Correct temperature adjustment is the foundation of successful trade in perishable goods. Not only the appearance of the product, but also the safety of consumers, as well as the period of sale of the goods, depend on the accuracy of the set parameters. Errors in adjustment can lead to damage to expensive meat or dairy products, which will entail direct financial losses.
Modern refrigerated display cases are equipped with complex electronic control systems that require a careful approach. The business owner or store staff must clearly understand the difference between the temperature of the air inside the chamber and the temperature of the product itself. These indicators often differ, and you need to focus specifically on the condition of the product.
In this material we will analyze the algorithms of actions for various types of controllers, explain the physics of the cooling process and help you avoid typical mistakes when operating commercial equipment. Proper adjustment will reduce energy consumption and extend the life of the compressor.
Principles of operation of the temperature regime in display cases
A refrigerated display case works on the principle of maintaining a given range, rather than constantly freezing the air. The compressor turns on when the sensor detects that the upper threshold has been exceeded, and turns off when the lower limit is reached. This difference is called hysteresis, and its magnitude is critical for storage stability.
It is important to understand that the temperature sensor is usually located in the air suction zone or on the evaporator. It reads the temperature of the air flow, which then cools the food. Therefore, the value displayed on the display does not always instantly reflect the actual condition of the meat or fish lying on the shelf.
The circulation of cold air in the display case is organized in such a way as to create an air curtain. The optimal air flow speed is 0.2-0.3 m/swhich allows you to effectively cool the product without drying out its surface. Violation of this balance leads to either weathering or insufficient cooling.
The accuracy of the readings is influenced by many factors: loading density, frequency of opening the curtains, temperature in the sales area and even the heating system operating nearby. All these variables must be taken into account during the initial setup of the equipment.
Control interfaces: mechanics versus electronics
All refrigerated display cases can be divided into two large groups according to the type of control: mechanical thermostats and digital controllers. The mechanics are found in older models or budget solutions and are a twister with risks from 1 to 7 or with a designation of degrees.
Electronic systems, such as Pixell, Carel, Eliwell or Dixellprovide much more possibilities. They allow you to set precise values in 0.1 degree steps, adjust the defrost time and control the operation of the fans. However, the complexity of the interface often frightens users.
To access the settings of electronic controllers, you often need to enter the service menu. This is usually done by long pressing a button or key combination. For example, on many models you need to hold the "Set" button for 5-7 seconds until the blinking indicator appears.
Do not try to change parameters without knowing their purpose. Accidentally changing the type of temperature sensor or compressor operation logic can lead to equipment failure. If you are not sure of your actions, it is better to refer to the instructions for a specific model.
Step-by-step instructions for setting up electronic controllers
Let's consider the setup algorithm using the example of popular controllers, which are installed in 80% of modern storefronts. The process requires consistency and attention to detail.
First you need to enter programming mode. Look for a button labeled "Set","P" or a gear icon. Press and hold it for about 5 seconds. The parameter code should appear on the display, for example r1 or SP.
Using the "Up" and "Down" arrow buttons, select the parameter responsible for the temperature set point (Set Point). This is usually the first parameter in the list. Change the value to the required one, for example, +2°C for dairy products or +4°C for gastronomy.
Next you should adjust the differential (hysteresis). This parameter is often denoted as HY or dIF. It determines how many degrees the temperature must rise for the compressor to turn on again. For display cases, the optimal value is 2-3 degrees.
☑️ Setting up the controller
⚠️ Attention: When changing parameters in the service menu, do not change values whose meaning is unknown to you. This is especially true for parameters related to the type of refrigerant or compressor protection, as this can lead to equipment failure.
After making all changes, be sure to save the settings. In most controllers, to do this you just need to stop pressing the buttons and wait 10-15 seconds, or press a special combination. The display will return to the normal mode of displaying the current temperature.
Setting features for different types of products
Different groups of products require strictly defined temperature conditions. There is no universal setting “for everything”, and an attempt to average the indicators will lead to damage to part of the assortment.
For meat displays where fresh meat is stored, it is critical to maintain the temperature in the range from -1°C to +2°C. At higher values, bacteria begin to actively multiply, and at lower values, the product may freeze slightly, losing its presentation.
Dairy products and finished culinary products require a regime from +2°C to +6°C. Stability is more important here than extremely low temperatures. Sudden changes can disrupt the structure of products, especially yoghurts and curd masses.
Frozen goods are stored in freezers at a temperature not exceeding -18°C. In this case, the hysteresis setting should be minimal to avoid defrosting the top layer of product during defrost cycles.
| Product type | Recommended t°C | Max. hysteresis | Shelf life (approximate) |
|---|---|---|---|
| Fresh meat | -1...+2°C | 2°C | 3-5 days |
| Dairy products | +2...+6°C | 3°C | 5-10 days |
| Chilled fish | -2...+2°C | 1.5°C | 2-3 days |
| Confectionery | +4...+8°C | 4°C | up to 7 days |
Diagnostics and elimination of temperature changes
If you have set the correct settings, but the temperature in the display case “jumps” or does not hold, the problem may not lie in the controller. Most often, the cause is external factors or the technical condition of the equipment.
The first thing to check is the loading density. The showcase should not be packed to capacity. There must be a gap between the products and the back wall, as well as between the product and the level of the air curtain for free air circulation.
The second important aspect is the condition of the seals and night curtains. If the rubber profile around the perimeter of the display case is damaged or dirty, cold air leaves and warm air penetrates inside. This causes the compressor to wear out.
It is also worth checking the cleanliness of the condenser. Located most often at the bottom or back, it is covered with a layer of dust that acts as a heat insulator. A dirty condenser cannot efficiently transfer heat, which reduces the overall efficiency of the refrigeration machine.
What to do if the display cabinet makes noise when setting up?
If, after adjusting the temperature, an uncharacteristic noise appears, check whether the trays are touching the body during thermal expansion. A fan may also make noise if ice has frozen on its blades due to an incorrect defrost cycle. In this case, defrosting and checking the heating elements is required.
The influence of loading and placing goods on cooling
Correct display of goods is half the success in maintaining the temperature. There are strict merchandising rules for refrigeration equipment, violation of which nullifies all controller settings.
It is strictly forbidden to block air recirculation lines. Holes or grilles are often visible on the back wall of the display case. If you place a carton of milk close to them, the cold air will not flow along the contour, and a “heat pocket” will form in the far corner of the display case.
Heavy and dense products, such as large pieces of meat or frozen blocks, are better placed closer to the active blast zone (usually the back or special zones). Lightweight packages can be placed closer to the buyer.
When loaded with warm products (for example, immediately after delivery from the supplier), the display case may not be able to cope with a sharp increase in heat. In such cases, it is recommended to temporarily lower the temperature setting by 2-3 degrees, and after the product has cooled, return the settings to normal.
⚠️ Attention: The design of the display case and the effectiveness of the air curtain depend on the humidity in the room. If a powerful humidifier is running in the sales area or, conversely, it is very dry, this can affect the formation of condensation and ice, which will change heat transfer. Check the operating conditions in the equipment passport.
Seasonal adjustment and maintenance of the system
Temperature settings are not static and may require correction depending on the time of year. In the summer, when the temperature in the sales area is much higher, the load on the display case increases.
During hot periods, it may be necessary to reduce the hysteresis or slightly reduce the target temperature to compensate for the heat gain from open doors and visitors. In winter, on the contrary, the equipment can work too efficiently, and there is a risk of freezing of products at the back wall.
Regular maintenance includes not only cleaning, but also checking the calibration of the sensors. Over time, electronics may become slightly inaccurate. Once a year, it is recommended to check the display display readings with the readings of a reference thermometer.
If you notice that the display cabinet has begun to turn on and off frequently (clocking), this may indicate a loss of freon or a malfunction of the thermostat. In such a situation, simple reconfiguration will not help - you need to call a technician for diagnostics.
Why does the display case not maintain the temperature even after adjustment?
There may be reasons there may be several: a refrigerant leak, a malfunction of the temperature sensor, condenser contamination, damage to the door seals, or too high a temperature in the store premises. It is also possible that the product is loaded incorrectly and is blocking the air flow.
How often should the display case be defrosted?
The frequency depends on the model and humidity in the room. Modern display cases with automatic defrosting do this themselves (usually 2-4 times a day). If there is too much ice on the evaporator and it interferes with circulation, manual defrosting and checking the operation of the defrosting heating elements are required.
Can the display case be used as a freezer?
No, it is not possible. Medium-temperature display cases (for gastronomy, meat, milk) are not structurally designed for temperatures below -5°C...-10°C. Trying to set it to -18°C will lead to freezing of the evaporator, breakdown of the compressor and spoilage of food. Low-temperature islands are needed for freezing.
What does the "E1" or "AL" error on the display mean?
These are emergency codes. "E1" most often means a break or short circuit of the temperature sensor. "AL" (Alarm) can signal that the threshold temperature has been exceeded. The exact decoding should be found in the instructions for the specific controller model.
Does the location of the display case affect its operation?
Yes, critically. The display case cannot be placed close to the wall (a gap is needed for ventilation of the condenser), in direct sunlight or next to radiators and thermal curtains. This creates a thermal load.