Figure 24 Co 2 Controller; Sequence Of Operation - Bard Q-TEC Q24H3DA Installation Instructions Manual

SEQUENCE OF OPERATION

Cooling – Circuit R-Y makes the thermostat pull in
the compressor contactor starting the compressor
and outdoor motor. The G (indoor motor) circuit
is automatically completed on any call for cooling
operation, or can be energized by manual fan switch on
subbase for constant air circulation.
Heating – A 24V solenoid coil on the reversing valve
controls heating cycle operation. Two thermostat
options, one allowing "Auto" change over from cycle
to cycle and the other constantly energizing solenoid
coil during heating season (thus eliminating pressure
equalization noise except during defrost), are available
and dependent on the thermostat used.
The first option uses an "Auto" option. A circuit is
completed for R-W1 and R-Y on each heating "on"
cycle, pulling in compressor contactor, starting
compressor and outdoor motor. R-G also makes,
starting indoor blower motor. Heat pump heating cycle
now in operation.
The second option has no "Auto" change over position,
but instead energizes the reversing valve solenoid
constantly whenever the system switch on subbase
is placed in "Heat" position, the "B" terminal being
constantly energized from R. A thermostat demand
for heat completes R-Y circuit, pulling in compressor
contactor, starting compressor and outdoor motor. R-G
also makes, starting indoor blower motor.
Reheat Circuit – There is a small capillary tube inserted
between the reheat coil return line and suction line
that will prevent liquid from accumulating in the reheat
NOTE: MENU
JUMPER MUST
BE SET TO "ON"
TO CHANGE ANY
SETTINGS WITH
THE FRONT BUTTONS.
TO LOCK THE CO2
CONTROLLER MOVE
JUMPER TO "OFF" AFTER
IT HAS BEEN CONFIGURED
FIGURE 24 – CO Controller (Factory set to 950 ppm)
2
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 25
and 26 for the location of the check valve and drain
back capillary.
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 brings on stage one electric
heat to maintain 65°.
High/Low Pressure Control provides protection for the
compressor. In the event system pressures go above
600 PSI or below 15 PSI in either cooling or heating
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.
The bypass timer should be set to 120 seconds. This
is to assure there is no nuisance tripping of the low-
pressure control during startup in heating mode under
cold weather conditions.
PRESS UP AND DOWN
ARROWS TO ENTER
CONFIGURATION MODE
USE ARROWS TO SELECT
SETTING. PUSH MIDDLE
BUTTON TO CHANGE.
CONTROLLER WILL
SHOW SET.
Settings Recommended Default
RON 1000 1000
ROF 950 950
DSP C CT
UNI US US
COL Not Used
COH Not Used
TOL Not Used
TOH Not Used
See Instrution with Controller
BAR
For High Altitude Installations
CAL Used for Field Calibration
MIS-3326
Manual 2100-653
Page 33 of 44