Carrier 48LC Series Controls, Start-Up, Operation And Troubleshooting page 22

DEMAND AND MODE
Circuit Cooling
Space Humidity
Demand
—
No
Low
Yes
Yes
High
No
Space Humidity Circuit Cooling Demand
—
Low
High
NORMAL COOLING
For 48/50LC04-06 units, refrigerant flows from the outdoor
condenser and is diverted at the energized Reheat Liquid Valve
(RLV) and flows through the de-energized Cooling Liquid
Valve (CLV) to the expansion device bypassing the reheat con-
denser coil. The RDV is closed (see Fig. 13)
For 48/50LC07-26 units, refrigerant flows from the outdoor
condenser through the de-energized 3-Way Liquid Diverter
Valve (LDV) to the expansion device bypassing the reheat con-
denser coil. The Reheat Discharge Valve (RDV) is closed. (See
Fig. 14.)
DEHUM/MECH COOLING (SUBCOOLING MODE)
This mode increases latent heat removal and decreases sensible
cooling compared to normal cooling.
For 48/50LC*04-06 units, refrigerant flows from the outdoor
condenser through the de-energized Reheat Liquid Valve
(RLV) and through the reheat condenser coil to the expansion
device. The Reheat Discharge Valve (RDV) and Cooling Liq-
uid (CLV) are closed. (See Fig. 15.)
For 48/50LC*07-26 units, refrigerant flows from the outdoor
condenser, through the energized 3-Way Liquid Diverter Valve
(LDV) and through the reheat condenser coil to the expansion
device. The Reheat Discharge Valve (RDV) is closed. (See
Fig. 16.)
DEHUMIDIFICATION (HOT GAS REHEAT MODE)
This mode provides maximum latent cooling with little to no
sensible capacity. This mode can operate to provide dehumidi-
fication when there is no cooling demand.
Table 13 — Humidi-MiZer System Control Modes (Sizes 04-06)
Circuit Mode
— No power
Off
Cool
Dehum/Mech
Cooling
Dehum
Table 14 — Humidi-MiZer System Control Modes (Sizes 07-26)
DEMAND AND MODE
—
No
Yes
Yes
No
OUTPUTS
Circuit
RDL Valve
Compressor
Off Off (closed)
Off Off (closed)
On Off (closed)
On Off (closed)
On On (open)
Circuit Mode Circuit Compressor
No power
Off
Cool
Dehum/Mech Cooling
Dehum
For 48/50LC*04-06 units, The refrigerants flows from the out-
door condenser, through the de-energized RLV and through the
reheat condenser coil to the expansion device. The Cooling
Liquid Valve (CLV) is closed. (See Fig. 17.)
For 48/50LC*07-26 units, the refrigerant flows from the out-
door condenser, through the energized 3-Way Liquid Diverter
Valve (LDV) and through the reheat condenser coil to the ex-
pansion device. (See Fig. 18.)
For 48/50LC*04-26 units, the Reheat Discharge Valve (RDV)
is open, which provides some compressor discharge gas to the
reheat condenser to further increase the reheat of the evapora-
tor air stream. (See Fig. 17 and 18.)
REHEAT CONTROL
When there is only a cooling demand, the unit will operate in
normal cooling mode. When there is only dehumidification de-
mand, the unit will operate in Dehumidification mode (Hot
Gas Reheat). When there is both cooling demand and dehu-
midification demand, the unit will operate in Dehum/Mech
Cooling mode (Subcooling). During Dehumidification and De-
hum/Mech cooling mode, the unit will run all cooling stages.
When the Outside Air Temperature is above 80°F, the Outdoor
Fans will run at maximum fan speed. When the Outside Air
Temperature is below 80°F, the Outdoor Fans will modulate to
maintain Saturated Discharge Temperature setpoint LA DE-
HUM LEV 1, LA DEHUM LEV 2 and LA DEHUM LEV,
(SETTINGS  UNIT CONFIGURATIONS  COOLING
 LOW AMBIENT). The unit can be restricted from reheat
operation by the outside temperature HUMZ LOCKOUT OAT
(SETTINGS  UNIT CONFIGURATIONS  COOLING
HUMZLOCKOUT OAT) sets the lowest outside tempera-
ture the unit is allowed to run reheat control (Default = 40°F).
22
48/50LC 04-06 VALVES
RLV Valve
Off (open)
On (closed)
On (closed)
Off (open)
Off (open)
48/50LC 07-26
OUTPUTS
LDV Valve
3-way
Off Off
Off Off
On Off
On On
On On
CLV Valve
Off (open)
Off (open)
Off (open)
On (closed)
On (closed)
VALVES
RDV Valve
2-way
Off (closed)
Off (closed)
Off (closed)
Off (closed)
On (open)