Bard MC4000 Controller Wiring, Security Locking Feature, Generator Run Feature

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.

Manual	2100-563C
Page	16 of 40