Wizard W3LL Zone Lead-Lag Cooler Control System

An all-in-one system control that combines with temperature control, monitoring and alarming; defrost;  door ajar alarm; entrapment alarm; and leak detection.

Link to Cut Sheet

click to enlarge



The Wizard Lead-Lag Control is a hard wired, permanently mounted electronic control panel that is designed for improving operation of the refrigeration system and maintaining a stable cooling temperature inside the cooling room. This Control has the simplicity of its front panel, which offers minimum yet versatile keys and functions.

Operating Capacity

  Single temperature probe input

  One entrapment alarm push button input

  One door switch input

  One refrigerant Leak Sensor input

  Two defrost relay outputs

  Two fan control relay outputs

  Two liquid solenoid relay outputs

  Two levels of refrigerant leak alarm relay outputs, 2 relays per alarm level. One Relay for each level is silence-able and one is non silence-able

Lead-Lag Operating Mode

The Lead-Lag system controls two evaporators in the same cooling room. One system is operated as the primary system while the other system is idle as the secondary system. The Control maintains it room temperature utilizing the cooling capacity of the master system. The WLL has the option of activating the Secondary System should the space temperature increase above a second cooling stage setpoint.  The Control will automatically switch the master system to secondary system to maintain the equal run time on both systems. The Fans on each system are ON while in cooling mode.

The Control alternates the systems after three different situations:

The systems alternate when the temperature within the room is met. The evaporators operate in sequence. The "Primary System" will become idle, the system idle for the longest period of time will become primary.

Defrost. The systems will switch to secondary immediately following a defrost cycle.

Two hours of continuous operation. Should the refrigeration system operate for a continuous two hour period without the room temperature satisfied, the controller will switch to one of the idle systems and activate the system alarm.

FIFO (Round-Robin) Operating Mode

The Controller runs the evaporators based on first-in, first-out mode (FIFO). The Controller monitors the room temperature and maintains the room temperature by utilizing the cooling capacity of the evaporators. The evaporator liquid line which was turned on first will be the one to be turned off when cooling capacity requirement is reduced. This rotation scheme equalizes the run time on each evaporator. This mode is activated by menu selection and by shorting the inputs at the MAX. COOLING FIFO activation input terminals.

Defrost Operation

The entire system will defrost simultaneously, eliminating conflicts between each system. Defrost consists of four cycles: Pump down, Defrost, Drip cycle, Fan on delay cycle.

All the cycle times can be adjusted. The main defrost cycle on each evaporator will be terminated by the closure of the temperature termination input(T-stat) or by termination temperature probe reaching a preset temperature.

Entrapment Alarm

User selectable option. When Entrapment input is opened (Input is connected to a N.C. Entrapment Push Button inside the cooling room), the Control will enter into entrapment alarm mode immediately; the system alarm relays are turned on, the front panel alarm light are flashing and the buzzer is turned on. Entrapment Alarm can only be reset manually by pressing the ALARM RESET key.

Door Open Alarm

User selectable option. When door to the room is opened (Door Alarm Input is closed), the Control will start counting down the door alarm delay time. After the delay time expired and the door is still opened, the Control will enter into door alarm mode; the system alarm relays are turned on, the front panel alarm light are flashing and the buzzer is turned on. By choice, the alarm can be reset when door is closed or the alarm has to to be reset manually.

Refrigerant Leak Alarm

User selectable option. The Control can be used to monitor refrigerant leaks with the installation of a Sherlock Refrigerant Sensor. There are two alarm levels. Each alarm level has two alarm relay outputs. One of the alarm outputs is silence-able. This relay output can be connected to Audiovisual devices for alarming. The non-silence-able relay output is connected to EMS, BAS or local ALARM CENTER for remote and service alarming. Alarm levels and alarm delays are adjustable.