Electric heating elements have not changed their design for decades and remain in demand in heating equipment. The shape and materials of these devices change, but the principle of operation and efficiency remains the same. Information about differences and characteristics will be helpful for a competent selection. Do you agree?
You will learn what heating elements for heating are and how they work. We have described in detail the varieties of heating elements, led indisputable arguments for a reasonable choice of the optimal type. With our recommendations, you will purchase the required device without mistakes.
Content of the article:
- Purpose of heating heaters
- The internal structure of electric heaters
- The principle of operation of heating elements
- The types of heating elements for heating devices
- Tubular models for domestic
- Ribbed version of electric heaters
- Block design of heating elements
- Cartridge type appliances
- Additional functions of electric heaters
- How to choose a heating element for the heating equipment?
- Calculation of the appliance power
- Consider the design
- Length of the heating tube
- Additional functions
- Conclusions and a useful video on the topic
The purpose of the heating elements
Electric heaters have gained popularity due to their versatility and high efficiency. All the electricity they consume is used for its direct purpose - to heat the environment.
Main heating appliances where TENs are used are:
- Remote and stationary electric oil heaters.
- Water heating radiators.
- Bathroom heaters.
- Electric fireplaces.
- Electric convectors.
- Electric boilers.
The above equipment can be used as the main or additional heating source. It is inexpensive, easy to install and requires no special skills in operation.
With a cast iron central heating radiator, the heating element can be connected after disconnecting the common riser. Such a device can be used for primary and supplementary heating
The internal construction of electric heaters
It is convenient to consider the construction using the tubular model as an example. The electric heater is a thermal conductor-filled ceramic or metal tube with a coil inside. Where the tube is fixed to the flange there are insulating sleeves that make it impossible for the conductive coil to contact the body of the heating element.
Most models of electric heaters use similar components, but their durability may vary depending on the quality of assembly
The electric heater is mainly fixed by a flange connection, which allows the internal environment of the heater to be sealed from the external space. The disadvantage of this design is that the coil cannot be replaced if it burns out internally.
The principle of operation of heating elements
The heating element works according to the following principle. When connected to the mains, the internal coil is heated and the energy is transferred to the thermal conductor and the outer sheath. The heat is then transferred to the surrounding liquid, air or solid material.
When a heating element immersed in oil or water, convection currents are created around the tube, which mix the heat transfer medium and contribute to its even heating.
Electric boilers are known for their reliability and maintainability. They do not have many complicated parts, so they are easy to operate and maintain
Liquid-free heaters usually have limited heating temperatures to avoid damaging surrounding parts or causing a fire.They often use a fan to speed up heat exchange by allowing air to circulate both inside the appliance and in the surrounding room.
Technology heater types
Simplicity of heating elements does not always turn out to be user-friendly. Many manufacturers produce electric heaters with specific shapes and attachments. In case of a breakdown, it is quite difficult to buy them in the store. Therefore, in order to make the right choice, it is necessary to study all possible design options.
Tubular models for domestic heating
The tubular design of electric heaters is the most common in mobile oil heaters, portable and wall mounted electric radiators. Heat transfer in them can be by: convection, infrared radiation or conduction.
Fabricated heaters with a regulator and their own power cord can only be purchased if you are sure that the wire length is sufficient
The tube shape and length in such devices can be anything and is only dictated by design features. For example, the heating element of a micatremic heater is a coil located behind a mineral plate.
The most common characteristics are:
- diameter - 5-18mm;
- length - 200-6000mm;
- shell material - steel, stainless steel, ceramic, copper;
- power - 0.3-2.5 kW.
Heater output of more than 2.5 kW is not used in domestic heating appliances because domestic wiring simply cannot withstand the higher load.
Ribbed version of electric heaters
Ribbed devices are a modification of the tubular heating elements. Their peculiarity is the many thin steel plates arranged along the entire length of the device. This design dramatically increases the contact area with the environment ensuring a high heating rate.
Ribbed TENs are more expensive and require more space, but provide a higher consumer performance of the heating equipment
The ribbed models are mainly used in air heating heaters. They allow a rapid increase in room temperature, especially when equipped with an integrated fan.
Block design of heaters
Block type consists of several tubular heaters combined in a single mount.
Particular attention must be paid to the capacity of the block heating elements and to the heat dissipation capacity of the boiler with pump
This design is used when two factors combine:
- Higher power requirement of the unit and higher heating rate of the medium.
- Unable to quickly transfer the heat energy from the coil to the environment due to the small area of the outer shell.
Factually, a block heating element reduces the load on each heating tube and increases the rate of heat transfer. Such devices are included in household heating boilers and industrial electric heating units.
The capacity of the block models can be 5-10 kW, therefore when placing them in an apartment it is required to pull an additional electric cable into the room.
Cartridge type TENs have the form of a tube with one free end, due to their installation feature. The outer shell is usually made of polished steel to allow maximum contact with the surrounding material. Such tubes are inserted tightly into a suitable hole in the heater.
The main disadvantage of cartridge heaters is the small heat emitting surface area, which requires specific means of heat removal
The cartridge models are fixed mainly by means of a flange connection. They are typically used in industry for heating the working parts of extruders.
There are other structural types of TENs but these are mainly used in industrial production and do not deal with the subject matter under discussion.
Advanced functions of electric heaters
The simplest designs of appliances that do not have any built-in regulating mechanisms have been considered above.
Thermostatic control unit may have mechanical or electronic automatics. The latter is more precise but demanding on the parameters of the home power supply
But electric water heaters can be equipped with simple automatics providing the unit with additional functions.
- Thermostatic regulation. Heating elements with built-in thermostat for heating have a temperature sensor which is triggered when the medium heats up to a certain level. The electric heater is adjusted from the outside of the flange.
- Antifreeze. This function is provided by a simplified thermostat which is activated only when the temperature drops to 0-2°C. It prevents the water in the heating pipes from freezing by consuming a minimum of electricity.
- Turbo heatingwhich provides forced heating of the operating medium during the initial start-up. It must be remembered that the room wiring must be able to withstand a short-term increase in power.
Turbo heaters supporting additional functions are not many, because often the whole heater is regulated by a separate automation unit.
How to choose a heating element for a heating appliance?
When choosing a heating element to replace a water heater or radiator, you must pay attention to its power, construction, tube length and availability of additional features. That is why it is important to know as much as possible about all its characteristics before making the purchase.
Calculation of the heater power
Higher heat output is not always a good thing.
When choosing, it is important to consider several factors that are related to the power level:
- the heat output limit of the heater in general;
- wiring capacity;
- room volume.
Do not buy a device with a capacity that is greater than 75% of the heating equipment's maximum heat output.
For example, you have a radiator with 10 sections, each giving 150 watts of heat to the air, a total of 1.5 kW. By installing a 2 kW electric heater in it, the surface of the radiator will not be able to release all of the energy generated quickly. As a result, the heating element will constantly shut off due to overheating.
The reason for the quick breakdown of the heating element may be the wrong choice of the appliance power. As a result of system overheating, the coil will burn out over time
In apartments with worn-out wiring, the constant load on the socket should not exceed 1.5-2 kW, otherwise it could catch fire and lead to unfortunate consequences. Therefore before buying a heating element it is necessary to check the state of the wiring and, if necessary, remove the old and lay a new electrical network.
When the question of electrical and equipment possibilities is solved, you can start calculating the required power to maintain a comfortable room temperature.
In well insulated houses and apartments a 40 W/m will be enough. And if there are gaps in the windows, the heating power should be increased to 60-80 W/m3. Buy a particular model only after considering all the energy factors described above.
Consideration of design features
Most heating elements have a shell of alloy steel, which provides strength and resistance to corrosion. Copper devices are used predominantly in water heaters, although there are no restrictions on their use in makeshift radiators.
In cast iron and steel radiators, the use of nonferrous metal FETs is undesirable. This can lead to accelerated wear of materials and connections
Also, when selecting, consider the direction of the plug thread, which may be right or left. Different models of electric heaters also have different flange diameters. They can range in size from 0.5 to 1.25 inches.
Overly, a good manufacturer's heating element comes with a brief manual that describes its design parameters. A study of these will help to buy a device that exactly fits the existing heating equipment.
Length of the heating tube
The length of the tube is one of the main characteristics that determine the efficiency of the device.
Higher length for equal power leads to a larger surface area of the electric heater and faster heat exchange with the working medium. This has a positive effect on the lifetime of the heating element and the circulation rate of the heating medium.
Long tube heaters are ideal for installation in self-made registers, which are convenient for heating large rooms and outbuildings
It is advisable that the tube runs the whole length of the heater working area, not reaching the opposite wall by 6-10 cm. This recommendation will allow the heating medium to heat quickly and evenly.
It is not always necessary to overpay for additional features of the heaters. If the heater is used as an auxiliary heater and does not have its own built-in automatics, it makes sense to buy a model with a thermostat.
But if the radiator or electric convector has its own temperature sensors and temperature control mechanisms, the additional functions will remain unneeded.
The electronics built into the heating element plug should have safety mechanisms so that if the control board fails, there is no fire
It is therefore recommended to purchase expensive electric heaters with integrated automatics only if there is a clear need for such equipment. If there is a need for an indivudal selection of the temperature background, it is better to buy a thermostat in the socket, which can be used periodically.
As for the producers of heating elements, their choice is not crucial. The main suppliers are companies from Russia, Ukraine, Turkey and Italy. The quality of their products is about the same, so there is no point in overpaying for the brand.
Conclusions and useful videos on the topic
Video #1. A practical overview of different types of heaters:
Video #2. An overview of a thermostatically-controlled heating element:
Video #3. Features of the block heating element used in electric heating boilers:
Buying a heating element for heating appliances is not an easy task. It requires a clear knowledge of the characteristics of the equipment in which the electric heater is embedded. So stop your choice on a particular model only after a thorough analysis of its parameters.
Please write comments, ask questions, publish pictures on the subject of the article in the block below. Tell us about how you picked up the heating element for replacement in your electric boiler or mobile heater. Share what was the decisive factor for you personally in your choice.