The Bard MC4002 Advanced Solid State Dual Unit Lead/Lag Controller is designed to automatically manage and sequence two HVAC units, ensuring balanced runtime and dependable temperature control for mission-critical environments such as telecommunications shelters, equipment rooms, and commercial facilities.

This controller provides four stages of cooling and up to four stages of heating (when configured for heat pumps), allowing precise control of systems equipped with economizers, two-stage compressors, or dual compressor configurations. The MC4002 ensures proper staging and equipment rotation to reduce wear and improve overall system reliability.

A built-in digital LCD display shows building temperature and allows simple programming of controller functions. Front panel indicators display active cooling or heating stages along with the currently designated lead unit, providing clear operational visibility for technicians and operators.

The MC4002 also includes features such as humidity control capability, generator run input, smoke/fire shutdown circuit, and remote sensor compatibility, making it suitable for a wide range of specialized HVAC installations.

Unlike upgraded MC4002 variants, the base MC4002 model does not include alarm relay boards or Ethernet communication, but it provides the full lead/lag control platform and can serve as the foundation for systems that do not require advanced alarm monitoring.

Key Features

• Controls two HVAC units in automatic lead/lag rotation

• 4 stages of cooling control

• Up to 4 stages of heating when configured for heat pumps

• Compatible with systems with or without economizers

• Designed for 2-stage or dual compressor systems

• Digital LCD display for temperature monitoring and programming

• LED indicators for active stages and lead unit status

• Local temperature sensor included

• Supports up to two remote temperature sensors

• Humidity control capability with optional humidity controller

• Smoke/fire shutdown circuit

• Generator run feature to prevent A/C operation during generator testing

• Selectable fan control modes

• Anti-short cycling compressor protection

• Rugged 20-gauge metal enclosure

Important Model Differences

The MC4002 is the base controller in the MC4002 series.

Other models in the series add additional capabilities:

The base MC4002 is ideal for installations that require lead/lag control and multi-stage HVAC management without remote alarm monitoring or network connectivity