Modern household appliances are becoming more and more complex, acquiring new functions and protection systems that are often hidden from the user’s eyes. When we talk about dishwashers, many people think of just a container with sprayers where they need to put dirty dishes. However, a complex physical process takes place inside this metal box, requiring precise control of temperature conditions.
The central element in this heating system is instantaneous water heater, which is often confused with a regular heating element in a tank. This device is responsible for instantly heating water to the specified parameters immediately at the moment it passes through the system. Understanding how this unit works will help you better operate the equipment and diagnose faults in a timely manner.
In this article we will analyze in detail the design of the heating element, its differences from storage systems and the reasons why manufacturers had to implement just such a scheme. You will learn why the temperature of the water entering the machine can be cold, but inside the chamber it reaches 70 degrees.
What is an instantaneous water heater and where is it located?
Instantaneous water heater, or duct, is a sealed flask with a heating element inside. Unlike older models of washing machines, where the heating element was immersed directly in the water of the tank, dishwashers use a closed circuit. Water from the water supply enters this heater, quickly warms up and is supplied under pressure to the sprinklers.
The location of this unit is usually located at the bottom of the machine body, often combined with a circulation pump and filtration system. This arrangement allows you to minimize heat loss, since the path of hot water to the nozzles takes a few centimeters. The design is made of stainless steel or special heat-resistant plastics that can withstand high pressure.
The key feature is the absence of a large volume of water inside the heater itself. This eliminates the formation of scale on a large scale, which is typical for boilers. Power Such elements usually vary from 1.5 to 2.5 kW, which allows the water flow to be heated almost instantly.
To extend the life of the dishwasher, use special salts for dishwashers, even if the water in your region seems soft.
It is important to note that in different brand models Bosch, Siemens or Electrolux the design may differ in shape, but the principle of operation remains the same. The machine's electronics strictly control the outlet temperature, regulating the energy supply to the coil.
Operating principle and difference from storage systems
The basic principle of operation is heat exchange between a powerful electrical element and a flowing fluid stream. When you start the program, the pump pumps water, the flow sensor signals the controller, and only after that voltage is applied to heater. This ensures that the element will not burn without water.
In storage systems, which are extremely rare in modern dishwashers, it would take time to warm up a large volume of liquid in the tank. The flow system does not have this disadvantage. The water is heated on the fly, which saves cycle time and energy, since there is no need to maintain the temperature of a large volume of water for an hour.
The heating process is cyclical: water passes through the heater, washes the dishes, drains, is filtered and again enters the flow channel for reheating. Thus, during one washing cycle, the same portion of water can be heated dozens of times, maintaining a stable temperature.
Why can't you turn on the machine without water?
A dry start of a flow-through heater will lead to its instant burnout, since heat removal does not occur, and the temperature of the coil will reach critical values in a fraction of a second.
Why do you need heating if the tap water is hot?
Many users wonder: why overpay for electricity if water flows from a hot tap at a temperature of 50-60 degrees? The answer lies in the hygiene requirements and chemistry of the washing process. For effective breakdown of fats and activation of enzymes in modern tablets, a temperature of at least 65-70 degrees.
Tap water rarely reaches such values consistently. In addition, hot water from the central pipeline often contains more impurities and hardness salts, which form scale faster. By using cold water and heating it inside the machine, you get water of ideal quality for a specific program.
There are also programs with low-temperature washing (for example, for glass) or, conversely, with high-temperature disinfection (75°C), which cannot be implemented by relying only on the temperature of the water supply. The electronics of the machine itself decides to how many degrees the flow needs to be heated at the moment.
Using cold water at the inlet also prolongs the life of the plastic elements of the machine's structure, which could deform faster if they were in constant contact with boiling water.
Main faults and signs of breakdown
Like any electromechanical unit, a flow heater is subject to wear. The most common problem is education scale on the walls and spiral, which impairs heat transfer. As a result, the machine runs longer, trying to reach the desired temperature, or even shuts down by mistake.
The second common cause of failure is an insulation breakdown or a burnt-out spiral. In this case, the machine can start the program, draw water, but the wash will take place in cold water. The dishes will remain dirty, and a white coating from undissolved powder will appear on the glass.
The following symptoms may indicate a breakdown:
- ⚡ The machine hums, water is drawn, but after a while the program is interrupted with an error code.
- 💧 Dishes remain cold and damp after the “Intensive” cycle.
- 🔌 Protection circuit breakers in the electrical panel are triggered immediately when heating begins.
- 👕 The appearance of a characteristic smell of burning or burning plastic during operation.
Diagnostics should be carried out using a multimeter, checking the resistance between the contacts of the heating element. The normal resistance for a working 2 kW element is about 25-30 Ohms.
☑️ Diagnosis of heating problems
Heater characteristics comparison table
To better understand the differences between the types of heating elements used in household appliances, consider the comparison table. It will help you evaluate the benefits of a flow-through system specifically in the context of dishwashers.
| Characteristics | Instantaneous heater (Dishwashers) | Cumulative heating element (Washing machines) | Geyser |
|---|---|---|---|
| Operating principle | Heating water flow on the go | Heating a static volume of water | Heating the flow through a heat exchanger |
| Heating rate | Instant (seconds) | Long (minutes) | Instant |
| Risk of scale | Medium (depends on hardness) | High (air contact) | High (depends on water) |
| Energy efficiency | High (no storage losses) | Medium (tank cooling) | High |
The table shows that the flow system is most effective for cyclic processes where rapid temperature changes are required. That's why it has become a standard in the dishwasher industry.
How to extend the life of a heating element
Service life ductus directly depends on the quality of the water and proper operation. Hard water is the main enemy of any heater. Calcium and magnesium salts settle on the spiral, creating an insulating layer that causes the element to work with overload.
Use regenerating salt specifically designed for dishwashers. It restores the operation of the built-in water softener, which protects not only the dishes, but also the internal components of the machine. Check the salt level in the tank regularly, even if you use 3-in-1 or 5-in-1 tablets - they often do not contain enough salt for hard water.
Once every 3-4 months, it is recommended to run a wash cycle using a special dishwasher cleaner. Such products contain active components that dissolve fatty deposits and light plaque inside the system.
⚠️ Attention: Never use regular table salt or hand washing detergent in the dishwasher. This will lead to corrosion of the tank and rapid failure of the flow heater.
It is also important to keep the filters at the bottom of the chamber clean. If they are clogged with food debris, water circulation is disrupted, which can lead to local overheating of water in the heater area.
Regular use of special salts and cleaners increases the service life of the heater by 1.5-2 times, preventing costly repairs.
Frequently asked questions (FAQ)
Is it possible to connect the dishwasher to hot water only?
Technically this is possible if the water temperature does not exceed 60 degrees, but manufacturers do not recommend it. This disrupts the program as the machine will not be able to rinse off the powder with cold water at the beginning of the cycle or reduce the temperature for delicate modes.
Why did the machine stop heating water after replacing the heater?
In modern models Bosch, Candy and others often require a software error reset or temperature sensor calibration. Without this, the controller may block the supply of voltage to the new heating element, considering the system faulty.
You hear a crackling sound when heating up - is this normal?
Slight cracking or clicking noises may be caused by thermal expansion of materials or air bubbles passing through the heater. However, a loud hum or hiss may indicate an insulation breakdown or severe scale buildup that requires element replacement.
What is the electricity consumption of a flow-through heater?
The consumption depends on the duration of the heating phase. During one standard washing cycle, a dishwasher consumes from 0.8 to 1.5 kWh of electricity, and 90% of this energy is spent on operating the instantaneous water heater.