How to set the temperature in a display refrigerator

Correct setting of the temperature regime in a display refrigerator is a critical condition for maintaining the presentation of products and compliance with sanitary standards. Incorrectly set parameters can lead to damage to perishable goods or, conversely, to their freezing, which reduces consumer value. Owners of retail outlets are often faced with the need to manually calibrate equipment, especially after loading a new batch of goods or changing the assortment.

Modern retail equipment is equipped with various control systems, from simple mechanical thermostats to complex electronic controllers. Understanding the principles of operation evaporator and the compressor will help you avoid common mistakes during operation. In this article we will analyze in detail the configuration algorithms for various types of equipment and controllers.

It is worth noting that each type of product requires its own microclimate. Dairy products, meat, vegetables and frozen semi-finished products have fundamentally different storage requirements. Ignoring these differences leads to losses and customer complaints.

Principles of operation of the cooling and thermoregulation system

The basis for maintaining the climate in the display case is the cyclic operation of the compressor, which is controlled by temperature sensors. When the internal air heats above a preset threshold, the controller sends a signal to start the compressor. Cooling continues until the temperature drops to the lower limit, after which the system goes into standby mode.

The key element here is thermostat or an electronic equivalent that reads the readings from the sensor. It is important to understand that the sensor can be located in different places: inside the air channel, on the back wall or directly in the product display area. The accuracy of regulation and the speed of the system's response to changes depend on the installation location.

Electronic controllers, such as Dixell or Evco, allow you to set not only the target temperature, but also hysteresis - the difference between turning the compressor on and off. Wide hysteresis saves engine life, but allows large climate fluctuations. A narrow hysteresis provides stability, but causes the compressor to turn on more often.

⚠️ Attention: Do not install the temperature sensor in close proximity to the evaporator fan or defrost heating element if the cabinet design allows it. This will lead to incorrect readings and chaotic operation of the equipment.

It is also necessary to take into account the thermal load. If you have just loaded a large amount of warm goods into the display case, the system may not be able to cope with cooling if the parameters are set too harshly. In such cases, a temporary adjustment of the settings or pre-cooling of the products in the warehouse is required.

📊 What type of controller is installed on your display case?

Dixell (digital)

Evco (digital)

Mechanical thermostat (twist)

I don’t know / Other

Setting mechanical thermostats in old models

Old-style display cases or budget models are often equipped with mechanical regulators. They are a device with a rotary knob and a scale, usually from 1 to 7 or marked Min/Max. In such systems there is no digital display, so the setting is done “by eye” or using an external thermometer.

The principle of operation is simple: turning the knob changes the tension of the spring inside the thermostat, which affects the temperature at which the contacts open. However, the scale on the handle does not correspond to degrees Celsius. The number "3" does not mean +3°C. These are conventional units of cooling power.

For precise adjustments, you will need an external digital thermometer. Place its probe between the product packages in the center of the display case and wait for stabilization (usually 30-60 minutes). If the temperature is higher than normal, turn the knob towards higher values ​​(Max or 7). If the food begins to freeze, reduce the value.

• 🌡️ Calibration: Check the temperature with an external thermometer every 3-4 hours during the day after changing the settings.
• ❄️ Seasonality: In the summer, when the room is hot, the mechanics often have to be turned towards maximum cold, and in the winter - weakened.
• ⚙️ Wear: Over time, the contacts of the mechanical thermostat burn out, and the adjustment range narrows, requiring replacement of the unit.

The main disadvantage of mechanics is inertia and inaccuracy. Sudden power surges in the network can disrupt the settings, and the sensor itself “floats” over time. Therefore, owners of such display cases are recommended to keep a log of temperature measurements in order to notice deviations in time.

Working with electronic controllers Dixell and Evco

Modern display cases are universally equipped with electronic controllers that provide high accuracy. The most common brands are Dixell (XR, XR70CX series) and Evco (EVK series). Their interface is similar: a digital display and several control buttons. Setup is done by entering the settings menu.

To enter the settings menu, you usually need to press and hold the "Set" button for 3-5 seconds. The parameter code will appear on the display, for example, SP (Set Point) or St. This is the target temperature. The value is changed using the "Up/Down" or "+/-" buttons.

An important parameter is differential (Diff). It determines how many degrees the temperature must rise above a set point for the compressor to turn on again. For example, if Set Point = +4°C and Diff = 2°C, then the compressor will turn on at +6°C and turn off at +4°C.

Below is a table of the main parameters for popular controllers:

Parameter	Designation (Dixell/Evco)	Function description	Recommended value (Average temp.)
Setpoint	SP / St	Target temperature	+2...+6 °C
Differential	dIF / di	On/off difference	2...4 °C
Fan delay	FdI / Fd	Fan start delay	0...3 min
Defrost interval	IdE / Int	Time between defrosts	6...8 hours

When working with electronics, it is important not to reset factory settings that you do not understand. For example, changing the parameter responsible for the type of sensor (NTC or PTC) will cause the controller to stop seeing the temperature and generate an error E1 or E2. In this case, resetting to factory settings will help (parameter dEF or a combination of buttons).

☑️ Check before changing controller settings

Record the current values of all parametersMake sure that the display case is connected to the network stableHave instructions for a specific controller model on handPrepare an external thermometer for checking

Done: 0 / 4

Setting specifics for different types of products

Universal temperature does not exist for all products. It would be a mistake to set the mode to “+2°C” for storing vegetables or “+8°C” for fresh meat. Each type of product dictates its own conditions, and the display case must be configured accordingly.

For dairy products and ready-made dishes, the optimal range is considered to be from +2°C to +6°C. At higher temperatures, bacteria begin to actively multiply, reducing shelf life. At lower temperatures, milk may curdle and yoghurts may lose structure. Stability is critical here, so the compressor differential should be set to a minimum (1.5-2°C).

Vegetables and fruits require a special approach. They need temperatures above zero, usually +8...+12°C, and high humidity. If you set the display case as for meat (+2°C), the vegetables will “burn” from the cold, turn black and lose their presentation. Some display cases even have a special “Vegetables” mode, which turns off intense airflow so as not to dry out the product.

⚠️ Attention: Frozen foods (dumplings, deep-frozen meat) require a temperature no higher than -18°C. An ordinary medium-temperature display case is physically unable to provide such a mode, even if the settings are turned up to maximum. For this you need low-temperature islands or chests.

Meat gastronomy and fish are sensitive to overdrying. For them, it is important not only to set the correct temperature (+2...+4°C), but also to adjust the operation of the fans. Too powerful an air flow will quickly dry out a cut of meat, forming a dry crust. In controllers, this is regulated by the operating parameters of the evaporator fan.

What to do if the display case does not maintain the desired temperature for vegetables?

Often the problem is not in the settings, but in the design. If the display case is intended for meat (with powerful airflow and low temperature), you cannot put vegetables there. Try closing some of the ventilation holes or using thermal curtains, but it is better to use specialized equipment.

Adjusting defrosting cycles

During operation, frost will inevitably form on the display evaporator. Moisture from the air and food condenses on cold pipes and freezes. If this ice is not removed, it will block the air flow and the refrigerator will stop cooling, although the compressor will hum non-stop.

The process of removing ice is called defrosting (Defrost). In electronic controllers, you can set two main parameters: interval (after how many hours to start defrosting) and duration (how long to heat the heating element or stop the compressor).

There are two main types of defrosting:

• 🔥 Heating element: Heating elements are turned on, which quickly melt the ice. Requires precise timing adjustment so as not to burn the plastic of the display case.
• 💨 Cyclic (natural): The compressor simply turns off for a long time, and the ice melts from the heat of the air. Less effective, but safer for products.

If you notice that the back wall of the display case is covered with a “coat” of ice, and the temperature inside is rising, it means that the defrost cycle is set incorrectly or is faulty. Increase the defrost duration (parameter ddF or Md) by 2-3 minutes. However, do not set the defrost for too long, otherwise the food will have time to defrost.

It is important to set the correct completion of the defrost. The controller should turn off the heating not according to the timer, but according to the temperature of the defrost sensor (usually +10...+15°C on the evaporator tube). This will prevent overheating. After defrosting is completed, a pause is often included before starting the compressor, so that drops of water do not fall on the hot evaporator and form new ice instantly.

Diagnostics of problems and typical errors

Even a correctly configured display case may not work correctly due to external factors or malfunctions. The most common problem is that the display case “does not keep the cold.” Before calling a technician, check the banal things: whether the night curtains are closed tightly, whether the condenser (the grille at the back or below) is clogged with dust, whether the display case is in direct sunlight.

If an error appears on the display, decoding will help understand the essence of the problem. Code E1 or Er1 almost always means a malfunction of the temperature sensor (open or short circuit). The code Hi indicates that the temperature inside the chamber is high, and Lo indicates that it is too low.

Noisy operation or vibration may be associated with improper installation. The showcase must be strictly level. If the legs are unevenly twisted, the compressor may resonate with the housing. Also check whether the condenser tubes are touching walls or other objects.

If the compressor turns on too often (clocking), check the integrity of the door seals. A 1 millimeter gap allows a huge volume of warm, moist air to pass through, which instantly turns into ice on the evaporator. The compressor is working hard, trying to cool the incoming heat.

Why does the display case work, but does not cool after defrosting?

Most likely, the defrost cycle is broken or the drainage hole is clogged. Water from melting ice does not go into the tray, but freezes below, forming an ice plug. The defrosting heating element could also fail. Check whether water drips into the drainage tray during the defrost cycle.

Can a household refrigerator be used as a display case?

It is strictly not recommended. Household refrigerators are not designed for frequent opening of doors and constant load. Their compressor will quickly burn out, and the defrosting system will not cope with the amount of moisture coming from the sales area.

How often do the seals on the showcase doors need to be changed?

There is no set period, replacement is made as they wear out. If the rubber has become hard, cracked or no longer fits tightly (check with a sheet of paper), the seal needs to be changed. This usually happens once every 2-3 years of active operation.

What does the blinking number on the controller display mean?

Flashing usually indicates that a process is in progress (compressor operation, defrosting) or an alarm condition. For example, a flashing temperature often means that the current value is higher or lower than the specified alarm value.