" time on the switch.
If Dolphin= Yes, the sump pump is run every day to reduce
scaling . The Sump Pump Output is turned ON for one hour if
all of the following are true:
• Dolphin System= Yes
• Sump Pump Output has been off for more than 24 hours
but less than 120 hours .
• The OAT is greater than 35°F .
• The Sump Drain Valve is closed .
129 OM 920-6 • MICROTECH UNIT CONTROLLER
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peraTor
Circuit # 2
Liq Line Valve Comp # 2
# 2 Unl # 2
OFF OFF
ON ON
ON ON
ON OFF
Circuit # 2
Liq Line Valve Comp # 2
# 2 Unl # 2
OFF OFF
ON OFF
ON OFF
ON ON*
ON ON
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Comp # 2
Unl # 1
OFF
ON
OFF
OFF
Comp # 2
Unl # 1
OFF
ON
OFF
ON
OFF