Two heating element each of 220v 3.5 kw

Fig. 1 heating element is connected through one three-phase contactor with normally closed contacts MP (Fig. 1). It controls the TP thermostat starter, the control contacts of which are open when the temperature on the sensor is lower than the set one. When a three-phase voltage is applied, the contacts of the starters are closed and the heating element is heated, the heaters of which are switched on according to the "star" scheme.
Fig. 2 When the set temperature is reached, the thermal relay cuts off the power to the heaters. Thus, the simplest temperature controller is realized. For such a regulator, you can use the RT2K thermal relay (Fig. 2), and for the starter - a third-magnitude contactor with three groups for opening.

RT2K is a two-position (working on / off) thermal relay with a copper wire sensor with a temperature setting range from -40 to + 50 ° С. Of course, the use of a single thermal relay does not allow maintaining the required temperature accurately enough. Turning on all three sections of the heating element each time leads to unnecessary energy losses.

Fig. 3 If we realize the control of each section of the heater through a separate starter connected with its own thermal relay (Fig. 3), then it is possible to carry out a more accurate temperature maintenance. So, we have three starters, which are controlled by three thermal relays TP1, TP2, TP3. Response temperatures are selected, let's say as t1 elektronchic.ru

Purpose of heating elements

What are heating elements with thermostats for? On their basis, autonomous heating systems are designed, boilers and instantaneous water heaters are created. For example, heating elements are mounted directly into the batteries, as a result of which sections appear that can work independently, without a heating boiler. Some models are focused on the creation of anti-freezing systems - they maintain a low positive temperature, preventing freezing and subsequent rupture of pipes and batteries.

On the basis of heating elements, storage and instantaneous water heaters are created. The purchase of a boiler is not available for every person, so many assemble them on their own using separate components. By cutting a heating element with a thermostat into a suitable container, we will get an excellent storage-type water heater - the consumer will need to equip it with good thermal insulation and connect it to the water supply.

Heating elements for heating water with a thermostat are necessary not only to create water heating equipment, but also to repair it - if the heater is out of order, we buy a new one and change it. But before that, you need to understand the issues of choice.

Heating element selection

When choosing a heating element, you need to pay attention to some details. Only in this case, you can count on a good purchase, high-quality heating, durability and compatibility of the selected model with a water heating tank, boiler or heating battery.

Shape and size

Dozens of models of heating elements are presented for the choice of buyers. They have various shapes - straight, round, in the form of "eight" or "ears", double, triple and many others. When buying, you should focus on the use of the heater. Narrow and straight models are used for embedding in sections of radiators, since there is not enough space inside.When assembling a storage water heater, you should pay attention to the volume and shape of the tank, and on the basis of this, choose a suitable heating element. In principle, almost any model will work here.

If you need to replace the heating element in an already operating water heater, you must purchase an identical model - only in this case you can count on the fact that it will fit into the tank itself.

Power

If not everything, then a lot depends on the power. For example, this could be the heating rate. If you are assembling a small volume water heater, then the recommended power is 1.5 kW. The same heating element will be able to heat up disproportionately large volumes, only it will do it for a very long time - with a power of 2 kW, it can take 3.5 - 4 hours to heat 100-150 liters of water (not to boil, but on average by 40 degrees).

If you equip a water heater or a water tank with a powerful heating element of 5-7 kW, then the water will heat up very quickly. But another problem will arise - the home electrical network will not stand up. If the power of the connected equipment is higher than 2 kW, it is necessary to lay a separate line from the electrical panel.

Corrosion and scale protection

Choosing heating elements for heating water with a thermostat, we recommend that you pay attention to modern models equipped with protection against scale. Recently, models with an enamel coating began to appear on the market. It is she who protects the heaters from salt deposits. The warranty for such heating elements is 15 years. If there are no similar models in the store, then we recommend buying stainless steel electric heaters - they are more durable and reliable.

The presence of a thermostat

If you are assembling or repairing a boiler or want to equip a heating element with a heating element, choose a model with a built-in thermostat. It will save on electricity, turning on only when the water temperature drops below a predetermined mark. If there is no regulator, you will have to monitor the temperature yourself, turning the heating on or off - this is inconvenient, uneconomical and unsafe.

How to connect a heating element with a thermostat

Now you know how and by what parameters the heaters are selected. But how is the connection made? In order to connect a heating element with a thermostat, you must choose a wire with reliable insulation. We also pay attention to the cross-section - it must be such that the wire can provide full power to the heater and not melt. For example, for a 3 kW heater, the wire cross-section must be at least 2.5 mm. We recommend choosing cables with copper conductors for connection.

Two ways to connect the heating element to three phases.

"Three-phase" used to be something not very necessary and understandable for a common man in the street, but nowadays it has become a necessity for a private house. It is needed primarily for heating with electricity. Since an electric boiler has a large power (in most cases, more than 6 kW), when using one phase, you will need to lay the wiring with a cable with a large conductor cross section. And this will be expensive, especially if the cable conductors are made of copper. In a three-phase network, the cross-sections of the conductors will be noticeably smaller, for this reason, most modern electric boilers are connected to the "three-phase". Now let's talk about the basic schemes for connecting heating elements to such a network.

Star.

This method is used if the heating element is designed for 220 V. In addition, the "star" requires that a neutral wire be brought from the shield. For clarification, consider the following figure:

In this case, instead of two jumpers, there will be one. And it will be connected to zero, and the three remaining free ends will be connected to the corresponding phases. If you look at the block nut from above, then it will look like this:

Triangle.

This method is used to connect heating elements designed for 380 V. If you suddenly decide to put a "triangle" heating elements designed for 220 V, they will simply burn out. Don't miss this important point. The main difference between a "triangle" and a "star" is the absence of a neutral conductor. There are only 3 phases and nothing else. To better understand what is at stake, look below:

In the picture, everything looks simple and understandable, but if you start connecting the contacts on the block nut, you get the following:

It looks complicated, but in fact it does not differ in any way from the top picture. The colored lines and numbers here indicate the phases, and the letters indicate the heating elements of the block.

How it works and how to choose

The heating element with a built-in thermostat has a simple structure, consisting of two parts, a heating element and a temperature sensor connected to a temperature controller. But even here there are several features that significantly affect the serviceability and service life of the device.

The first thing to look at when buying is its case. A more durable heating element will be made of copper and have a corresponding noble color, the cheaper option is usually made of "acid-resistant stainless steel". There is no way to be sure how resistant this stainless steel really is in the store, so give preference to the brass version of the case. The outer diameter of the tube is usually 13 mm, but there are also thin, low-power options - 10 and even 8 mm each;

• Marking. Since we are considering a heating element for a water heater, you should make sure that in the marking, before the designation of the operating voltage of 220V, there is a letter "P", denoting work in water and weak alkaline solutions;
• Power. It should be borne in mind that when connecting to a regular home network, you should not use a heating element, more powerful than 2.5 kW - this gives too much load on ordinary wiring. If you plan to connect a more powerful heating element with a thermostat, lay a separate cable from the shield with the appropriate section to the place of its installation.
• The temperature sensor is located in a separate tube and, if necessary, is removed from it together with the thermostat. Evidu is a pivot. Inside contains a thermocouple, which, when heated, activates the thermostat mechanism. Often, the failure of the thermal sensor forces the heating element to turn off at low temperatures.

Scope of application.

Heating element with a thermostat is a universal device and is used as a heating element for:

1. Temporary electric heating organizations. For this, through a special fitting, it is inserted into a register or into a cast-iron battery;
2. Heated shower water. To do this, it is enough to have a container, in the case of which a hole is made next to the bottom, into which the heating element is inserted;

In general, a heating element with a thermostat is the cheapest source of heat and hot water at the installation stage. The cost of the device starts at $ 5 (2 kilowatt model Ariston), and a set of appropriate fittings (gasket and nut) will not cost more than $ 1.

Water heater device

The design of an electric heating element for heating or water heating is quite simple:

• body made of steel or plastic;
• it houses a stainless steel water tank;
• a heating element is installed in the tank.

According to the design of Ariston, the water ten is a spiral with a shell. This coil is taken and sealed with a dielectric powder with a certain packing, most often magnesium oxide. Therefore, the period of operation depends on the stability of the film and on the maximum set temperature. In current heating units, thermostats are certainly installed - devices that regulate the temperature, turn off the heating or turn on the heating elements, depending on the desired temperature.

Also thermostats can help you save a lot, since they do not allow the device to work in vain, if the required temperature is reached, therefore, heating the water to the set value, it turns off.If the joint work of water with electricity is performed, in this case, it is necessary to worry about a reliable security system, which is guaranteed by the regulator. In the event of problems or breakdowns, it turns off the heating system. In such water heating elements, there is the following order of work:

• the flow of cold water flows through the tube to the heating coil or through several such coils;
• then the thermostat regulates the water temperature;
• the outlet will have hot water of the required temperature.

disadvantages

In principle, the price of the device ends with all its advantages and the disadvantages begin:

1. Uneconomic. In principle, this is not a "disease" of the heating element itself, but rather of the devices that are assembled with its help. Most often these are artisanal heating registers and homemade water heaters. Both the first and the second do not provide at least some kind of energy conservation, therefore, the electricity bills will be obscenely huge;
2. Fragility. Due to the proximity of the thermocouple to the heating elements, the heating element with a built-in thermostat very often performs an on / off cycle, which negatively affects all automation and disables it after a maximum of 2 years of use. True, the positive side is that the automation changes without problems and the need to remove the thermal element;
3. Inability to accurately adjust the temperature. The knob on the thermostat gives a very rough idea of ​​what the outlet temperature will be. Again, the close proximity of the heat sensor and the heating coil makes accurate adjustment nearly impossible;
4. No moisture protection. Considering that such a heating element is often installed in a bathroom to provide hot water, you will have to take care of splash protection yourself and place it in such a place so that water does not get onto its body.

In general, a heating element with a thermostat solves two questions posed to it:

1. Security temporary heating
2. Security temporal hot water supply

We do not recommend using this device as a permanent heat source and preferring higher quality and more economical products.

Video.

An example of how heating elements can be used to organize very cheap heating.

Comments:

Stas

The device is the very thing if you need to quickly make an electric radiator from a conventional radiator. This design helped out many times. Instead of one bottom plug, such a device is screwed in and the battery is filled with water. All. electric battery ready

Denis

Stas, so it turns out not an electric radiator, but an energy eater. The efficiency tends to zero, and there is no heat transfer.

Stas

Denis, I don’t argue. I wrote it quickly. Those. when it comes not to a permanent connection, but to a temporary hut. For builders in a living room for the off-season, for example. You won't buy an electric convector for a month if the central heating is turned on in a month? And sitting in the cold is not an option either.

Denis

I do not know why the author did not like the stainless steel heating element - in my experience, both brass and stainless steel options serve the same

Leave a comment cancel reply

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Heating element device.

The heating element is an electric heating element made of a thin-walled metal tube (shell), the material for which is copper, brass, stainless and carbon steel.Inside the tube there is a nichrome wire spiral, which has a high specific electrical resistance. The ends of the spiral are connected to metal leads, which connect the heater to the supply voltage.

The spiral is insulated from the walls of the tube by a compressed electrically insulating filler, which serves to remove heat energy from the spiral and securely fixes it in the center of the tube along its entire length. Fused magnesium oxide, corundum or quartz sand is used as a filler. To protect the filler from moisture penetration from the environment, the ends of the heating element are sealed with a heat-and-moisture resistant varnish.

The heater leads are insulated from the tube walls and rigidly fixed with ceramic insulators. The supply wires are connected to the threaded ends of the terminals with nuts and washers.

The heating element works as follows: when an electric current passes along a spiral, it, heating up, heats up the filler and the walls of the tube, through which heat is radiated into the environment.

When heating gaseous media to increase heat transfer from heating elements, they are used ribbing

made of material with good thermal conductivity. As a rule, corrugated steel tape is used for ribbing, wound in a spiral onto the outer shell of the heating element.

The use of such a constructive solution helps to reduce the overall dimensions and current load of the heater.

Schemes for the inclusion of heating elements in a single-phase network.

Tubular electric heaters are designed for a specific value power

and
stresses , therefore, to ensure the nominal operating mode, they are connected to the supply network with the appropriate voltage. According to GOST 13268-88, heaters are manufactured for rated voltages:

12

24

36

42

48

60

127

220

380 V