Bard QW242D Installation Instructions Manual - page 26
Manual 2100-418F
Page
26 of 49
Reheat Circuit – There is a small orifice inserted
between the reheat coil return line and suction line that
will prevent liquid from accumulating in the reheat coil
when it is inactive. This drain does not affect the
normal operation of the system.
There is a check valve located in the reheat coil return
line. It has a soft spring to hold the ball on the seat.
This will make the method of checking the ball freedom
with a magnet difficult. Refer to Figures 19 and 20 for
the location of the check valve and orifice.
When the system is operating in the dehumidification
mode the suction pressure will be reduced by 4 to 8 psig
and the discharge pressure will be reduced by 19 to 22
psig.
Return Air Thermostat – In dehumidification mode, if
the return air temperature is lower than 65°, the return
air thermostat closes and deactivates dehumidification.
High / Low Pressure Control provides protection for
the compressor. In the event system pressures go high
or low pressure settings in either heating or cooling
mode the compressor will be stopped. This will activate
the red light located in the control panel. The lockout
circuit will hold compressor off line. When the system
problem is corrected, the unit operation can be restored
by turning of the main power supply off and then back
on, or reset the room thermostat. The low pressure
control has a bypass to eliminate nuisance lockout on
cold start up.
OPTIONAL CLIMATE CONTROLS
SEQUENCE OF OPERATION
The Climate Control Option E is an electronic
programmable thermostat and humidistat. This unit has
a refrigerant reheat circuit that is controlled by a three
way valve.
When the humidity is above the setpoint of the
humidistat, the compressor circuit and the three way
valve are energized and the evaporator airflow is
reduced. The three 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 call 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 first stage heat when the unit
is in dehumidification mode, the unit will continue to
run in dehumidification mode until a second stage heat
call is received.
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 second stage heating is called for.
The climate Control Option F has a non-programmable
electronic thermostat, timer and humidistat. This unit
has a refrigerant reheat circuit that is controlled by a
three way valve.
Unit operation is controlled by the manually operated
timer. Normal heating, cooling or ventilation is
available only when the timer is on. Dehumidification
can be set to be available only when the timer is on, or
to be available continuously by switching a jumper on
the relay logic board.
When the humidity is above the setpoint of the
humidistat, the compressor circuit and the three way
valve are energized and the evaporator airflow is
reduced. The three way valve directs hot discharge gas
into a separate desuperheating condenser circuit that
reheats the conditioned air before it is delivered to the
room. If the return air thermostat senses a temperature
below 65° during dehumidification is cancelled. 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 first stage heat when the unit
is in dehumidification mode, the unit will continue to
run in dehumidification mode until a second stage heat
call is received.
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 second stage heating is called for.
The Climate Control Option G has a non-programmable
electronic thermostat, humidistat and is compatible for
use with a CS2000A1 Energy Control Monitor. This
unit has a refrigerant reheat circuit that is controlled by
a three way valve.
Unit operation is controlled by the thermostat and
humidistat and optional CS2000A1 Energy Monitor
Controller can be easily integrated by simple connection
to the low voltage terminal block provided. See Figure
17.