Bard 920-0074 User Manual

OPERATION INSTRUCTIONS

ENERGY RECOVERY VENTILATOR

WITH EXHAUST

Model:

For Use With Bard

2 Through 5 Ton

920-0074
QWSERV

QW*S Series

Bard Manufacturing Company, Inc.
Bryan, Ohio 43506

Since 1914...Moving ahead, just as planned.

Manual: 2100-533A
Supersedes: 2100-533
File: Volume II, Tab 14
Date: 12-08-10

Manual 2100-533A
Page 1 of 12

CONTENTS

Electrical Specifications .......................................... 3

General Description of ERV ................................... 3

Control Requirements ............................................ 3

Recommended Control Sequences ....................... 4

Control Wiring ........................................................ 4

Ventilation Airflow ................................................... 4

Performance & Application Data ............................ 5

Energy Recovery Ventilator Maintenance ........6 & 7

Maintenance Procedures ....................................... 7

Figures

Figure 1 Blower Speed Adjustment ....................... 4

Figure 2 Belt Replacement .................................... 8

Figure 3 Hub Assembly with Ball Bearings ............ 9

Figure 4 Disconnect & Tape Off Wiring ................ 11

Figure 5 Field Set CO

Wiring Diagram

.............................................................. 10

Tables

Table 1 Ventilation Air (CFM)................................ 4

Table 2 Summer Cooling Performance ................ 5

Table 3 Winter Heating Performance ................... 6

Sensor Jumpers .............. 12

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Manual 2100-533A
Page 2 of 12

COPYRIGHT DECEMBER 2009

BARD MANUFACTURING COMPANY, INC.

BRYAN, OHIO USA 43506

ELECTRICAL SPECIFICATIONS

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GENERAL DESCRIPTION

The Energy Recovery Ventilator was designed to
provide energy efficient, cost effective ventilation to
meet I. A. Q. (Indoor Air Quality) requirements while
still maintaining good indoor comfort and humidity
control for a variety of applications such as schools,
classrooms, lounges, conference rooms, beauty salons
and others. It provides a constant supply of fresh air for
control of airborne pollutants including CO2, smoke,
radon, formaldehyde, excess moisture, virus and
bacteria.

The ventilator incorporates patented rotary heat
exchange state-of-the-art technology to remove both
heat & moisture and provides required ventilation to
meet the requirements of ASHRAE 62.1 standard.

It is designed as a single package which is factory
installed. The package consists of a unique rotary
Energy Recovery Cassette that can be easily removed
for cleaning or maintenance. It has two 15-inch
diameter heat transfer wheels for efficient heat transfer.
The heat transfer wheels use a permanently bonded dry
desiccant coating for total heat recovery.

Ventilation is accomplished with 2 blower/motor
assemblies each consisting of a drive motor and dual
blowers for maximum ventilation at low sound levels.
Motor speeds can be adjusted so that air is exhausted at
the same rate that fresh air is brought into the structure
thus not pressuring the building. The rotating energy
wheels provide the heat transfer effectively during both
summer and winter conditions.

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CONTROL REQUIREMENTS

1. Indoor blower motor must be run whenever the ERV
is run.

2. Select the correct motor speed on the ERV. Using
Table 1 of the ERV Installation Instructions
determine the motor speed needed to get the desired
amount of ventilation air needed. For instance, do
not use the high speed tap on a ERV if only 200
CFM of ventilation air is needed. Use the low speed
tap. Using the high speed tap would serve no useful
purpose and would effect the overall efficiency of the
air conditioning system. System operation costs
would also increase.

3. Run the ERV only during periods when the
conditioned space is occupied. Running the ERV
during unoccupied periods wastes energy, decreases
the expected life of the ERV, and can result in a large
moisture buildup in the structure. The ERV can
remove up to 60 to 70% of the moisture in the
incoming air, not 100% of it. Running the ERV
when the structure is unoccupied allows moisture to
build up in the structure because there is little or no
cooling load. Thus, the air conditioner is not running
enough to remove the excess moisture being brought
in. Use a control system that in some way can
control the system based on occupancy.

NOTE: The Energy Recovery Ventilator is NOT a

dehumidifier.

NOTE: Operation is not recommended below 5°F

outdoor temperature because freezing of
moisture in the heat transfer wheel can occur.

IMPORTANT

Operating the ERV during unoccupied periods
can result in a build up of moisture in the
classroom.

Manual 2100-533A
Page 3 of 12

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.

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)

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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.

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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 “on­demand” 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.

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

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 CO
controller, the unit is ready to go with “on-demand”
ventilation as controlled by the CO2 controller.

Manual 2100-533A
Page 4 of 12

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