Low Voltage Connections - Bard Q-TEC Q24H2D Series Installation Instructions Manual

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 Climate Control Option I is an electronic,
programmable thermostat with humidistat and a CO
controller. The subbase of the thermostat and CO
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 controller will energize the vent option and the
2
ID blower when the room CO
Default CO set point is 950 ppm. See Figure 24.
2
The Climate Control Option J & K are an electronic,
programmable thermostat, humidistat and CO
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
Manual 2100-603
Page 20 of 44
2
controller
2
levels rise over set level.
2
.
2
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.
Option J (Models only) the CO
will energize the vent option and the ID blower when
the room CO levels rise over set level. Default CO
2
point is 1000 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

FOR DDC CONTROL
Fan Only
Cooling Mode
Heat Pump Heating
2nd State Heating
(if employed)
Ventilation
Dehumidification
Emergency Heat
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.
"F" terminal of pin 5 of P2 is the ventilation input. This
terminal energizes any factory installed ventilation option.
NOTE: For total and proper control using DDC, a total of
7 controlled outputs are required (6 if no ventilation system
is installed). For proper system operation under Emergency
Heat conditions where the compressor needs to be deactivated,
the B-W2-E outputs need to be energized. Removing the Y
(compressor) signal alone turns the compressor off, but does
not activate the additional circuitry embedded in the heat pump
for proper and complete operation.
sensor in the controller
2
set
2
Energize G
Energize Y, G
Energize Y, G, B
Energize G, W2, Y, B
Energize G, O1
Energize 4
Energize B, W2, E, G