Electric heating elements: main types, principle of operation and installation features
Features of choosing an electric heating element
Recently, electric heaters have become a familiar accessory for both residents of high-rise apartments and owners of country cottages. This equipment provides residents with the necessary amount of water that is required for domestic use. Electric heating elements for water heaters are the main structural elements of any device, it is due to them that water is heated.
- Types of structures
- open views
- Closed Options
- Connection methods
- Parallel connection
- Series connection
- Combined method
- Possible malfunctions
- Popular manufacturers
- Ariston Products
- domestic products
- Boilers Electrolux
Types of structures
Structurally, the heating element is a tubular electric heater. The heating element of the heating element can be made of high carbon steel, stainless steel or copper.
In each of these tubes, which is a kind of shell, there is a wire spiral. It is used to conduct electricity.
According to the principle of operation, all heating elements can be divided into two main types. In one case, heating elements are made in the traditional form — almost the same as in a conventional electric kettle. «Wet» devices are called due to the fact that the element is in contact with heated water. And when the equipment is closed, the tube is in a special flask that heats the liquid. The element thus does not come into contact with water, which is why this type is called «dry».
To find out which heating elements are best used for boilers, you need to briefly familiarize yourself with their main design differences.
A characteristic feature of these elements is that they are located in direct contact with water heated in a storage tank. The tubes are filled with quartz sand, which is a good thermal conductor. The main element of such a heating element is a thin nichrome wire in the form of a spiral.
Most often, copper or stainless steel is used in the manufacture.
Open heating elements are divided into groups according to certain technical characteristics:
- Absence or presence of an anode nest. If the heating element is equipped with a nut, then it may not have an anode fastening or, in addition, a fastening thread is located on the flange.
- Taking into account the method of fastening, heating elements are nut and flange. In this case, the latter can be made by casting or stamping.
- The shape of open heating elements can be straight or curved. The shape depends on the type of storage tank for heating water.
Heating elements for boilers quickly heat up the liquid, in addition, they are notable for their low price. But the disadvantages of such devices are much more. The main disadvantages are:
- high level of danger;
- the rapid appearance of plaque (especially given the quality of water in the central highways);
- high power consumption;
- short service life.
This is a special type of heating element, which is insulated with a ceramic flask. This flask has strict requirements for strength. During the manufacture of the flask, magnesium silicate or steatite is used, while the heating element itself in this case is made of stainless steel.
That is why the water in a closed type boiler is heated by the heat transfer of the casing.
There are several advantages in this case. First of all, due to the closed design, these devices are absolutely safe, since the possibility of a short circuit is completely excluded. In addition, such types of heating elements:
- easy to operate;
- easily repaired;
- have a fairly long working time;
The flange, as well as the drive itself, in these water heaters is protected with an enamel coating that prevents the appearance of scale. It is for this reason that the operating time of «dry» elements is approximately 3 times longer compared to «wet» ones.
On the negative side, it can be noted that all steatite heaters are not universal. They are made separately for any type of boiler, and it should be borne in mind that, if necessary, the element should only be replaced with a similar one.
It should be noted that heating elements for boilers can be mounted in the device either one at a time or several at once.
The more heaters, the higher the power of the equipment. But the power indicator will also depend on how all the elements are connected to each other — this connection can be single- and three-phase.
This connection option must meet certain requirements.
The basic rules are as follows:
- The voltage both in the electrical network and in each individual element must be the same.
- To determine the total power of the boiler, you need to sum up the power of all installed elements.
- If for some reason one of the heating elements breaks, the circuit will continue to work. In this case, the only thing that needs to be done is to change the broken element.
To find out the total power of the mains, you need to divide the voltage by the total resistance of the network. And the total resistance can be determined by the formula that is applied during the parallel connection of individual resistances.
The second option is to connect in series. Wherein following operating principles must be followed:
- If one of the heating elements breaks down, the operation of the entire network will be interrupted.
- To find out the total resistance, it is necessary to sum all the resistances in the network.
- The total voltage cannot be greater than the total voltage of all heating elements.
Given this scheme, different connection options must be used in several sections of the electrical circuit. Quite often, the combined method is advisable if it is impossible to purchase heating elements of the required power. In this case, available heating elements are installed, and the required value is achieved using various connection methods.
According to experts, the period of operation of heating elements in boilers is approximately 5 years. The most common cause of equipment failure is hard water. To prolong the service life of the device, regular preventive maintenance is needed, which consists in cleaning the anode and directly the heating element from scale that has appeared.
The main sign that the heating element is broken is the lack of heating and the operation of automatic protection. There are several options for checking an element for its functionality:
- With a simple light bulb. To do this, you need to assemble a serial network, which consists of a light bulb and a heating element connected to electricity. If the light is on, then everything is in order with the heating element and it is not necessary to replace it.
- Using a tester, you need to determine the resistance of the heating element. If the resistance is zero, then the heating element must be changed.
Replacement of elements must be carried out with devices that fully correspond to the capacity of the boiler. The steps in this case are:
- First you need to turn off the power and water supply. After that, the liquid is drained from the storage tank and the top cover of the device is removed.
- After that, you need to check the input terminals with a phase meter for the absence of current.
- The bolts that fix the heating element directly are unscrewed, then the wiring cable is removed.
- It is imperative to determine the state of the contacts of the new heating element. They must be dry.
- Then, simultaneously with the heating element, the anode is also replaced, which is designed for protection.
- During the installation of a new element, only high quality seals are used without any defects.
- Installation is carried out in the same way, but in reverse order.
- At the end, the storage tank must be filled with water, and the remaining air must be released from the tap, which is designed to supply hot water. After that, it remains only to connect the water heater to the mains and check it for operability.
To date, heating elements are presented on the domestic market in a fairly large assortment, while there is a huge selection of different manufacturers. All devices differ both in their design and in their main purpose and average market price.
This is an Italian manufacturer that manufactures heating elements from a special alloy of chromium-nickel and copper. The heat output of the equipment is increased by using a special brass flange. Approximate power will depend on the specific model and is in the range of 1-6 kW.
Models of heating elements with an installed thermostat enable the consumer to independently set the required temperature (not more than +95°C). When this indicator is reached, the device automatically turns off. If the temperature drops by more than 7-8 degrees, the heating element resumes its work, so the water in the storage tank will be constantly hot.
Termex has been known on the market for over 60 years. Magnesium anodes of this company are made of a special alloy, due to which the performance of the elements is doubled. The outer sheath can be either copper or stainless steel. With the help of reliable protection, a long time of operation is ensured. All devices are low-power, due to which they are quite economical.
The company from Switzerland is characterized by the excellent quality of manufactured water heaters. Its products are distinguished by the fact that they are equipped simultaneously with two closed heating elements. This results in a high heating rate. Protective measures prevent scale formation. These measures include:
- thermostat that turns off the equipment when it reaches +80°С;
- special vitreous enamel coating;
- protection against moisture and dust;
- magnesium anode;
- storage tank thermal insulation.
There are advantages and disadvantages to water heaters with heating elements of both “wet” and “dry” types. It is more reliable to buy equipment with a “dry” heating element, since it is characterized by a long operating time, the device does not depend on water quality and is resistant to corrosion.
It is not necessary to choose premium devices, you can purchase devices from a lesser-known manufacturer. The most important thing is to regularly inspect the heaters and diagnose problems in a timely manner.