Eev Operation; Eev Superheat Control; Additional Eev Alarms; Low Superheat Alarm - Bard MEGA-TEC W090A Service Instructions Manual

FIGURE 22
Adjusting Evaporator Freeze Sensor Values

EEV Operation

EEV Superheat Control

The electronic expansion valve (EEV) will open or
close to maintain the superheat setpoint while the
compressor is running (see Table 4). When the
compressor is not running, the valve will close to the
20% open default position.
TABLE 4
Unit Specific Superheat Setpoints
Unit
W090A
W120A
W150A
Low superheat protection will be active once the
superheat value is at or below 5°F. At this point,
the control will aggressively close the valve so that
superheat is maintained.

Additional EEV Alarms

Low Superheat Alarm

This alarm will become active when the calculated
superheat goes below 5°F. This alarm will clear itself
when the condition is no longer present.
This alarm cannot be adjusted.

Indoor Airflow

Indoor Airflow Components

Blower

The unit is equipped with a blower that is driven by an
electronically commutated motor (ECM). The blower
is controlled by a 0-100% signal through Modbus
communication. The motor controller converts this
signal to a PWM signal. The blower uses a 22" (560
mm) diameter wheel and operates up to 1500 rpm.
The blower output can be put into an override mode for
verification or troubleshooting.
Manual 2100-671C
Page 18 of 59
Superheat
14°F
10°F
14°F
To put the blower into override:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
TECHNICIAN password 1313.
3. Press UP or DOWN keys to scroll to I/O Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Fans / Blowers;
press ENTER key.
5. Press UP or DOWN keys to scroll to Blower 1.
6. Press ENTER key to scroll to Blower Overrides?
(see Figure 23).
7. Press UP or DOWN key to change No to Go. The
override will begin and the screen will change to
the override screen (see Figure 23).
The override will last for 5 minutes or until the Blower
Overrides parameter is set to No again.
FIGURE 23
Putting Blower Output into Override Mode
TABLE 5
Rated Airflow
Nominal Rated CFM
High
W090A 3000
W120A 4000
W150A 4600
Nominal Rated ESP
Low
2100 0.25
2800 0.30
2800 0.35