Manual 2100-653A
Page
20 of 44
the electric heaters will turn off and the airflow will be
reduced and the system will continue to dehumidify until
humidistat is satisfied.
If the unit is running in heat pump mode and the
humidistat calls for dehumidification, the
dehumidification mode takes precedence over the heat
pump heating mode. The unit will not return to the
heating mode until 2nd stage heating is called for.
Climate control
Option I
is an electronic, programmable
thermostat with humidistat and a CO
2
controller. The
subbase of the thermostat and CO
2
controller are factory
wired to the front panel of the unit. See Figure 20 for
wiring diagram. This unit has a refrigerant reheat circuit
that is controlled by a 3 way valve.
When the humidity is above the setpoint of the
humidistat, the compressor circuit and the 3 way valve
are energized and the evaporator airflow is reduced. The
3 way valve directs hot discharge gas into a separate
desuperheating condenser circuit that reheats the
conditioned air before it is delivered to the room. When
the humidistat is satisfied, the system switches back to
normal air conditioning mode.
If the thermostat calls for cooling during dehumidification
mode, the call for cooling takes precedence over the
dehumidification and the unit will cool until the thermostat
is satisfied. Once the call for cooling is satisfied, the unit
may continue to dehumidify.
If the thermostat calls for heat when the unit is in the
dehumidification mode, the electric heaters will energize and
the evaporator airflow will return to the heating airflow. When
the thermostat is satisfied, the electric heaters will turn off
and the airflow will be reduced and the system will continue
to dehumidify until humidistat is satisfied.
If the unit is running in heat pump mode and the
humidistat calls for dehumidification, the
dehumidification mode takes precedence over the heat
pump heating mode. The unit will not return to the
heating mode until 2nd stage heating is called for.
The CO
2
controller will energize the vent option and the
ID blower when the room CO
2
levels rise over set level.
Default CO
2
setpoint is 950 ppm. See Figure 24.
Climate control
Options J & K
are an electronic,
programmable thermostat, humidistat and CO
2
controller
"J" model only
) with BACnet, MS/TP or Ethernet
connections.
When the humidity is above the setpoint of the humidistat,
the compressor circuit and the 3-way valve are energized
and the evaporator airflow is reduced. The 3-way valve
directs hot discharge gas into a separate desuperheating
condenser circuit that reheats the conditioned air before it is
delivered to the room. When the humidistat is satisfied, the
system switches back to normal air conditioning mode.
If the thermostat calls for cooling during dehumidification
mode, the call for cooling takes precedence over the
dehumidification and the unit will cool until the thermostat
is satisfied. Once the call for cooling is satisfied, the unit
may continue to dehumidify.
If the thermostat calls for heat when the unit is in the
dehumidification mode, the electric heaters will energize
and the evaporator airflow will return to the heating airflow.
When the thermostat is satisfied, the electric heaters will
turn off and the airflow will be reduced and the system will
continue to dehumidify until humidistat is satisfied.
If the unit is running in heat pump mode and the
humidstat calls for dehumidification, the dehumidification
mode takes precedence over the heat pump heating mode.
The unit will not return to the heating mode until 2nd
stage heating is called for.
On Option J Models only
, the CO
2
sensor in the controller
will energize the vent option and the ID blower when the
room CO
2
levels rise over set level. Default CO
2
setpoint is
950 ppm.
NOTE:
On Option X, field-provided means to control
ventilation must be used if any of the motorized
ventilation options are installed.
LOW VOLTAGE CONNECTIONS
These units use a grounded 24 volt AC low voltage circuit.
The
“R”
terminal is the
hot
terminal and the
“C”
terminal
is
grounded.
“G”
terminal or pin 6 of P2 is the
fan input
. If the climate
control option is abandoned and connections are made
directly to P2 pin 6 of P2 must be energized for proper
operation.
“Y1”
terminal or pin 7 of P2 is the
compressor input
.
“W1”
terminal or pin 8 of P2 is the
fist stage heat.
“R”
terminal or pin 10 of P2 is
24 VAC hot
.
“C”
terminal or pin 11 of P2 is
24 VAC grounded.
Terminal
“1”
or pin 4 of P2 is the dehumidification circuit.
Terminal
“2”
or pin 12 of P2 is the dehumidification
circuit. A contact must connect terminals 1 and 2.
“W2”
terminal or pin 9 of P2 is
second stage heat
(if
equipped). If the unit is equipped with an optional
hot water coil plenum box or electric heat these will be
energized by this terminal.
LOW VOLTAGE CONNECTIONS
FOR DDC CONTROL
Fan Only
Energize G
Cooling Mode
Energize Y, G
Heat Pump Heating
Energize Y, G, B
2nd State Heating
Energize G, W2, Y, B
(if employed)
Ventilation
Energize G, O1
Dehumidification
Energize 4
Emergency Heat
Energize B, W2, E, G
