Frozen Beverage Temperature Offset

Frozen Beverage Temperature Offset


How-To Guide :: Frozen Beverage :: Temperature Offset

All Spaceman Frozen Beverage machines have analog controls and analog thermostats for the hoppers and cylinders.  These analog thermostats control the cooling to the hoppers during freeze or standby modes, and to the cylinders in standby mode only.  By default, these thermostats are set to 4oC, or 39oF, by the factory.  Often times, this thermostat value may drift from the actual temperature of the product.  This is completely normal and due to the fact that the thermostats are not touching the product, but rather measuring the temperature through the stainless steel hopper shell.  It may be required from time to time to adjust these thermostats in order to account for an offset such that the actual temperature of the product inside the hoppers is not too warm or too cold.

Special Note: The cylinder temperature does NOT control the viscosity and is not used in regular Freeze mode.

Note: For machines with two hoppers, there are two thermostats, one on each side of the machine.  Each thermostat can call for hopper cooling, so it is very important that the temperature and fill levels of both hoppers remains approximately equal.  If you fill one hopper with warm product, and one with cold product, the thermostat measuring the warm product will call for cooling, however, both hoppers will be cooled as there is only one refrigeration system.  This could lead to the side with cold product over-cooling and freezing up.  For this reason, Spaceman recommends filling hoppers only with pre-chilled product, and keeping hopper levels between the two sides as close to the same fill level as possible.


Testing Thermostats

It is easy to determine the temperature the thermostat is actually reading.  To do this, turn the thermostat dial up or down until you hear a click.  The temperature at which you hear the click is the temperature that the thermostat is currently reading.  If you are in a noisy environment, you can likewise test the thermostat by connecting an Ohmmeter to the output terminals of the thermostat.  The thermostat will switch from closed (0 ohms read) to open at the temperature that the thermostat is currently reading.  Generally, thermostats that have failed will not click on or off at any temperature or will be greater than 10 degrees difference from the actual temperature measured (this is assuming that the product in the hopper is within the temperature range of the dial on the thermostat).

Adjusting Hopper Temperature Offset – With Product in Machine

These instructions are for adjusting the hopper temperature offset with product already installed in the machine.  If your machine has two hoppers, follow these instructions for both hoppers / thermostats.

  1. Remove the side panel(s) from the machine
  2. Using a food-grade thermometer, measure the temperature of the product inside of the hopper in degrees Celsius.   This is the Temperature of Hopper
    Note: If the product has lightly frozen around the outside of the hopper, it is highly recommended to first allow the hoppers to thaw by turning power off to the machine or follow the steps below to set offsets using water.
  3. Notate the initial setting of the Hopper Thermostat.  This is your Thermostat Setting.
  4. Turn the Hopper Temperature dial slowly for the hopper you are measuring until you hear a click.  The temperature at which you hear the click is the Temperature of Thermostat.  You should repeat this step two or three times rotating the dial in both directions to properly identify the correct temperature.
  5. Measure the temperature offset as follows:
    Offset = Temperature of Thermostat - Temperature of Hopper
    Ex: 2 oC Degrees Temperature of Thermostat - 1oC Measured in Hopper = Offset of 1 oC
  6. Your new thermostat setting is: Thermostat Setting + Offset
    Ex: 4oC original Thermostat Setting + 1oC Offset = 5oC new thermostat setting
  7. Adjust the thermostat to the New Thermostat Setting.  Allow the machine to operate for several hours before attempting to adjust again.
  8. If the thermostat dial reads more than +/- 2 C different from the measured temperature, you may need to calibrate the thermostat (see below).
Note: You should always measure the actual product temperature in your hoppers on a regular basis to ensure they remain below 42 oF for food safety.  


Calibrating Analog Thermostats
If the offset on your thermostat exceeds 3-4 degrees Celsius, a manual calibration of the thermostat may be required.  This calibration will allow the thermostat to more closely match the actual measured product in the hopper or cylinder. 
  1. Power off the machine and unplug from the wall.
  2. Remove the side panel(s) from the machine using a flat head screw driver or appropriate Allen key depending on your model.
  3. Locate the thermostat that needs to be adjusted by performing Steps 1-4 of the Offset steps above and calculate the offset calibration that is required.  
  4. Note the orientation of the dial on the thermostat, and remove the dial from the thermostat.

  5. Notate the orientation of the mounting plate, especially the orientation of the triangle indicator.  This must be reinstalled in the same orientation.

  6. Using a Philips head screwdriver, remove the mounting plate and remove the thermostat from the mounting bracket.

  7. Using needle nose pliers, carefully but firmly adjust the calibration screw around the dial of the thermostat. 

    1. If the temperature on the dial needs to be increased (i.e. the dial is reading below the measured temperature), adjust the calibration screw clockwise. 
    2. If the temperature on the dial needs to be decreased (i.e. the dial is reading above the measured temperature), adjust the calibration screw counter clockwise.
    3. The calibration screw requires minimal adjustment.  This screw is effectively moving the dial orientation in relation to the triangle indicator.  
    4. To verify the calibration, you can temporarily reattach just the mounting plate with triangle indicator and dial in the appropriate orientation.  When the correct calibration is achieved, you will hear the thermostat click at the temperature that matches the measured temperature.  Repeat steps 2-6 until the correct calibration is achieved.
  8. Reattach the thermostat to the mounting bracket and mounting plate.  Ensure the mounting plate is reinstalled in the appropriate orientation.
  9. Reattach the dial to the thermostat.  
  10. Perform Steps 1-4 of the Offset steps above and ensure the thermostat clicks on and off within +/- 1 degree Celsius of the measured temperature in the hopper or cylinder.
  11. Adjust the dial to 4 degrees Celsius for food safety.
  12. Reinstall the side panels and resume normal operation.




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