Helmer Scientific i.Series
®
and Horizon Series
™
Refrigerator - Pass-Thru
Service and Maintenance Manual
360429/A
50
Control Sensor
The temperature controller senses unit cooler temperature through the control probe in the unit cooler. The unit cooler temperature
typically varies from the chamber temperature, so an offset value is used by the control system to compensate for the difference.
The temperature controller adjusts chamber temperature around the refrigerator setpoint.
Determine control sensor offset:
Notes
•
Control Sensor Offset is factory-preset and changing this value is not recommended. Contact Helmer Technical Service
for questions regarding the Control Sensor Offset.
1. View and record Refrigerator Setpoint. (Reference Section 10.3)
2. Allow unit to run with calibrated monitor temperature for several compressor cycles, and record average
monitor temperature
. (If the monitor temperature remains close to the refrigerator setpoint no further action is needed.)
3.
View and record current Control Offset value.
4.
Subtract Refrigerator Setpoint from average monitor temperature and record difference.
5.
Add current Control Offset value to recorded difference determined in previous step to establish new Control Offset value.
Example 1
Example 2
Refrigerator setpoint is 4.0
Refrigerator setpoint is 4.0
Average monitor temperature is 5.2
Average monitor temperature is 2.8
Current Control Offset is 0.3
Current Control Offset is 0.3
Subtract: 5.2 - 4.0 = 1.2; difference between average temperature
and setpoint.
Subtract: 2.8 - 4.0 = -1.2; difference between average temperature
and setpoint.
Add: 0.3 + 1.2 = 1.5; new control offset value
Add: 0.3 + (-1.2 )= -0.9; new control offset value
Enter the new offset value:
1. Press and hold
Up
and
Down Arrows
simultaneously for 3 seconds to enter program mode.
2. Display will show .C or .F to indicate Celsius or Fahrenheit.
3. Press
MODE
until only CONTROL lamp flashes.
4. Hold
SET
, then press
Up
or
Down Arrow
to change setpoint.
5. Release
SET
button. New setting is saved.
6. Press and hold
Up
and
Down Arrows
simultaneously for 3 seconds to exit program mode.
Upper Rail
The Upper Rail Limit is the maximum control temperature at which the compressor will turn on.
Lower Rail
The Lower Rail Limit is the minimum control temperature at which the compressor will turn off.
NOTICE
The Upper Rail and Lower Rail values are factory-preset and should not be changed unless directed by
Helmer Technical Service.
Non-Configurable Alarms
The Power Failure and Door Open alarms indicate operational conditions which may require the attention of the operator or a
qualified service technician. The Power Failure alarm will activate immediately upon loss of power. The Door Open alarm will
activate once the door has remained open for approximately three minutes. These settings are factory-preset and may not
be changed.
Horizon Series
