Helmer Scientific i.Series
®
and Horizon Series
™
Freezer - Undercounter
Service and Maintenance Manual
360417/A
23
Primary Monitor Probe
Verify the primary monitor probe is reading the chamber temperature correctly by comparing the probe reading to the temperature
measured by a calibrated reference thermometer. If the probe is not reading correctly, change the value displayed on the monitor.
The factory default setting for the primary probe is -30.0°C.
Notes
• Ensure product simulation bottle is full of solution.
• The probe in the bottle is connected to the monitoring system and senses chamber temperature. This probe
activates the temperature alarms but does not affect temperature control.
Calibrate Primary Monitor Probe
1. Remove the primary monitor probe from the probe bottle.
2. Unscrew the cap from the bottle.
3. Attach a calibrated independent reference thermometer traceable per national standards to the primary monitor probe,
and place them in the bottle. The probe and thermometer should be immersed at least 2” (50 mm).
4. Close the door and allow the chamber temperature to stabilize.
5. Observe and note the thermometer temperature. If the independent thermometer corresponds to the displayed
temperature, proceed to
Step 11
.
6.
Subtract the displayed temperature reading from the independent probe reading to determine the offset value.
7. Enter the Settings password (default password is “1234”).
8. Touch,
i.C³ APPS
,
Settings.
9. Touch
Sensor Calibration
.
10. Touch the minus (
–
) or plus (
+
) on the
corresponding
spin box to increase or decrease the value by the value
calculated in
Step 6
. The message “New Setting Saved” appears next to the spin box.
11. Remove the thermometer from probe.
12.
Replace and secure the bottle cap, ensuring a tight fit.
13. Place the probe in the bottle, immersing at least 2” (50 mm).
Control Probe
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.
Chamber temperature will be controlled as required to match the temperature set point based on the control probe reading.
Determine Control Probe Offset
NOTICE
•
Control Probe Offset is factory-preset and should not be changed. Contact Helmer Technical Service for instructions
regarding changing the Control Sensor Offset.
•
Monitor temperature must be verified and accurate prior to adjusting the Control Sensor Offset.
1. View and record the Freezer Setpoint.
2. Allow the unit to run with a calibrated monitor temperature for several compressor cycles, and record the average
monitor temperature
.
3.
View and record the current Control Offset value.
4.
Subtract the Freezer Setpoint from the average monitor temperature and record the difference.
5.
Add the current Control Offset value to the recorded difference determined in the previous step to establish the new
Control Offset value.
Example 1
Example 2
Freezer setpoint is -30.0
Freezer setpoint is -30.0
Average monitor temperature is -29.2
Average monitor temperature is -31.2
Current Control Offset is 0.3
Current Control Offset is 0.3
Subtract: -29.2 - (-30.0) = 0.8 (
difference between average temperature and setpoint)
Subtract: -31.2 - (-30.0) = -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)
i.Series
