Bard WGCRVS-3C, Installation Instructions Manual

Page: 9 / 17

Manual 2100-757B
Page 9 of 17
Ventilator Checkout
Blade Adjustment for Desired Ventilator Air
The amount of ventilation air supplied by the
commercial room ventilator is dependent on four
factors.
a. Return air duct static pressure drop
b. Supply air duct static pressure drop
c. Indoor blower motor speed
d. Damper blade open position setting
To determine the amount of fresh air that will be
supplied to the structure, first determine the pressure
drops of the supply and return air ducts. For free blow
application with return air filter grille and supply grille,
assume .05 supply static and .10 return static.
Determine on what speed the evaporator motor is
running.
Refer to the graphs found on pages 12-14 to
determine the blade setting necessary to achieve the
ventilation air required at the supply and return static
duct pressure drops that are applicable.
NOTE:
The ventilation air shown in the graphs on pages
12-14 is without the condenser fan running.
When the condenser fan is running, the
ventilation air will increase slightly.
WGCRVS Model Checkout
1. Open blower door and remove filters to gain
access to the CRV control board (8201-167)
located behind the front fill partition on top of the
ventilator.
2. Resupply power to unit.
3. Energize the evaporator blower by switching
thermostat to the manual fan position with heat/
cool in OFF position.
4. Ventilator should open to the position set by the
OCC potentiometer on the CRV control board (see
Figure 6 on page 10). Cycle OCC potentiometer
to full open through full close. Observe damper
blade operation throughout travel to assure free,
unobstructed movement.
5. Adjust OCC potentiometer until desired blade
setting is reached with power applied to unit. See
the graphs found on pages 12-14 for required
blade setting versus ventilator air for the unit
installed.
6. De-energize the evaporator blower. Damper blade
should close.
7. Re-install filter.
WGCRVS Sequence of Operation
This ventilation option includes a control board with
blade positioning potentiometers along with an input
for a 2-10V input signal (see Figure 6 on page 10).
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.
“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 or demand.
“Y1” Potentiometer setting:
Not applicable on this
model.
“Y2” Potentiometer setting:
Not applicable on this
model.
Pre-Purge Feature
Pre-purge is used to ventilate a specified CFM amount
before occupants enter the room or structure. The
control board has a built-in pre-purge timer that can
be set to 30, 60 and 90 minute intervals by moving
the jumper (see Figure 6 on page 10). This timer will
start when the jumper is installed and the A terminal
is energized on the low voltage terminal strip. Blade
adjustment can be made on the PP potentiometer.
Once the timer has timed out, the board will default
to the occupied setting and this blade position can
be adjusted on the OCC potentiometer. If the timer is
set to 0 (off—shipped position), the occupied setting
is instantaneous and the pre-purge setting (PP) is no
longer in the sequence.
Occupied Setting
Occupied is used to ventilate a specified CFM amount
when occupants enter the room or structure. The
control board will energize the occupied setting
after the pre-purge cycle, or if pre-purge is disabled
immediately when the A terminal is energized on the
low voltage strip. Blade adjustment can be made on the
OCC potentiometer.
Y1 Setting
Not applicable on this model
Y2 Setting
Not applicable on this model
2-10V Operation
A CO
2
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 CO
2
sensor part #8403-096 can
be used when the 2-10V output is connected to