Carrier 48LC Series - Optional Humidi-Mizer Dehumidification System

21
Fig. 12 — Outdoor Fan Motor Arrangement
Optional Humidi-MiZer Dehumidification System
Units with the factory-installed Humidi-MiZer system option
are capable of providing multiple modes of improved dehu-
midification as a variation of the normal cooling cycle. The
Humidi-MiZer system option includes additional valves in the
liquid line and discharge line of each refrigerant circuit, a re-
heat coil downstream of the evaporator, and variable-speed
control of all the outdoor fans. The Humidi-MiZer system
equipped configuration is factory set to Yes for Humidi-MiZer
system equipped units (HUMIDIMIZER OK = YES). This en-
ables Humidi-MiZer system operating modes and service test.
Humidi-MiZer system operation requires the installation and
configuration of a relative humidity switch input or a space rel-
ative humidity sensor. The HUMIDISTAT and SPRH leads are
provided with quick connects. The Space Humidity Switch
configuration, SETTINGS  UNIT CONFIGURATIONS 
SWITCH INPUTS CONFIGS  HUMSTAT CHANNEL
identifies the normally open or normally closed status of this
input at high humidity. The Space RH Sensor configuration,
SETTINGS  UNIT CONFIGURATIONS  ANALOG IN-
PUTS CONFIGS  SPRH SENS CHANNEL, identifies to
the channel number the sensor is wired into.
DEHUMIDIFICATION DEMAND
When using a humidistat or switch input, the demand for dehu-
midification is seen as Space Humidity Switch (INPUTS 
SWITCH INPUTS HUMIDISTAT) being Low or High. A
low value means humidity level is good and a high value
means that dehumidification is needed.
When using an SPRH sensor, the demand is based on the Space
Humidity Sensor (INPUTS ANALOG INPUTS SPRH)
value compared to the Space RH Setpoint (SETTINGS 
SPACE SETPOINTS  SPRH SETPOINT). If the Space
Humidity Sensor (SPRH) value is above the Space RH Set-
point (SPRH Setpoint), then dehumidification is needed. If the
Space Humidity Sensor (SPRH) value is below the Space RH
Setpoint (SPRH Setpoint) minus the Space RH Deadband
(SETTINGS  UNIT CONFIGURATIONS  COOLING
 SPRH DEADBAND), then dehumidification is no longer
needed.
NOTE: When there is a dehumidification demand, the economizer
damper position is limited to its minimum damper position.
HUMIDI-MIZER SYSTEM MODES
With Humidi-MiZer system units, there are two additional HVAC
modes available for the user: Dehumidification and Dehum/Mech
Cooling. Selection of the Dehum/Mech Cooling mode is deter-
mined by the dehumidification demand and the cooling demand.
Tables 13 and 14 show the corresponding circuit mode and output
status for the different demand combinations.
48/50LC 24-26 48/50LC 17-20 48/50 LC14
OFM1
OFM5
OFM6
OFM4
OFM3
OFM2
Control Box Side
1
1
2
2
33
OFM1
OFM4
OFM3
OFM2
Control Box Side Control Box Side
2
1
2
1
OFM1
OFM3
OFM2
48/50LC 08-12
48/50LC 07
OFM1
OFM3
OFM2
Control Box Side
OFM1
OFM2
Control Box Side
Indicates the Outdoor
Fan Signal from the
board. Otherwise the
motor and signal match.
1
2
3
OFM
48/50LC 04-06
Control Box Side