Bard QWSCRV is a commercial room ventilator that provides fresh air to meet indoor air quality standards. It automatically adjusts to maintain consistent fresh air intake levels in different modes of operation, including blower only, part load cooling, and full load cooling. The damper position for each mode can be set using potentiometers on the CRV control board. It also features a 2-10V input for modulating control, allowing for integration with CO2 sensors or other devices for demand-controlled ventilation.
Bard QWSCRV is a commercial room ventilator that provides fresh air to meet indoor air quality standards. It automatically adjusts to maintain consistent fresh air intake levels in different modes of operation, including blower only, part load cooling, and full load cooling. The damper position for each mode can be set using potentiometers on the CRV control board. It also features a 2-10V input for modulating control, allowing for integration with CO2 sensors or other devices for demand-controlled ventilation.
Page 1 of 10
INSTALLATION INSTRUCTIONS
Bard Manufacturing Company, Inc.
Bryan, Ohio 43506
www.bardhvac.com
Manual: 2100-763
Supersedes: NEW
Date: 1-19-22
Commercial Room Ventilator
with Exhaust, Multi-Step and
Optional CO2/2-10V Modulating Control
For Use with Bard QW*S Series Geothermal
2-Stage Heat Pumps
Model: QWSCRV (920-0538)
Manual 2100-763
Page 2 of 10
CONTENTS
Description .............................................................3
Blade Adjustment for Desired Ventilation Air ..............4
"V" Option CRV Sequence of Operation ......................7
Figures
Figure 1 CRV Installation and Adjustment ............3
Figure 2 CRV Control Board ................................7
Figure 3 8403-096 CO2 Sensor Set Up ................ 9
Figure 4 CRV Wiring Diagram ............................ 10
Table
Table 1 Factory Default Settings.........................4
Graphs
Graph 1 QW2S Air Flow vs. Damper Position ........ 5
Graph 2 QW3S Air Flow vs. Damper Position ........ 5
Graph 3 QW4S Air Flow vs. Damper Position ........ 6
Graph 4 QW5S Air Flow vs. Damper Position ........ 6
Manual 2100-763
Page 3 of 10
Description
The QWSCRV ventilator is designed to be used with
Bard QW*S Q-TECTM series 2-stage geothermal
heat pumps. It is an electromechanical vent system
designed to provide fresh air to meet indoor air quality
standards. It automatically adjusts to the mode of
operation to maintain consistent fresh air intake
levels. Examples are blower only, part load cooling and
full load cooling, which are all set for different total
airows. Ventilator is spring-return and will return to
the closed position upon loss of power.
FIGURE 1
CRV Installation and Adjustment
MIS-4360 A
CRV MOUNTING HOLES
USE POTENTIOMETERS ON
CRV BOARD TO ADJUST
THE BLADE POSITION IN
EACH MODE OF OPERATION
Manual 2100-763
Page 4 of 10
Blade Adjustment for Desired
Ventilator Air
The amount of ventilation air supplied by the
commercial room ventilator is dependent on ve (5)
factors:
1. Return air pressure drop.
2. Supply air duct static pressure drop.
3. Indoor blower motor speed.
4. Damper blade open position setting for each mode
of operation.
5. Tightness or looseness of building envelope.
The damper position for each mode of operation must
be set using the setpoint potentiometers on the CRV
control board (see Figure 2 on page 7). Refer to Table 1
for factory default settings.
Refer to the graphs on pages 5 and 6 to determine the
necessary blade setting to achieve the ventilation air
required based upon blower only, part load or full load
modes of operation. The graphs are model specic, so
be sure to match the graph to the appropriate model.
1. Set the damper position for blower only operation.
A. Energize the evaporator blower by switching
the thermostat to the manual fan position with
heat/cool in OFF position (or jumper R to G
with thermostat disconnected at unit).
B. Locate potentiometer OCC on the CRV control
board (see Figure 2).
C. Using a small screwdriver, adjust
potentiometer OCC until damper position
aligns with numerical location on the label
interior of the sheet metal damper assembly
per the graph.
2. Set the damper position for part load (stage 1)
cooling or heating operation.
A. Energize the evaporator blower and compressor
by switching thermostat to heat or cool mode
and setting it to a minimum offset to the room
temperature to engage the mode of operation
desired (or jumper R to G and R to Y1 [+ O for
cooling] with thermostat disconnected at unit).
B. Locate potentiometer Y1 on the CRV control
board (see Figure 2).
C. Using a small screwdriver, adjust
potentiometer Y1 until damper position aligns
with numerical location on the label interior
of the sheet metal damper assembly per the
graph.
3. Set the damper position for full load (stage 2)
cooling or heating operation.
A. Energize the evaporator blower and compressor
by switching thermostat to heat or cool mode
and setting it to a minimum offset to the room
temperature to engage the mode of operation
desired (or jumper R to G, R to Y1 and R to Y2
[+ O for cooling] with thermostat disconnected
at unit).
B. Locate potentiometer Y2 on the CRV control
board (see Figure 2).
C. Using a small screwdriver, adjust
potentiometer Y2 until damper position aligns
with numerical location on the label interior
of the sheet metal damper assembly per the
graph.
TABLE 1
Factory Default Settings
Mode of
Operation Potentiometer
QW2S QW3S QW4S QW5S
Blade
Setting
Approx.
CFM
Blade
Setting
Approx.
CFM
Blade
Setting
Approx.
CFM
Blade
Setting
Approx.
CFM
Vent
(Blower Only) R1 17 150 17 150 17 200 17 225
Part Load
(Stage 1) R2 15 150 15 150 15 200 15 250
Full Load
(Stage 2) R3 13 150 13 150 13 200 13 225
Manual 2100-763
Page 5 of 10
GRAPH 2
QW3S CRV Airow vs. Damper Position
GRAPH 1
QW2S CRV Airow vs. Damper Position
0
50
100
150
200
250
300
350
400
450
510 15 20 25 30
FRESH AIR CFM
DAMPER POSITION
QW2S CRV AIRFLOW VS. DAMPER POSITION
Full Load
Part Load
Blower Only
0
50
100
150
200
250
300
350
400
450
500
550
510 15 20 25 30
FRESH AIR CFM
DAMPER POSITION
QW3S CRV AIRFLOW VS. DAMPER POSITION
Rated Full Load
Optional Full Load
Part Load
Blower Only
Manual 2100-763
Page 6 of 10
GRAPH 4
QW5S CRV Airow vs. Damper Position
GRAPH 3
QW4S CRV Airow vs. Damper Position
0
50
100
150
200
250
300
350
400
450
500
550
600
510 15 20 25 30
FRESH AIR CFM
DAMPER POSITION
QW4S CRV AIRFLOW VS. DAMPER POSITION
Full Load
Optional Full Load
Part Load
Blower Only
0
50
100
150
200
250
300
350
400
450
500
550
600
650
510 15 20 25 30
FRESH AIR CFM
DAMPER POSITION
QW5S CRV AIRFLOW VS. DAMPER POSITION
Full Load
Optional Full Load
Part Load
Blower Only
Manual 2100-763
Page 7 of 10
"V" Option CRV Sequence of Operation
The “V” Ventilation option includes a control board with
blade positioning potentiometers along with an input
for a 2-10V input signal (see Figure 2).
Adjustable potentiometers:
“PP” Potentiometer setting: This potentiometer can be
used to adjust the blade setting for outdoor air intake
during a pre-purge cycle. The pre-purge cycle time
is based on the setting of the pre-purge timer. The
pre-purge time can be set to 0, 30, 60 or 90 minutes
using the PP jumper on the CRV control board. The
pre-purge function is triggered when the "A" terminal on
the low voltage terminal strip is energized, indicating
occupancy. Once the selected time has passed, the
blade will move to the position set by the "OCC"
potentiometer.
“OCC” Potentiometer setting: This potentiometer can
be used to adjust the blade setting for outdoor air
intake when the “A” terminal is energized on the low
voltage terminal strip indicating occupancy.
FIGURE 2
CRV Control Board
“Y1” Potentiometer setting: This potentiometer can be
used to adjust the blade setting for outdoor air intake
when the “Y1” terminal is energized on the low voltage
terminal strip indicating 1st stage cooling or Balanced
Climate operation. When energized, it overrides the
“OCC” potentiometer setting.
“Y2” Potentiometer setting: This potentiometer can be
used to adjust the blade setting for outdoor air intake
when the “Y2” terminal is energized on the low voltage
terminal strip indicating 2nd stage cooling operation.
When energized, it overrides the “OCC” and “Y1”
potentiometer settings.
2-10V Operation
A CO2 sensor or other device sending a 2-10V signal
can be used to control the damper motor. Two control
methods are available to control the damper motor:
• Method 1: The control board will accept a
2-10VDC signal with a resistive load greater than
5000 ohms. Bard CO2 sensor part #8403-096
can be used when the 2-10V output is connected
to the gray wire in position 9 on the 12-pin vent
MIS-4362 A
WHEN Y2 IS ENERGIZED
Y1 WILL OVERRIDE OCC
30
SETTING FOR 2ND STAGE
60
90
TURN OFF FOR C02
COOLING OR BLADE POSITION
FULL MODULATION
PRE-PURGE
TIMER
POT "Y1" SETTING FOR
STAGE ONE COOLING
POT "OCC" OCCUPIED SETTING
POT "PP" PRE-PURGE
SET FOR PREOCCUPANCY
0
Manual 2100-763
Page 8 of 10
plug in the unit control panel. All potentiometers
must be set to the off position and the PP jumper
must be in the "0" position for total modulation.
The OCC potentiometer can be used to maintain
a minimum blade position when "A" is energized.
Refer to Figure 3 for more information on Bard CO2
sensor part #8403-096 set up.
• Method 2: The damper motor will accept a
2-10VDC signal with a resistive load less than
5000 ohms. This method involves bypassing the
control board and powering the motor directly from
the device providing the 2-10VDC modulating
signal. The gray wire on the vent control harness
(2-10V IN on control board) must be spliced with
the white wire ran to the damper motor (2-10V
OUT on control board). The 2-10VDC signal can
be connected to the gray wire in position 9 on the
12-pin vent plug in the unit control panel.
NOTE: For proper setup of a generic field-installed CO2
sensor, refer to the manufacturer's installation
instructions. Bard recommends setting the
control for a 700-1500 ppm CO2 control band;
local standards may vary.
During 2-10VDC operation with A energized and pre-
purge timed operation active, DC voltage signaling
occupancy from a source such as a CO2 sensor will
increase ventilation amounts as needed.
Manual 2100-763
Page 9 of 10
FIGURE 3
8403-096 CO2 Sensor Set Up
ON
OFFOFFOFF
ON
4 65
23
ON
1
PRESS UP AND DOWN
ARROWS TO ENTER
CONFIGURATION MODE
USE ARROWS TO SELECT
SETTING. PUSH MIDDLE
BUTTON TO CHANGE.
CONTROLLER WILL
SHOW SET.
IT HAS BEEN CONFIGURED.
DIP SWITCH TO "OFF" AFTER
CONTROLLER MOVE
NOTE: MENU
DIP SWITCH MUST
BE IN "ON" POSITION #5
TO CHANGE ANY
SETTINGS WITH
THE SIDE BUTTONS.
TO LOCK THE CO2
DIP SWITCHES MUST BE
POSITIONED AS SHOWN
FOR PROPER OPERATION MIS-4025 C
Settings Recommended Default
RON
(RELAY ON SET POINT) 725
ROF
(RELAY OFF SET POINT) 700
DSP
(DISPLAY
CONFIGURATION) C CT
UNI
(UNITS SELECTION) US US
COL
(CO2 LOW OUTPUT
RANGE) 700 0
COH
(CO2 HIGH OUTPUT
RANGE) 1500 2000
TOL
(TEMP. LOW OUTPUT
RANGE) Not Used
TOH
(TEMP. HIGH OUTPUT
RANGE) Not Used
BAR
(BAROMETRIC
PRESSURE)
See Instructions with
Controller For High
Altitude Installations
CAL
(CALIBRATION) Used for Field Calibration
Manual 2100-763
Page 10 of 10
FIGURE 4
CRV Wiring Diagram
UNIT LOW -VOLT
90
60
30
0
BROWN/WHITE
*A
TERMINAL STRIP RCA
*B
*B
CO2
(8403-096)
3
24
VENT PLUG
RED
WHITE
BLACK
BROWN
*Unused - Tape off
3
CRV CONTROL BOARD
YELLOW
PURPLE
BLACK/WHITE
BLACK/WHITE
BROWN/WHITE
BLUE
RED/WHITE
BLUE
RELAY
2
GRAY
RED/WHITE
BROWN/WHITE
PURPLE
22
26
9
NC
NO
1211108
ACTUATOR
25
COM
24V
Control
FDBK
6
5
4
3
2
4114-107 A
2
1
1 4 5 6 7
1
COM
-
1
-
2
-
3
-
4
-
5
-
6
-
7
-
8
-
9
-
10
Bard QWSCRV is a commercial room ventilator that provides fresh air to meet indoor air quality standards. It automatically adjusts to maintain consistent fresh air intake levels in different modes of operation, including blower only, part load cooling, and full load cooling. The damper position for each mode can be set using potentiometers on the CRV control board. It also features a 2-10V input for modulating control, allowing for integration with CO2 sensors or other devices for demand-controlled ventilation.
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