Figure 24 Co 2 Controller; Sequence Of Operation - Bard Q-TEC Q24H2D Series 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 and thus eliminating
pressure equalization noise except during defrost, are
to be used on "Auto" option, a circuit is completed for
R-W1 and R-Y on each heating "on" cycle, energizing
reversing valve solenoid and 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 make 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 coil when it is inactive. This drain does not
affect the normal operation of the system.
FIGURE 24 — CO
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
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.
CONTROLLER – FACTORY SET TO 950 PPM
2
Settings Recommended
RON
ROF
DSP
UNI
COL
COH
TOL
TOH
BAR
CAL
PRESS UP AND DOWN
ARROWS TO ENTER
CONFIGURATION MODE
USE ARROWS TO SELECT
SETTING. PUSH MIDDLE
BUTTON TO CHANGE.
CONTROLLER WILL
SHOW SET.
Default
1000 1000
950 950
C CT
US US
Not Used
Not Used
Not Used
Not Used
See Instrution with Controller
For High Altitude Installations
Used for Field Calibration
MIS-3326
Manual 2100-603
Page 33 of 44