Design features of water heaters with dry heating elements, advantages and disadvantages of devices, classification of closed heating elements, cost of products.
A water heater with a dry heating element is an apparatus with heating elements that do not have direct contact with water. The well-thought-out design of the device ensures a long service life and reliability in operation. We will talk about the features of the functioning of a water heater with a dry heating element in this article.
The device of dry heating elements of water heaters
In the photo there are dry heating elements for a water heater
When buying an electric water heater, the user is faced with a huge range of devices. Products of various models are visually identical: the outer cases are cylindrical or in the form of a parallelepiped, there are control knobs, thermometers, temperature regulators and other required elements. The choice can be made correctly only if the internal structure of the device is known.
The type of heating element is of fundamental importance for a boiler. The efficiency of the device depends on its design., durability, power consumption, etc.
Today there are two types of heating elements - wet and dry. A traditional wet heater is a copper tube with a nichrome coil filled with insulating material. The cell is in the water in the storage tank of the device, therefore it is often called open.
Dry heating element diagram for a water heater
Relatively recently, boilers began to be equipped with heaters of a new type that do not come into direct contact with water. Such products are gradually replacing traditional boilers with wet heating elements from the market, despite their high cost. Their design is fundamentally different from traditional models.
Dry heating element of an electric water heater consists of three main parts:
- Spiral… Usually made from Rescal or Khantal wire, which has high resistance properties. When connected to the electrical network, it heats up to a temperature of 800 degrees. The power of the element, its dimensions and the consumed voltage depend on the cross-sectional area of the wire.
- The foundation… It is made of ceramic, it is made in the form of a cylinder. A spiral is wrapped around it. Various types of ceramics are used for the manufacture of the base, the main requirement for them is to keep their shape at a high temperature. It is clear that such a structure cannot be installed in water without protection. To protect the coil from liquid, a protective flask (casing) is used.
- Protective flask… It is welded to the inner tank and cannot be dismantled when disassembling the product. It looks like a blind pipe, the inner diameter of which is 2-3 mm larger than the diameter of the heating element. The gaps between the base and the casing are sometimes filled with a thermally conductive material. The pipe is made from ordinary steel with an enamel coating (as in the Thermor and Atlantic models) or stainless steel (in the Electrolux, Gorenje, Fagor, AEG, Tesy, Termal, Galmet, Ariston models).
Advantages and disadvantages of dry heaters
Photo of a water heater with a dry heating element
Closed models are more advanced heating devices compared to traditional wet products. They have a number of indisputable advantages, therefore, user reviews are always positive about water heaters with dry heating elements.
Advantages of the devices:
- Fast water heating… The dimensions of the heating elements are small, so several of them can be placed in the tank.Manufacturers have provided the ability to individually turn on a separate heater, which allows you to select the power of the device for each individual case. When all elements are turned on, the water will heat up in the shortest possible time.
- Interchangeability of parts… Many models of water heaters with dry heating elements have the same device and connection dimensions for the heaters, which makes it possible to use the same products for repairing different devices.
- Minimum salt deposits on the surface of the protective flask and the walls of the tank… Layers on the details, of course, appear over time, but in small quantities. The thickness and time of the appearance of the sludge depend on the hardness of the water and its temperature. The more salts in the liquid, the shorter the time between boiler repairs. The surface of the flask remains clean due to the absence of direct contact of the heating element with water. The working area of the heater is large enough, therefore, the protective casing does not heat up to high temperatures and does not provoke the formation of salts. In addition, the flasks are coated with an anti-corrosion compound that does not allow sediment to linger on the surface. Thanks to these qualities, the heating elements change 1 time in 4-5 years. It is impossible to completely refuse to replace or clean parts. Due to layers, the water heating rate decreases, the spiral overheats and burns out over time. In addition, the payment for power overruns will increase.
- Easy maintenance of dry heaters… Dismantling the work item can be done independently without the involvement of a wizard. There is no need to drain the water from the tank during the procedure. No consumables are needed for replacement, and from the tools you need only a screwdriver to get the job done.
- Temperature protection… Storage water heaters with dry heating elements cannot be turned on without water due to the presence of thermal protection blocks. If they are out of order, the repair of the device will consist only in replacing the burned out heaters.
- High reliability of dry heaters… Modern protective flasks are highly durable thanks to their enamel coating with special additives. Product life is increased by 28% compared to "wet" heaters.
- Operational safety… In the event of an emergency, electric shock is excluded.
Air congestion does not occur in boilers of this type, because the design of the device excludes the penetration of air masses into the tank. The absence of plugs extends the life of the product.
Water heaters with dry heating elements have a number of disadvantages that the user should be aware of:
- Ineconomic operation… The heating elements must first heat the flask, and then the heat is transferred to the water. But such losses can be neglected. The diameter of the heater is only 2-3 mm less than the inner diameter of the bulb, and very little heat is spent on the air gap.
- Dry models power… The indicator is less than that of wet ones (1, 2 kW versus 2 kW), but 2 parts are installed in the device at once, which in total exceeds the characteristics of the second option. In addition, if necessary, one element can be turned off and save energy.
- Price… The price of water heaters with dry heating elements is higher than that of wet models, but due to the numerous advantages, the increased price is justified.
Dry heating elements of water heaters must be handled very carefully so as not to damage. Do not clean them mechanically. Even sandpaper can cause them to malfunction. For this procedure, you can only use special chemicals, for example, citric acid.
How to choose a water heater with a dry heating element?
Dry heater circuit diagram
Every user dreams of buying the best dry-type water heater. To make the right choice, study the characteristics and operating conditions of the device in advance. First of all, pay attention to the type of dry heating element and the manufacturing company.
For the convenience of users, dry heating elements are divided into classes according to the filling of the free space between the base and the bulb:
- Flasks without filling… These are inexpensive elements of a simple design, inside of which, except for the base with a spiral, there is nothing. In such parts, some of the energy is spent in transferring heat to the enclosure. Users with any income can buy a water heater with a dry heating element with an air gap.
- Oil filling flasks… The option is more profitable than the first one due to minimal heat loss during heat transfer from the base to the bulb.
- Flasks filled with white sand… From operating experience, the last option is considered the most reliable. These heaters are durable and rarely burn out. Each type of such a heating element is suitable only for a specific model of a water heater, so when buying a device, immediately purchase spare parts for it.
Classification of dry heating elements for water heaters depending on the base material:
- Rod heating elements… These are thin and straight products that are installed in tanks with a volume of at least 50 liters. Their dimensions are standardized, so the elements can be installed in water heaters from various manufacturers. Up to 3 elements can fit in a metal bulb, but due to their small diameter, their total heat transfer does not exceed the heat transfer of one wet heater.
- Steatite heating elements… The base of the product is made of steatite, a heat-resistant material based on a special type of ceramic (magnesium silicate), from which ovens are made. It is an artificial insulating material obtained from talc processing. The base is in the form of a cylinder, in which longitudinal and transverse grooves for the nichrome spiral are provided. The presence of steatite heaters in the boiler can be identified by the presence of the word "Steatite" in their name. Since 2012, Atlantic and Thermor have been equipping their models with such elements.
Both options are very popular, therefore, it is possible to decide which water heater with a dry heating element is better only after studying the operating conditions of the device for a specific case.
The choice can also be influenced by the undoubted advantages of steatite heaters:
- They differ from previous models by their large diameter and the presence of a ribbed surface, which increases the heat transfer area. Therefore, the water heats up much faster.
- The material has unique properties: it is very durable, has greater mechanical stability, does not burn, does not lose shape at a temperature of 1000 degrees, and is not susceptible to stray currents.
- The ceramic ribbed core of the base heats up slowly and cools down slowly, which allows heat to be released even after the device is turned off.
- Steatite dry heating elements for water heaters last much longer than products of a similar purpose.
- In devices with such elements, there is no copper-steel pair, which leads to the appearance of an electrochemical reaction and destruction of the enamel coating on the surface of the tank.
Among the shortcomings, one can single out the lack of interchangeability of steatite parts. They are made for specific models of dry heaters and are not universal. In addition, products are more expensive than rod models.