20
Dehumidification (Hot Gas Reheat Mode)
This mode provides maximum latent cooling with little to no
sensible capacity. This mode can operate to provide
dehumidification when there is no cooling demand. For
48/50LC07--26 the 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. (See
Fig. 18.) For 48/50LC04--06 units, The refrigerants flows from the
outdoor condenser, through the de--energized RLV and through the
reheat condenser coil to the expansion device. The Cooling Lquid
Valv e (CLV) is closed. For 48/50LC04--2 6 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 evaporator air stream. (See Fig. 17.)
Reheat Control
When there is only a cooling demand, the unit will operate in
normal cooling mode. When there is only dehumidification
demand, the unit will operate in Dehumidification mode (Hot Gas
Reheat). When there is both cooling demand and dehumidification
demand, the unit will operate in Dehum/Mech Cooling mode
(Subcooling). During Dehumidification and Dehum/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 DEHUM LEV 1, LA DEHUM LEV 2
and LA DEHUM LEV, (SETTINGSUNIT
CONFIGURATIONSCOOLINGLOW AMBIENT. The unit
can be restricted from reheat operation by the outside temperature
HUMZ LOCKOUT OAT (SETTINGSUNIT
CONFIGURATIONS > COOLINGHUMZLOCKOUT OAT)
sets the lowest outside temperature the unit is allowed to run reheat
control (Default = 40_F).
HUMIDI-MIZER COIL
COMPRESSOR
OUTDOOR AIR
INDOOR SUPPLY
AIR
INDOOR RETURN
AIR
RLV
VALVE
EXPANSION
VALVE
(TXV)
= CLOSED VALVE
= OPEN VALVE
RDV
VALVE
EVAPORATOR COIL
CONDENSER COIL
CLV
VALVE
C14121
Fig. 13 -- Normal Cooling Mode – Humidi--MiZer System 48/50LC 04 -- 06
HUMIDI-MIZER COIL
COMPRESSOR
OUTDOOR AIR
INDOOR SUPPLY
AIR
INDOOR RETURN
AIR
3-WAY
VALVE
EXPANSION
VALVE
(TXV)
= CLOSED VALVE
= OPEN VALVE
= 3-WAY VALVE
RDV
VALVE
EVAPORATOR COIL
CONDENSER COIL
C14114
Fig. 14 -- Normal Cooling Mode – Humidi--MiZer System 48/50LC 07 -- 26
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