Emergency Ventilation Mode; Electric Heat Option; Electric Heat Components; Electric Heating Element - Bard MEGA-TEC W090A Service Instructions Manual

5. Press ENTER key to scroll to Use emergency cool
in Orphan Mode? (see Figure 47).
6. Press UP or DOWN keys to change the value.
FIGURE 47
Emergency Cool – Orphan Mode
When this feature is used instead of using the zone
sensor, an alarm will be triggered by the high return air
temperature alarm.
To adjust the return air temperature settings:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to System Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Return Air
Alarm A5.
5. Press ENTER key to scroll to Enable, Lower
Limit or Upper Limit (see Figure 48).
6. Press UP or DOWN keys to disable the alarm or
change the limit values.
FIGURE 48
Adjusting Return Air Alarm Settings

Emergency Ventilation Mode

If the emergency ventilation input at the LC is active,
the system will go into emergency ventilation mode. In
emergency ventilation mode, the economizers on the wall
units will be commanded to 100%. This mode is only
available when connected to the LC.
NOTE: All units will receive the emergency ventilation
command. Wall units not equipped with
economizers will still engage the blower.

Electric Heat Option

Electric Heat Components

Electric Heating Element

The unit can be optionally equipped with 9kw or 18kw
of heat. The 9kw is a single stage heating element. The
18kw option comes equipped with two 9kw heating
elements that operate in two stages. The heating
elements are located downstream of the evaporator
coils and can be accessed through the upper control
panel door.

Thermal Overload

The heater assembly has a thermal overload wired in
series with the heating element. This device has a
cycling limit which opens at 130°F and resets at 80°F.
The limit is also equipped with a redundant thermal
fuse that will open at 150°F.

Electric Heat Operation

The heat strip will be activated on a call for heat. This
call can be generated by the LC or the wall-mount unit
operating in orphan mode.

Electric Reheat Dehumidification

The MEGA-TEC wall-mount unit can be ordered with
optional electric reheat dehumidification. This feature
is indicated by the letter "E" in the 6th character of
the model number. Electric reheat dehumidification is
only available as a factory-installed option that must be
ordered with the unit. It cannot be installed in the field
on an existing unit.
To verify the dehumidification capability of a unit and/
or disable the dehumidification operation:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to System Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Dehum Config
A9 (see Figure 49 on page 34).
NOTE: Capability on this menu will show the unit's
dehumidification capability based on the model
number entered into the wall-mount unit's
controller. This parameter will show either Not
Available or Electric Reheat.
Manual 2100-671C
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