Water heaters with a dry heater and a stainless tank: operating principle and device diagram

According to experts, water heaters with a dry heating element and a stainless tank appeared on the domestic market quite recently, this happened about 10 years ago. Despite its low popularity, the device in question is of considerable interest to many users. In our article we will describe the design of the water heater, the advantages and disadvantages over a standard boiler with a wet heating element. Let's take a closer look at several popular models of such boilers.

Advantages over traditional “wet” heating element

In terms of external features, the device in question is no different from a standard boiler. The same body, made in the form of a cylinder or parallelepiped, the presence of a temperature regulator and a thermometer with a scale. In modern models, the operation of the water heater can be monitored on a liquid crystal display.

Important: the main advantage of a water heater equipped with a dry heating element is a long period of operation, as well as the formation of a minimum amount of scale during operation.

If the heating elements in a conventional boiler are changed every two years, then dry heating elements are replaced with new ones every four years of operation . Despite the second advantage - a small layer of scale on the heated surface, the formation of this substance will depend on the quality of the water entering the container, as well as the operating temperature of the heater.

Types of heating elements in water heaters

Thus, conventional heating elements made from stainless steel or copper have a high temperature in small areas of the working surface, which will contribute to the accumulation of salts. Due to the formation of scale on the surface of the heating element, the water warms up worse, and heat transfer rates decrease. The accumulated sediment does not conduct heat well, which will ultimately contribute to the burnout of the coil and further replacement of the heating element.

The working surface area of a dry heater is much larger than that of its analogue, but it does not heat up as much, which can be achieved by adjusting the device. Lower water temperatures will help reduce the amount of deposited scale, which means our boiler will last longer without the need to replace the heating element. If a dry heating element burns out, it is much easier to replace it than a traditional one.

Please note: When replacing a dry heater, there is no need to drain the water heater. In this case, you just need to remove the heating element from the special flask and replace it with a new one.

Flaws

Since ideal things do not exist in nature, dry heating elements also have negative sides. True, there are not so many of them.

A dry heating element can be exclusively straight. Therefore, they are used in models with a volume of at least 30 liters. So if you need to purchase a “baby” one of 10–20 liters, this option will not work.

But the main disadvantage of a dry heating element is its high cost. Models equipped with such a heating element usually cost no less than one and a half times more than traditional water heaters with a “boiler”. Whether such a unit is worth the money spent on it, everyone must decide for themselves.

Device

If we briefly describe the internal structure of the device, there are also few differences - a heating element is installed in a stainless steel tank protected by heat-resistant enamel. There is also a magnesium anode present in the inlet and outlet piping.

Diagram of a water heater with a dry heating element

When familiarizing yourself in detail with the internal structure of the device being described, you need to pay attention to the design of the heating element - this part is slightly different from a conventional spiral. The heating element is a ceramic product. Nichrome or tungsten spirals are installed in special recesses, which supply heat. The ends of these threads pass through the mounting flange and are secured with studs.

The entire structure of the heating element is located inside a special flask treated with protective heat-resistant enamel. Having examined the design of the boiler, you can understand why the heating element is considered dry. The fact is that such a heater does not have direct contact with water , but there is one small problem here. The flask and heating element are made of different metals that interact with each other, and this is a direct path to electrochemical corrosion. The first destruction usually occurs in the weakest metal, the tank - even a protective layer of heat-resistant enamel cannot save it.

Important: To reduce the harmful effects of corrosion, a magnesium anode was included in the design of the water heater. During the interaction of metals, this element is destroyed instead of the walls of the tank.

In most cases, dry heating elements are placed in a steel flask, which is similar to the material of the tank. In this situation, there should be no galvanic couple. This is where a completely fair question arises: why do we need a magnesium anode if the possibility of corrosion is completely excluded? According to numerous observations, slight corrosion of metals occurs, but the anode can take on this negative impact, which will ultimately increase the service life of the device.

Advantages

Compared to open “boilers”, dry structures have many advantages. For example, let's look at just a few of them:

No scale on the heating element

The rate of formation of this unpleasant layer is affected by the quality of the water and the surface area of contact between the heater and the liquid. The harder the water in your area, the faster scale will form. A thick lime layer reduces the quality of water heating, and the operating life of the heating element is reduced.

The dry heating element is protected from such trouble. In this case, direct contact with water does not occur. This means there is no scale on the heater either.

Compact dimensions

A dry heating element is relatively small in size and takes up much less space than its “wet” counterpart. Thus, the size of the storage tank itself is reduced. Most often, manufacturers install two or even three heaters in one device. This allows the consumer to independently regulate the load. If you need to quickly heat a large volume of water, turn on all the heating elements at once and you will get hot water in just a few minutes.

Even if one of the heaters burns out, nothing bad will happen. During the repair period, you will simply use one of the remaining ones and will still be left with hot water.

Excellent performance

This is another advantage of dry heating elements. Since there is practically no scale formation on such a heater, the speed of obtaining hot water increases significantly. In this case, much less electricity is consumed than when heating water with a “wet” heating element.

By itself, each dry heating element installed in a boiler most often has a lower power than a similar option with a “wet” element. But since water heaters of this type usually use several heating elements, the total power will be significantly lower than that of a “wet” tubular heater. And the consumer can decide whether to use it in full or partially.

TOP 3 best water heaters with dry heating elements Timberk

Timberk SWH FED1 80 V
Timberk SWH RE15 50 V
Timberk SWH RED1 100 V

Reviews on Yandex.Market

Ease of maintenance

Water heaters with a dry tubular element have one important feature. They are designed in such a way that if the heating element suddenly fails, you don’t even have to drain the water from the tank to replace it. It is enough to unscrew the protective flange, remove the element, inspect or repair it and insert it back.

Long service life

Due to the lack of contact with scale, dry heating elements have a long service life. One such element is enough for an average of 5 years of uninterrupted operation. While boilers with conventional heating elements fail once every 2-3 years. At current prices for components, this allows you to save a lot.

Dry start protection available

Absolutely all models with a dry heater are equipped with a protection system against switching on without water. If there is no water in the heater tank, the system simply will not allow the unit to turn on. Dry start protection will prevent the tubular heater from burning out. Even if for some reason it does not work, the failure will only affect the heating element. Other boiler systems will not be affected.

Variability

Many dry heating elements have a completely identical design. This allows the same element to be used for different tank models. So in case of repair, you will not have problems with components.

No problems with air locks

Water heaters equipped with dry heating elements are not at risk of developing internal air locks.
For models with “wet” heaters, this can result in expensive repairs. See also -
Choosing a long-burning solid fuel boiler: rating of the 10 best boilers

Gorenje GBFU E B6 for 100, 80 and 50 liters

The water heater in question is designed for specific consumer needs. The volume of the water tank can be 50, 80 or 100 liters. Depending on this, the price of the device also changes. The boiler is connected to a 220 volt power supply and has a power of 2 kilowatts. To protect the product from the negative effects of corrosion, one magnesium anode is provided.

The advantages of Gorenje GBFU E B6 for 100, 80 and 50 liters are:

small need for electricity to heat water;
affordable price;
ease of installation;
reliability;
fast heating of water (up to 3 hours after filling the entire volume with cold liquid).

The main disadvantage of this boiler is the error in the thermometer readings.

How to determine the volume of the internal tank of a water heater

Electric water heaters with a capacity of 5, 10, 15 liters are suitable for washing hands and dishes, usually installed above or below the sink. 30-liter - for taking a shower in dachas, etc. They are easy to install and economical. Designed for an average family of three people. Electric water heaters with a capacity of 50, 80, 100, 120, 150 liters are suitable for large families. Electric water heaters with a capacity of 200 and 300 liters are suitable for autonomous hot water supply to the private sector.

Electrolux EWH 80SL

This boiler has two dry heating elements placed in a special flask to prevent contact with water. To prevent destruction of the heating element, a magnesium anode of the “protect tank” type is provided. The device is connected to a 220-watt power supply and has a power of 1.8 kW. The tank capacity is 80 liters.

The reservoir with the heated liquid is protected from cooling by special thermal insulation. The water heater has a temperature sensor and a thermostat that allows you to set the required level of water heating (from 30 to 70 degrees).

The advantages of Electrolux EWH 80 SL are:

long period of operation;
ease of installation;
holds the temperature for a long time (according to some users, up to 3 days without turning on the heating elements);
fast water heating;
absence of noise when heating elements operate;
low energy consumption.

The disadvantages include the high cost and significant dimensions of the device.

Principle of operation

Dry heat boilers are in demand due to their functionality, as well as the speed of heating to the desired temperature. If the electric heater is not hidden in the shell, it comes into contact with hard water, and over time, limescale and scale will form on it. This increases the heating time. In a dry heating element, the rod is hidden, so scale does not hinder its operation.

The operating principle of the heating element located inside the tank:

The valve opens and the tank is filled with water to a certain level.
When the water is inside, the heating element turns on, bringing it to the temperature that is set in the installations.
After heating, the heating element automatically turns off.
When the water is not used immediately, the insulation around the tank keeps it hot.

Electrolux EWH 50 Formax DL

An electric water heater equipped with two dry heating elements with a power of 0.8 and 1.2 kW, which makes it possible to regulate a wide temperature range. This modern device is equipped with a digital display and has many useful functions, for example, three-mode temperature control. Water heating range from 30 to 75 degrees.

According to experts, the optimal operating temperature for Electrolux EWH 50 Formax DL is considered to be 55 degrees, which will protect the heating elements from overheating and minimize the possibility of scale formation. The working container is protected from hypothermia by a 22 mm layer of polyurethane.

Boiler advantages:

compact dimensions;
long-term maintenance of operating temperature;
the ability to use heating elements in three modes;
beautiful appearance;
fast water heating;
acceptable cost.

There are no deficiencies found in the Electrolux EWH 50 Formax DL.

TOP 10 boilers with dry heat

The rating included only the best devices that received a large number of positive user reviews.

ARISTON BLU1 ECO ABS PW 65 V SLIM

Electric storage water heater with several water intake points. Electronic control, connects to a standard outlet. The tank capacity is 65 liters, the internal coating is titanium enamel. Has protection against switching on without liquid. Additional options include accelerated heating. Installation – wall-mounted, vertical. Maximum pressure – 8 atmospheres. Heats water to a temperature of 80.

Pros:

stylish design;
compact dimensions;
simple controls;
ease of connection;
high efficiency;
long warranty period.

Minuses:

Touch controls don't always work the first time.

Atlantic STEATITE 80 N3

Atlantic water heaters with dry heaters are high-quality devices with high performance with minimal energy consumption. They have a spacious tank, which allows the model to be used even for a large family. The product’s steatine heating element is located in a special way, thanks to which the device provides users with hot water much faster than analogues. The magnesium anode protects the device from rust formation.

Pros:

stylish design;
compact dimensions;
spacious tank;
high efficiency;
low power consumption;
maintains temperature for a long time;
does not make noise;
long operating time.

Minuses:

an uninformative thermometer on the tank that shows inaccurate data.

Gorenje TG80EBB6

Electric storage water heaters with a dry heater Gorenje TG80EBB6 are powerful devices with mechanical control. There is a thermometer on the body that shows the temperature of the water in the tank. The model has a mode that prevents freezing, protection against overheating, and against switching on without water. Fixed on the wall in a vertical position.

Pros:

good quality of materials and workmanship;
affordable price;
spacious tank;
high water heating speed;
Ease of Management;
protective functions;
stylish design.

Minuses:

none.

Thermex ERD 50 V

Water heaters with a 50-liter dry heater Thermex ERD 50 V are high-quality devices that quickly heat water to a temperature of 75. The model has a convenient mechanical control and a thermometer on the body. It is characterized by high efficiency and low energy consumption. Works stably for a long time.

Pros:

heats water quickly;
maintains temperature for a long time;
ease of maintenance;
long operational period;
does not degrade the quality of the liquid;
quiet operation;
low power consumption.

Minuses:

an inconvenient thermometer without numbers, so it is difficult to determine the water temperature.

Electrolux EWH 80 Formax

The Electrolux water heater with dry heater is a device with convenient mechanical control. Allows you to regulate operation not by temperature, but by watts, so you can select the optimal heating mode for energy consumption. It has reliable protection against overheating and turning on the device when the tank is empty. Can be installed both vertically and horizontally.

Pros:

convenient control;
compact dimensions;
different installation options;
fast heating;
informative guide;
powerful;
consumes little electricity;
clear settings.

Minuses:

soft metal body;
Inappropriate fasteners included.

Atlantic Vertigo Steatite 100 Wi-Fi

A flat water heater with a dry heater, which is characterized by its compact size and high efficiency. Quickly heats water up to 70. Control from a smartphone is provided. The model is equipped with a thermometer and an informative display. The spacious tank has an internal enamel coating. Has a frost prevention mode and an accelerated heating function. Can be installed vertically and horizontally.

Pros:

intelligent mode – you can set the liquid heating time;
ability to connect to a smart home system;
clear, informative display;
control from a smartphone;
spacious tank;
compact dimensions;
stylish design;
energy efficiency;
high performance.

Minuses:

high price.

Gorenje GBFU 80 B6

80 liter dry heater water heater, which is characterized by high performance and energy efficiency. Recommended for use in rooms with cold water supply. Provides hot water to several points at once. This allows you to use the device immediately to obtain hot water in the bathroom and kitchen. The model has convenient mechanical control. Equipped with a safety valve against freezing and overheating protection.

Pros:

precise work without any complaints;
long operational period;
spacious tank;
high-quality fasteners included;
ease of installation;
clear controls;
functionality.

Minuses:

Poor quality tap for water connection.

Vogel Flug PVD504820/2h

Water heaters with a dry heater and a stainless tank Vogel Flug PVD504820/2h are high-quality devices with high performance. The model has convenient mechanical control. There is an informative thermometer on the body that provides reliable readings. The tank is coated with titanium enamel, which does not change the quality of the water. Has a heating limitation option. The overheat protection function is well implemented. The device is mounted only in a vertical position.

Pros:

high quality;
fast heating;
long warranty period;
convenient control;
environmental friendliness;
does not degrade the quality of the liquid;
limited heating option;
good protective functions;
ease of installation.

Minuses:

difficult to find on sale.

Which company should you choose?

On forums dedicated to the selection of household appliances and specifically water heaters, users recommend choosing the following brands: “Ariston” (Italy), “Ballu” (China), “Electrolux” (Sweden), “Zanussi” (Italy), etc. Devices from these companies are distinguished by high productivity, durability and safety in terms of operation.

Nuances of choice

Choosing a water heater is a responsible process for each user, since it should last up to 10 years. It starts with determining the volume of the device.

To calculate the tank, you can contact specialists who will perform an accurate calculation of water use for hot water supply based on the volume of consumption for a specific family.

You can also use the advice and choose the following options for your household needs:

15-liter - enough for washing dishes, they are usually installed in the kitchen;
30-liter - suitable for a shower with one user;
50 liters, capable of providing water use via hot water supply for a family of 2 people;
80-liter, provides water use via hot water supply for a family of 3 people;
100 liters, guarantees supply for a family of 4 people.

Often for large families it is more efficient to install two devices instead of one, separately for the bathroom and kitchen.

When choosing a dry heating boiler, it is recommended to pay attention to the following parameters:

The heating element is made of stainless steel or ceramics. Ceramic heaters cool much more slowly and do not create extraneous noise.
The number of heating elements is better than two, since high-quality regulation is ensured and there is a power reserve in the event of failure of one of them.
The control unit must have a thermostat, a temperature sensor, a power board and a display.
Warranty conditions, during which the manufacturer undertakes to repair the water heater free of charge.