Bard 920-0074 qwserv manual Recommended Control Sequences, Ventilation Airflow, Control Wiring

RECOMMENDED CONTROL

SEQUENCES

Several possible control scenarios are listed below:

1.Use a programmable electronic thermostat with auxiliary terminal to control the ERV based on daily programmed occupancy periods. Bard markets and recommends Bard Part No. 8403-060 programmable electronic thermostat for heat pump applications.

2.Use a motion sensor in conjunction with a mechanical thermostat to determine occupancy in the classroom. Bard markets the CS2000A for this use.

3.Use a DDC control system to control the ERV based on a room occupancy schedule.

4.Tie the operation of the ERV into the light switch. The lights in a room are usually on only when occupied.

5.Use a manual timer that the occupants turn to energize the ERV for a specific number of hours.

6.Use a programmable mechanical timer to energize the ERV and indoor blower during occupied periods of the day.

7.Use Bard Part No. 8403-056 CO2 controller for “on- demand” ventilation.

CONTROL WIRING

The QWSERV comes wired in the low voltage control circuit from the factory.

With the “X” Remote Thermostat Option, it is default wired into the “A” terminal, which drives the vent to operate only during occupied periods when using a Bard 8403-060 thermostat or Bard CS2000 controller. If you prefer for the QWSERV to operate anytime the blower is operational, you will need to install a jumper wire from “G” to “A”. If you prefer to use Bard 8403-056 CO2 controller to make the ventilation “on-demand”, there is a connection adjacent to the thermostat connections in the unit upper right-hand corner, and is marked to match CO2 controller connections. Furthermore, disconnect and tape off the wire as shown in Figure 4 and you will need to field set the CO2 sensor jumpers per Figure 5.

With the “D” Door Mounted Thermostat Option, the thermostat is already connected and programmed to operate the QWSERV only during occupied periods.

With the “H” Door Mounted Thermostat and CO2 controller, the unit is ready to go with “on-demand” ventilation as controlled by the CO2 controller.

VENTILATION AIRFLOW

The ERV is equipped with a 3-speed motor to provide the capability of adjusting the ventilation rates to the requirements of the specific application by simply changing motor speeds.

TABLE 1

VENTILATION AIR (CFM)

	High Speed	Medium Speed	Low Speed
	(Black)	(Blue)	(Red)
CFM
	450	375	300

The ERV units are wired from the factory on medium intake and low exhaust speeds. The ERV is equipped with independently controlled 3-speed motor to provide the capability of adjusting the ventilation rates to the requirements of the specific application and to be able to provide positive pressure in the structure. This is accomplished by setting the intake blower on a higher speed than the exhaust blower.

WARNING

Open disconnect to shut all power OFF before doing this. Failure to do so could result in injury or death due to electrical shock.

Moving the speed taps located in the control panel can change the blower speed of the intake and exhaust. See Figure 1.

FIGURE 1

BLOWER SPEED ADJUSTMENT

Manual	2100-533A
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