131
damper will be increased proportionally. As the CO
2
level
decreases because of the increase in fresh air, the outdoor-air
damper will be proportionally closed. For EconoMi$er IV and
X operation, there must be a thermostat call for the fan (G). If
the unit is occupied and the fan is on, the damper will operate at
minimum position. Otherwise, the damper will be closed.
When the EconoMi$er IV and X control is in the occupied
mode and a call for cooling exists (Y1 on the thermostat), the
control will first check for indoor fan operation. If the fan is not
on, then cooling will not be activated. If the fan is on, then the
control will open the EconoMi$er IV and X damper to the min
-
imum position.
On the initial power to the EconoMi$er
®
IV and X control, it
will take the damper up to 2
1
/
2
minutes before it begins to posi-
tion itself. After the initial power-up, further changes in damper
position can take up to 30 seconds to initiate. Damper move
-
ment from full closed to full open (or vice versa) will take
between 1
1
/
2
and 2
1
/
2
minutes. If free cooling can be used as
determined from the appropriate changeover command
(switch, dry bulb, enthalpy curve, differential dry bulb, or dif
-
ferential enthalpy), then the control will modulate the dampers
open to maintain the mixed-air temperature set-point at 50°F
(10°C) to 55°F (13°C). If there is a further demand for cooling
(cooling second stage — Y2 is energized), then the control will
bring on compressor stage 1 to maintain the mixed-air tempera
-
ture set-point. The EconoMi$er IV and X damper will be open
at maximum position.
2-Speed Note: The EconoMi$er IV and X controller will adjust
the damper position as the Indoor Fan Speed changes, per its
configured values.
Heating
The sequence of operation for the heating is the same as an
electro-mechanical unit with no economizer. The only differ
-
ence is how the economizer acts. The economizer will stay at
the Economizer Minimum Position while the evaporator fan is
operating. The outdoor-air damper is closed when the indoor
fan is not operating. Refer to Service and Maintenance Manual
for further details.
Optional Perfect Humidity™ dehumidification system
Units with the factory equipped Perfect Humidity system
option are capable of providing multiple modes of improved
dehumidification as a variation of the normal cooling cycle.
The Perfect Humidity system option includes additional valves
in the liquid line and discharge line of each refrigerant circuit, a
small reheat condenser coil downstream of the evaporator, and
variable-speed control of some or all outdoor fans. Operation of
the revised refrigerant circuit for each mode is described below.
The Perfect Humidity system provides three sub-modes of
operation: Cool, Reheat1, and Reheat2.
Cool mode — Provides a normal ratio of Sensible and Latent
Cooling effect from the evaporator coil.
Reheat1 — Provides increased Latent Cooling while slightly
reducing the Sensible Cooling effect.
Reheat2 — Provides normal Latent Cooling but with null or
minimum Sensible Cooling effect delivered to the space.
The Reheat1 and Reheat2 modes are available when the unit is
not in a Heating mode and when the Low Ambient Lockout
switch is closed.
Refer to the following figures for single stage and 2 stage pip-
ing flow diagrams.
RTU Open controller (factory option)
For details on operating 582/559K units equipped with the
factory-installed RTU Open controller option, refer to Factory
Installed RTU Open Multi-Protocol Controller Controls, Start-
Up, Operation and Troubleshooting manual.
NORMAL COOLING MODE — PERFECT HUMIDITY™
SYSTEM WITH SINGLE STAGE COOLING
CONDENSER COIL
PERFECT HUMIDITY
COIL
EVAPORATOR COIL
COMPRESSOR
OUTDOOR AIR
INDOOR LEAVING
AIR
INDOOR ENTERING
AIR
RDV
VALVE
CLV
VALVE
REHEAT MODE
METERING
DEVICE (TXV)
= CLOSED VALVE
= OPEN VALVE
SUBCOOLING MODE (REHEAT 1) — PERFECT HUMIDITY
SYSTEM WITH SINGLE STAGE COOLING
RDV
VALVE
CLV
VALVE
CONDENSER COIL
PERFECT HUMIDITY
COIL
EVAPORATOR COIL
COMPRESSOR
OUTDOOR AIR
INDOOR LEAVING
AIR
INDOOR ENTERING
AIR
REHEAT MODE
METERING
DEVICE (TXV)
= CLOSED VALVE
= OPEN VALVE
HOT GAS REHEAT MODE (REHEAT2) — PERFECT
HUMIDITY SYSTEM WITH SINGLE STAGE COOLING
RDV
VALVE
CLV
VALVE
CONDENSER COIL
PERFECT HUMIDITY
COIL
EVAPORATOR COIL
COMPRESSOR
OUTDOOR AIR
INDOOR LEAVING
AIR
INDOOR ENTERING
AIR
REHEAT MODE
METERING
DEVICE (TXV)
= CLOSED VALVE
= OPEN VALVE
Sequence of operation (cont)
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