The Bard MC4002-B is an advanced solid-state dual-unit lead/lag controller engineered for Bard HVAC wall-mount systems that require reliable redundancy control, staged operation, equipment rotation, and alarm monitoring. Designed to manage two connected HVAC units, it supports multi-stage cooling and heating, automatic lead/lag rotation to balance runtime, and selectable sequencing to help maintain stable temperature control in commercial, industrial, telecom, modular, and equipment-room environments.
The integrated enhanced alarm board adds critical system visibility by monitoring power loss, refrigerant lockout, high and low temperature conditions, controller failure, and environmental thresholds. This helps maintenance teams identify faults quickly, reduce downtime, and protect cooling equipment in applications where continuous HVAC performance is essential. The MC4002-B directly replaces the Bard MC4000-B control with alarm and the MC4001-B alarm board, making it a dependable upgrade or service replacement for compatible Bard lead/lag control systems.
Built with solid-state control logic, 24VAC HVAC relay outputs, programmable memory retention, and network monitoring capability, the Bard MC4002-B provides a practical control solution for facilities that depend on coordinated dual-unit operation, alarm reporting, and long-term HVAC system protection.
The Bard MC4002-B is used to control two Bard HVAC wall-mount units in a lead/lag setup. It helps stage system operation, rotate equipment runtime, and provide alarm monitoring for critical cooling applications.
Yes. The MC4002-B is designed for dual-unit HVAC control and supports coordinated operation between two Bard wall-mount air conditioning systems.
Lead/lag control allows one HVAC unit to operate as the primary unit while the second unit acts as a backup or support unit. The controller can rotate operation to help balance runtime and reduce wear on a single unit.
The enhanced alarm board monitors important system conditions such as power loss, refrigerant lockout, high or low temperature events, controller failure, and environmental alarms. This helps facility teams respond faster to HVAC problems.
Yes. The Bard MC4002-B directly replaces the Bard MC4000-B control with alarm and the MC4001-B alarm board.
The MC4002-B is commonly used in telecom shelters, modular buildings, equipment rooms, mechanical rooms, and commercial HVAC installations where continuous cooling and system redundancy are important.
Yes. By rotating lead and lag operation between two HVAC units, the controller helps balance runtime across equipment, which can support longer service life and more even system usage.
The Bard MC4002-B uses 24VAC HVAC relay outputs for compatible control applications.
| Cooling stages | 4 |
|---|---|
| Frequency | 50/60 Hz |
| Heating stages (configured for A/C with electric heat): | 2 |
| Heating stages (configured for Heat Pump): | 4 |
| Operating Temperature | 0 to 120°F (-18 to 49°C) |
| Voltage | 18 to 32V |
| Temperature Accuracy | +/- 1F from 60 to 85°F (16 to 30°C) |
| Approvals | FCC, ETL, CE, and CSA certified |
| Lead/Lag Changeover Time | 0 to 30 days |
| Amperage | 1A |
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Bard HVAC MC4002-B Lead/Lag Controller Installation Instructions
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We can not confirm the exact wire to use for connecting the Bard MC4002-B controller to outdoor unit model number 10111823 based only on the information provided.
The Bard MC4002-B installation information identifies this as a solid state dual unit lead/lag controller and states that field wiring should be connected only to the designated low voltage terminal strips. However, the exact wire type, gauge, conductor count, and connection points would need to be verified against the specific outdoor unit wiring diagram, the MC4002-B installation manual, and applicable local electrical codes.
Because this is an HVAC control wiring application, we strongly recommend that the connection be reviewed by a licensed HVAC or electrical technician familiar with the equipment, the installation, and local code requirements before wiring or installation.
We are not able to provide a confirmed wiring recommendation from the available product information.
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