Bard MC4000 SERIES, Installation Instructions & Replacement Parts List

Page: 16 / 40

Manual 2100-563
Page
16 of 40
CONTROLLER WIRING
The MC4000 can be used for controlling two (2) air
conditioners with or without economizers. It can also be
configured for two (2) heat pumps without economizers.
Units with economizers will connect differently than
units without economizers; therefore, it is important to
use the correct connection diagram.
There are older style EIFM economizers and newer style
ECONWMT economizers that the MC4000 controller
system can work with, and also an option for a remote
Ethernet communication board. Therefore, it is
important to select the correct low voltage hook-up
diagram. See Table 1 — Hook-Up Diagram Selection
on Page 17.
SECURITY (LOCKING) FEATURE
The MC4000 controller can be locked such that
unauthorized persons cannot make any changes to
temperature set points or any other selectable parameters
of the controller system.
The ON/OFF and Comfort buttons remain fully active
for their normal intent. The Advance/Change/Save
button remains active for the Advance feature only,
which allows the position of the lead and lag air
conditioners to be swapped (reversed). The Program
button remains partially active - allowing the review of
temperature sensor(s) actual reading of temperature, and
the current settings/choices that have been chosen.
However, no changes can be made when the controller is
locked, and if the change button is pressed when in the
Program mode, the display will come up showing
“Locd” instead of flashing the selectable choices for that
parameter. The default (DEF) reset capability is also
disabled when the controller is in locked mode.
Locking and Unlocking the MC4000 Controller:
1. Locking the controller requires using 3 buttons
while the controller is in the normal operating (run)
mode.
2. Press and hold the Advance/Change/Save button
and the Up and Down arrow buttons simultaneously
for 20 seconds until the display shows “Locd”.
3. To unlock the controller, press the Change, Up and
Down arrow buttons simultaneously for 20 seconds
until the display reads “uLoc”.
GENERATOR RUN FEATURE
If desired, the MC4000 controller can be signaled from a
standby generator system to lockout (disable operation)
of the lag air conditioning system. This is sometimes
mandated if the generator size is not sufficient to handle
the building load (amperage) and that of both air
conditioning systems.
A normally closed (NC) dry contact as part of generator
controls is required. These contacts must open when the
generator is started, and such action will signal the
MC4000 controller to this condition and disable lag air
conditioner run function.
A wire jumper is factory-installed across the G1 and G2
terminals or main controller board. To utilize the
generator run feature, remove the jumper from G1 and
G2, and connect the generator normally closed (NC)
contacts that will open-on-run generator condition to the
G1 and G2 terminals.
BACKUP DC POWER CONNECTION
There are input connections available for -24VDC or
-48VDC (-20 to -56V) backup power connection.
Making this connection will maintain microprocessor
operation, front panel display, LED signaling, and alarm
relay operation during periods of commercial power
outages and when no standby generator is available.
This circuit is protected by a replaceable .5A (500mA)
250V fuse.
IMPORTANT:
The shelter DC battery power must
be connected to the controller and wired as shown
in controller wiring diagrams.
The backup DC power connection is polarity
sensitive. If polarity is reversed, the controller will
not function on backup power, no display and no
alarm functions will be evident.