Correct adjustment of the temperature regime in industrial refrigeration equipment is the foundation on which food safety and economic efficiency of the enterprise are built. Unlike their residential counterparts, where the process is often automated to the simple turn of a knob, professional cabinets and chambers require an accurate understanding of the operation of thermostats, controllers and refrigerant. An error in setting even by a couple of degrees can lead to damage to an entire batch of goods or, conversely, to excessive energy consumption due to excessive cooling.
The adjustment process depends on many factors: the type of installed automation, the specifics of the loaded product and the operating conditions of the room. Temperature range must be maintained stably, without sudden jumps that can damage the structure of the products. In this article we will analyze setting algorithms for various types of controllers, consider the nuances of working with evaporators and answer questions that often arise among technical personnel and business owners.
The importance of accurate calibration for different types of products
Each group of products requires strict compliance temperature conditions. Refrigerated meat and fish are typically stored at -2 to +2 degrees Celsius, while dairy products and prepared culinary products may require a range of 0 to +6 degrees Celsius. Incorrect settings lead to the proliferation of pathogenic microflora or, in the case of freezing, to the destruction of the cellular structure of the product by ice crystals.
Industrial refrigerators are often equipped with powerful compressors that quickly bring the chamber to mode, but the inertia of the system can cause overshoot. If you set the temperature on the controller too low, the evaporator will become covered with a fur coat, and the fan will begin to drive icy air, drying out the packaged goods. Air humidity inside the chamber also directly depends on the temperature difference between the evaporator and the product.
⚠️ Attention: When storing mixed product groups (for example, meat and vegetables in one chamber) it is necessary to focus on the requirements of the most sensitive product or use zoning if the cabinet design allows it.
Modern microprocessor controllers allow you to set not only the main temperature, but also defrost parameters, which is critical for maintaining product quality. Ignoring these settings leads to the fact that the sensors begin to show incorrect values, and the control system operates in emergency mode.
Types of temperature control systems in professional equipment
Before proceeding with setup, it is necessary to identify the type of installed control system. In the industrial sector, the most common are electronic controllers, such as Carel, Dixell, Danfoss or Emerson. These devices have a digital display and allow you to program complex operating algorithms, unlike old mechanical thermostats.
Mechanical thermostats, for example series TAM or K59, are adjusted by rotating a screw or knob inside the housing. They are less accurate, have large hysteresis (the difference between turning on and off) and often require periodic calibration or replacement. Electronic systems read readings from sensors with high accuracy and control the compressor through a relay.
- 🔹 Digital controllers: allow you to set exact values, have password protection, display the history of accidents.
- 🔹 Mechanical thermostats: easy to use, cheap, but subject to drift of readings over time.
- 🔹 Pneumatic systems: found in very old models, they work based on the expansion of gas in a bellows.
Understanding the type of control system you have is the first step to a successful setup. If the front panel has buttons and a digital display, you are likely looking at a microprocessor-based device. If only a rotary regulator with marks or a scale is visible, we are talking about mechanics, where the exact temperature can only be found using an external thermometer.
What is the difference between hysteresis and differential?
Hysteresis is the temperature difference between turning on and off the compressor. Differential is often used as a synonym, but in some controllers it is a separate parameter that determines the width of the sensor dead zone.
Algorithm for setting up electronic controllers (Dixell, Carel)
Setting up electronic controllers requires entering the parameters menu. The standard procedure looks like this: you need to hold down a certain combination of buttons (often these are arrow buttons or a special button Set) for 3-5 seconds until the parameter code appears. For example, for controllers Dixell this is often a button Setheld for more than 3 seconds.
After entering the menu you will see a flashing code, for example St (set point) or rS (switch-on temperature). Using the navigation buttons, change the value to the required value. It is important not to confuse the compressor set point and the defrost set point. After changing the value, you must confirm the input with the button Set or Enter.
☑️ Checklist for setting up the controller
There is also a hysteresis parameter, which is designated as Hy or dIF. It determines how many degrees the temperature must rise for the compressor to turn on again after being turned off. Too little hysteresis will lead to frequent engine starts, which will shorten its life, and too much will cause temperature fluctuations in the chamber.
⚠️ Attention: Controller manufacturers can update firmware and change menu logic. Always check the current technical documentation (manual) for a specific equipment model, since parameter designations may differ.
Adjusting mechanical thermostats
If your industrial refrigerator is equipped with a mechanical thermostat, the adjustment process looks different. The adjustment screw is usually hidden under a plastic cover or located inside the chamber on the side wall. Turning the screw clockwise, as a rule, reduces the temperature (makes it colder), and counterclockwise - increases it.
The main difficulty of the mechanics is the lack of digital display. You can't see exactly what the temperature is inside right now. Therefore, it is critical to use an external verified thermometer. Place it in the center of the chamber, next to the product (product simulator), and adjust in small steps, waiting for the readings to stabilize 20-30 minutes after each turn.
Mechanical thermostats of the series Danfoss or Orion have a scale, but it is often conditional. The numbers on the scale (1-7) do not correspond to degrees Celsius. For example, position "3" may mean +5°C in one chamber and 0°C in another, depending on the thermal insulation and load. Calibration such devices can only be done experimentally.
Table of recommended storage temperatures
To set it correctly, you need to clearly know what product you plan to store. Below is a reference table that will help you navigate the basic settings for various product categories. Remember that these values are averaged and may vary depending on the specific requirements of SanPiN or technological maps of your enterprise.
| Product type | Recommended temperature (°C) | Humidity (%) | Shelf life (days) |
|---|---|---|---|
| Chilled meat | -1... +2 | 85-90 | 3-5 |
| Chilled fish | -2... +1 | 85-90 | 2-3 |
| Dairy products | +2... +6 | 80-85 | 5-10 |
| Vegetables and fruits | +3... +8 | 90-95 | 10-30 |
| Ready cooking | +2... +6 | 75-80 | 1-2 |
Use of this table allows you to set initial settings, which can then be (corrected) depending on the actual state of the product. For example, if the meat begins to dry out, it may be worth raising the temperature a little or checking the operation of the evaporator.
Typical errors and troubleshooting
One of the most common mistakes is setting the defrost temperature higher than necessary. If the defrost parameter is set to, for example, +20°C, and the temperature in the chamber should be +4°C, the system may not start defrosting on time, which will lead to ice fouling on the evaporator. This, in turn, will worsen heat transfer and force the compressor to work without stopping.
Another mistake is ignoring the location of the sensor. The temperature sensor should be located in an area where air circulates, but should not touch the walls of the chamber or the product itself (unless it is a product sensor). Incorrect location leads to false readings and incorrect operation of the automation.
- 🔸 Frequent switching on: check the hysteresis and tightness of the door seals.
- 🔸 Insufficient cold: check the defrost settings and the presence of an ice coat on the evaporator.
- 🔸 Freezing: perhaps the sensor is shifted to the zone of direct blast of cold air from the fan.
It is also worth paying attention to the cleanliness of the condenser. If it is clogged with dust, the efficiency of the refrigeration machine decreases, and the set temperature may not be reached even with continuous operation of the compressor. Regular maintenance is the key to stable temperature conditions.
FAQ: Frequently asked questions
How often should you check the temperature in an industrial refrigerator?
At least twice a day (morning and evening) with data entered into a log. When loading a new batch or changing settings, monitoring should be hourly until the mode stabilizes.
What to do if the controller shows error E1 or E2?
These codes usually indicate a malfunction of the temperature sensor (open or short circuit). It is necessary to check the integrity of the wires and the contact of the sensor. If the sensor is working, the problem may be in the controller itself.
Is it possible to store meat and vegetables in the same chamber?
It is highly not recommended. Meat requires a temperature of about 0°C, and vegetables +4...+8°C. In addition, vegetables can absorb odors, and meat bacteria can contaminate plant products. Use separate cabinets.
Why does the refrigerator not turn off after setting the temperature?
Possible reasons: the set temperature has not been reached (primary cooling in progress), the chamber is leaking, the condenser is dirty, or the thermostat/controller is faulty. Also check if the fast freezing mode is turned on.