Evaporator Control

Standard

• Setpoint scheduling (zone independent):
  • Four programmable setpoint groups (cooling setpoint, deadband, high alarm, low alarm, and heating setpoint option).
  • Three daily schedules each with eight time slots.
  • Manual override provided for schedule number and setpoint group.
• Air unit fans may be individually set to cycle with temperature or remain running. A programmable fan cycle off-time delay and/or on-time delay is also provided.
• When the fans for a zone are cycled off due to temperature, the fans may be cycled on for a short period of time to sample the room air before resuming normal operation.
• Support for various zone defrost types (hot gas, water, air, etc.)
• Zone high temperature alarms are inhibited during defrost cycle and for a user programmable delay after defrost completion.
• Manual override control of zone state (cooling, stop, manual, defrost, pump-out).
• Adaptable to match each zones specific valve station configuration.
• Defrost scheduling:
  • Defrost based on liquid feed runtime or fixed time schedules.
  • Programmable defrost times using three daily schedules with eight time slots.
• Power fail staging to slowly bring zones on-line after power failures based on user defined staging time and zone priorities.
• User-programmable setpoints to enable and disable defrosting based on head pressure
• Ability to inhibit defrosting of zones when no compressors are available.
• Ability to terminate defrost manually to force zone back to cooling state.
• Ability to separate zones into different defrost queues to select number of zones which can defrost at a time

Options

• Zone shutdown due to NH3 detection or other user defined conditions.
• Demand defrost based on discrete input, temperature differential across the coil or fan motor current.
• Priority defrost of pre-defined zones or based on user issued command.
• Heating option allows zone to maintain a heating setpoint. Optional ability to disable heating based on user-defined conditions.
• Variable speed fan control using PID control loop based on user defined weighted average between room air and return air temperature sensors
• Two speed fans, variable speed fans, or variable suction regulator control.