Correct setting of the temperature regime in the display refrigerator is fundamental a condition for preserving the presentation and safety of products. Errors at this stage often lead to damage to the product, proliferation of bacteria, or, conversely, to freezing, which destroys the structure of vegetables and fruits. The business owner or store staff must clearly understand how it functions thermostat and what the indicators inside the chamber depend on.
Modern models of display cases, be it Polar, Brandford or Ariada, are equipped with electronic or mechanical controllers requiring precise calibration. Incorrectly set values can cause customer complaints and financial losses. In this article, we will analyze in detail the algorithms of action for various types of equipment and eliminate common misconceptions about the operation of the refrigeration circuit.
Before proceeding with the adjustment, you need to make sure that the display case is installed correctly, the distances from the walls are observed, and the ventilation grilles are not closed. Only if these conditions are met refrigeration unit will it work normally and the sensor readings will be reliable. Ignoring basic installation rules negates any attempts at fine tuning.
Principle of operation of the thermostat and sensors
The basis of the control system is a thermostat or an electronic controller that reads data from the temperature sensor and controls the compressor. Mechanical models use a capillary tube filled with gas or liquid that expands or contracts as thermal conditions change. Electronic systems, such as Dixell or Careluse thermistors that transmit data to a microprocessor with high accuracy.
It is important to understand that the sensor is often not installed in the center of the chamber, but in a specific area, for example, at the evaporator or on the back wall. This means that the actual temperature of the products may differ from the readings on the display. Heat transfer inside the display case occurs unevenly, and the task of setting is to minimize these fluctuations.
⚠️ Attention: The location of the temperature sensor is critically important. If it is displaced or touches the metal parts of the housing, the readings will be incorrect, which will lead to cyclic turning on and off of the compressor.
Electronic controllers allow you to set not only the target temperature, but also hysteresis - the difference between turning on and off. A narrow hysteresis ensures stability, but increases equipment wear, while a wide one allows for large fluctuations, saving the resource of the compressor. What is hysteresis in simple words? Hysteresis is the temperature range in which the compressor does not respond to changes. For example, if the temperature is set to +4°C and the hysteresis is 2°C, the compressor will turn on at +5°C and turn off at +3°C. This prevents the engine from starting too frequently. compressor.
What is hysteresis in simple words?
Hysteresis is the temperature range over which the compressor does not respond to changes. For example, if the temperature is set to +4°C and the hysteresis is 2°C, the compressor will turn on at +5°C and turn off at +3°C. This prevents the engine from starting too often.
Differences between mechanical and electronic controllers
There are two main types of control on the commercial equipment market. Mechanical controls, often a rotary knob numbered 1 through 7, require a rule-of-thumb approach. The numbers here do not indicate degrees Celsius, but only indicate the intensity of cooling. Position "1" corresponds to the minimum cold, and "7" to the maximum.
Electronic control panels provide the user with accurate data. The display shows the current temperature in the chamber and the set value. Systems such as Eliwellallow you to program defrost modes, fans and alarms. For setting, a combination of buttons is used here, which eliminates accidental changes of parameters by personnel.
When switching from mechanics to electronics or when working with both types, it is important to take into account the inertia of the system. After turning the knob or changing the digital value, time must pass for the refrigerant to circulate through the system and change the thermal regime. Instant result will not be in any of the cases.
- 🌡️ Mechanical regulators are cheaper to repair, but less accurate and depend on the network voltage.
- 📟 Electronic controllers show precise degrees and have a self-diagnosis function.
- ⚙️ Setting up electronics requires knowledge of parameter codes, while mechanics are adjusted “by eye.”
Algorithm for setting a mechanical thermostat
If your showcase is equipped with a rotary manually, the setup process turns into a sequential experiment. First, you need to move the regulator to the middle position, usually the number 3 or 4. After this, the display case should work normally for at least 6-8 hours to stabilize the processes.
For control, use an external thermometer placed in the center of the chamber at the level of the middle shelves. Do not rely on “touch” sensations or the degree of freezing of water in a glass, as these methods give a large error. Measurement accuracy is the key to success in setting.
If the temperature is higher than normal, gradually increase the regulator value. If food freezes near the back wall, reduce it. Remember that changing the position of the knob even by one division can change the temperature inside by 2-3 degrees.
☑️ Checking the mechanical settings
A common mistake is trying to set the “maximum cold” immediately after loading warm products. This leads to freezing of the evaporator and engine damage. The setup should be done on an empty or partially filled display case at a stable room temperature.
Setting up electronic controllers (Dixell, Carel, Eliwell)
Working with electronics requires care and the availability of instructions for the specific controller model. The interfaces may differ, but the logic remains the same. To enter the settings menu, you usually need to hold down the settings button (often designated as Set) for a few seconds until the parameter code appears.
The main parameter that interests you is often designated as SP (Set Point) or is simply displayed on the main screen when pressed briefly. This is where you set your target temperature. However, there are also hidden parameters, such as differential, compressor start delay and defrosting modes.
Example of sequence for Dixell:1. Press and hold SET (3 sec).
2. "P1" (or another code) will appear on the screen.
3. Use the arrow buttons to find the “St” (Set Point) parameter.
4. Press SET, change the value using the arrows.
5. Press SET to save or wait for auto-saving.
It is not recommended to change the factory settings for defrosting cycles unless absolutely necessary. A broken timer can cause the display case to heat up instead of cool. If you are not sure of the value of the parameter, it is better to contact a specialist in refrigeration equipment.
⚠️ Attention: Accidentally changing parameters in the service menu of the electronic controller can lead to equipment failure. Write down the original values before making any changes.
Temperature conditions for different types of products
There is no universal temperature for all products. Meat, fish, dairy products and vegetables require different storage conditions. Setting the wrong mode in a universal display case can lead to damage to one of the product groups.
For example, dairy products require stable cold in the range of +2...+4°C, while some fruits at this temperature lose their taste and aroma. Commodity neighborhood and the correct temperature regime are inextricably linked.
| Product type | Recommended temperature | Storage features |
|---|---|---|
| Meat and offal | 0°C ... +4°C | Require stable cold, are afraid of freezing |
| Fish and seafood | -2°C ... +2°C | The shortest shelf life, you need extreme cold |
| Dairy products | +2°C ... +6°C | Sensitive to changes, quickly turn sour |
| Vegetables and fruits | +6°C ... +12°C | Afraid of low temperatures (loss of taste, blackening) |
| Confectionery | +2°C ... +8°C | Humidity is important so as not to dry out |
If mixed groups of products are stored in your display case, be guided by the requirements of the most perishable product. However, it is better to use specialized equipment for each category. Storing vegetables at temperatures below +5°C often leads to irreversible changes in the structure of the fetal tissue.
Factors affecting temperature stability
Even a perfectly configured storefront may not work correctly due to external factors. The first and main enemy is the heat load from the room. If the store is hot, and the display case is in a draft from the air conditioner or at the entrance, compressor it will work for wear, not achieving the specified parameters.
Loading density also plays a role. An empty display case loses cold faster when opened, but also cools faster. An overloaded display case, where products block the ventilation openings, disrupts air circulation. Cold air is heavier than warm air and must fall down, washing the goods.
- 🚪 Frequent opening of doors or disruption of the air curtain in open display cases.
- 🧊 Ice on the evaporator, which acts as a heat insulator and interferes with cooling.
- 💨 Condensers clogged with dust, reducing the efficiency of heat transfer.
Regular cleaning of the condenser and checking the integrity of the door seals will help maintain the set temperature with less energy consumption. Ignoring maintenance results in the temperature setting becoming useless.
Why does the display case not maintain the temperature at night?
At night, the room temperature may drop, which affects the operation of the thermostat. It is also possible to have an energy saving mode or a night blind that is not fully lowered. Check the night mode settings in the electronic controller.
Is it possible to store products in a display case without packaging?
Not recommended. Opened products lose moisture faster (shrinkage) and absorb foreign odors. In addition, product particles can get onto the sensors or into the drainage, causing malfunctions.
How often should you check the temperature?
At least twice a day (morning and evening) with a log entry. For critical products (fish, meat), monitoring should be more frequent. Electronic systems with remote monitoring simplify this task.
What to do if the temperature fluctuates?
Check the tightness of the doors, the presence of ice, the operation of the fans and the cleanliness of the condenser. If the mechanical parameters are normal, the thermostat may be faulty or there is not enough refrigerant.