Many users mistakenly believe that a refrigerator is a device solely for cooling, so the presence of a heating element there is puzzling. Indeed, at first glance it seems absurd to heat the air in a chamber that is supposed to freeze food. However, the presence Heating element (Tubular Electric Heater) is a critical condition for the operation of modern automatic defrosting systems.
Without this small but powerful component, your No Frost would turn into a solid ice monolith after just a couple of weeks of active operation. The heater turns on at strictly defined moments, when the compressor is resting, and performs a highly specialized task of removing moisture, which inevitably condenses on the evaporator.
In this article we will analyze in detail the physical principles of the system, explain why ice blocks air circulation, and show how exactly cyclic heating extends the life of the entire unit. Understanding this process will help you better navigate the symptoms of malfunctions and not panic when you hear strange sounds or see water under the drawers.
The basic operating principle of the No Frost system
System No Frost (literally “without frost”) is fundamentally different from older models with drip defrosting in that it forces air through the chambers. The fan drives air masses through a special heat exchanger, where they are cooled and then distributed throughout the volume of the refrigerator. During this cooling process, moisture from the air settles on the cold walls of the evaporator in the form of frost.
If this frost were not removed, it would gradually increase its mass, turning into a dense ice coat. The critical threshold is considered to be a layer of ice more than 3-5 mm thick, which begins to work as a heat insulator, interfering with the effective removal of heat, and at the same time narrows the channels for the passage of air. This is where the heating element comes into play.
The frequency of turning on the heater depends on the model and electronics settings, but usually this happens every 8-12 hours of compressor operation. At this moment, the fan stops, the compressor turns off, and the heating element begins to heat the surface of the evaporator, melting the accumulated ice.
- ❄️ The evaporator cools the air, taking moisture from it.
- 💧 Water freezes on the fins of the heat exchanger, forming frost.
- 🔥 The heating element turns on according to a timer and melts the ice crust.
- 🌊 Melt water flows into a special tray for evaporation.
⚠️ Attention: If you notice that there is noticeably less space in the freezer or food has begun to freeze to the walls, this is a sure sign that the defrosting system (including the heating element) is not working correctly.
Types of heating elements in refrigeration equipment
Not all heaters are the same, and manufacturers use different designs depending on the layout of the refrigerator and its price segment. Most often found open heating element in the form of a curved metal tube, which is mounted directly under or above the evaporator. Its efficiency is high, but it is more susceptible to corrosion from constant contact with water.
In more modern and expensive models, such as Liebherr or Siemens, sealed heaters are used, sealed in an aluminum case or even embedded directly into the structure evaporator. Such elements last longer, since they are protected from direct contact with an aggressive environment, but their replacement requires disassembling most of the unit.
There are also heaters built into the drainage system. They do not heat the evaporator itself, but only prevent water from freezing in the outlet channel. This is important because even if the ice on the evaporator melts, it can freeze again in the narrow drain tube, creating a blockage.
The choice of heater type affects the maintainability of the device. Open spiral heating elements are easy to replace yourself if you have access to the back wall, while integrated systems require qualified intervention and often replacement of the entire evaporator assembly.
Algorithm for starting defrost and the role of the thermostat
The defrosting process is not just turning on the heater on a schedule, it is a complex chain of events controlled by electronics or mechanical timer. First, the control unit gives a command to stop the compressor and fan. Only after this is voltage applied to The evaporator heating element.
The key element here is the defrost thermostat (or temperature sensor). Its job is to prevent the heater from working too long. As soon as the ice melts and the temperature on the evaporator rises to a certain value (usually about +10...+15°C), the thermostat opens the circuit, turning off the heating element.
After turning off the heating, a pause begins, which is necessary for the condensate to drain. Only after making sure that the temperature has dropped (or after waiting a fixed time), the controller starts the compressor again to cool the chambers. Malfunction of any link in this chain leads to malfunctions.
☑️ Symptoms of defrosting malfunction
It is important to understand that the heating element does not heat constantly. Its total operating time per day is only 30–40 minutes, divided into several cycles. This time is enough to remove moisture, but not enough to significantly heat the food in the chamber, since the process occurs locally, in a hidden compartment.
Diagnostics of heater malfunctions
When the heating element burns out, the refrigerator does not stop freezing instantly, but the efficiency of its operation drops catastrophically. The first sign is a “crying” evaporator, which is covered with snow. The fan continues to blow air, but due to the ice plug it does not enter the chamber, but circulates inside the technical compartment.
To check the integrity of the heater with a multimeter, you need to gain access to the evaporator. On models Indesit or Atlant this often requires removing the back panel of the freezer. The continuity test of the circuit should show a resistance in the range of 200–400 Ohms (the value depends on the power of the heating element).
If the device shows a break (one on the screen or an arrow pointing to infinity), the element must be replaced. It is also worth checking the defrost thermostat and fuse, which often comes in conjunction with the heater and burns out when overheated.
| Symptom | Probable cause | Action |
|---|---|---|
| Ice on only one side | Failure of one of the heating element circuits | Replacing the heater |
| Water inside the chamber | Drainage clogged or drainage heating element burned out | Cleaning or replacement |
| Refrigerator does not turn off | Heat transfer is impaired due to ice | Checking the defrost system |
| Crackling noise is heard during operation | Thermal expansion of heating element parts | Normal (if not loud) |
⚠️ Attention: Before any diagnostics, be sure to disconnect the refrigerator from the power supply! Working with electrical appliances under voltage is deadly.
The influence of heating elements on energy consumption
There is a myth that the presence of a heater in the refrigerator significantly increases electricity bills. In practice, the share of energy consumed by the heating element is no more than 5–7% of the total consumption of the unit. The main part of the energy is “eaten” by the compressor, which is forced to work harder if the defrosting system cannot cope.
The paradox is that a working heating element saves electricity. If the ice is not removed, the compressor must run almost non-stop trying to break through the icy insulation. In this mode, energy consumption can increase by 20–30%.
Is it possible to operate a refrigerator with a burnt-out heating element?
Theoretically, it is possible if you regularly (once every 1-2 weeks) defrost the refrigerator manually for 24 hours. However, constant wear and tear of the compressor will quickly lead to its breakdown, which will cost much more than replacing a cheap heating element.
Modern inverter models have learned to manage this process even more efficiently, turning on heating only when humidity sensors detect critical fouling, and not according to a strict timer. This makes them even more economical.
Replacing a heating element: is it worth doing it yourself
Replacing a burnt-out heater is one of the most common repair operations. In simple models it takes 30–40 minutes. However, the difficulty lies not in the heating element itself, but in access to it. It is often necessary to dismantle shelves, drawers, a fan and plastic covering.
When installing a new element, it is important to ensure tight contact and correctly secure the temperature sensors. Poor assembly can lead to the heating element heating the plastic parts, causing them to melt and the appearance of an unpleasant odor.
If you are not confident in your abilities, it is better to entrust this work to professionals, especially if the refrigerator is under warranty. Independent intervention in a sealed circuit (although the heating element does not directly relate to it) can be regarded by the service as a violation of operating conditions.
Frequently asked questions (FAQ)
Why does the heating element turn on when it should be cold in the refrigerator?
The heating element is turned on in a hidden technical compartment, separated from the main chamber by thermal insulation and partitions. When the fan is running, the fan is stopped, so heat does not reach the food. A short heating cycle (15-20 minutes) does not have time to warm up the main volume of the chamber.
Can a heating element cause a fire?
If it works properly and is installed correctly, no. The defrost thermostat strictly controls the temperature. The danger arises only when installing an abnormal heater of higher power or when the thermostat malfunctions, when the heating element heats constantly.
How often should you check the operation of the heating element?
There is no need to specifically check it. The indicator is the absence of ice in the freezer. If you see that the back wall is overgrown with a “fur coat,” it means that the defrosting system (heating element, timer or sensor) requires diagnostics.
Does the heating element hum during operation?
The heating element itself is silent. However, as the metal tube heats up and cools down, it may make a characteristic cracking or clicking sound due to thermal expansion. This is a normal physical process that does not require repair.