Thermostat for a boiler - thermal relay: temperature control, types. Electronic thermostat for a boiler How does a thermometer work on a boiler

The thermostat for a water heater plays the same important role as a fuse in any electrical network. The user sets the required water temperature in the water heater, and the thermostat maintains it. That is, it allows the heating element to work until the water temperature reaches a predetermined value.

Then the heating element stops working. The water temperature drops (forced or natural) and the thermostat again gives a signal to the heating element to begin its direct duties.

Separate, specially designed types of thermostats have an additional function - to turn off the power supply to the heating element in the event of a breakdown of the latter. This avoids the possibility of electric shock, which is often the case with ungrounded boilers.

Types of thermostats

To date, many types of thermostats have been developed, but if we talk about devices specifically for boilers, then the most successful are three:

Rod. Such a thermostat is represented by a tube of small diameter (usually up to 10 mm) and short length (no more than 35 cm). The principle of operation is based on the elementary laws of physics: when heated, the tube expands linearly, which allows you to press the switch. Such thermostats have long been the most common in boilers. However, their accuracy left much to be desired - when leaving the hot water heater, the incoming cold water instantly cooled the thermostat due to the proximity of the latter to the cold water supply. Thus, the boiler could work beyond the allotted time, and this significantly affected the financial costs.
Capillary. A more advanced type of thermostat, also working according to the laws of physics. The tube containing the temperature-sensitive liquid bottle is usually made of a material that does not oxidize for a long time. Inside the balloon is a liquid that has a different density from water. When heated, the density of the liquid changes, the volume changes accordingly, and the liquid presses on a special membrane, which turns off the power. Such thermostats are more accurate when compared with rod ones. The deviation in temperature is approximately 3°C.
Electronic. More modern type and, accordingly, more accurate. It usually works in tandem with a protective relay - if the boiler is empty when voltage is applied to the heating element, then the protection will work, which will turn off the power.

According to another classification, all thermostats can be divided into:

Electromechanical and electronic. The first type works due to bimetallic elements, the second - thanks to special electronic sensors.
Simple and programmable. In the first type, the temperature is set manually mechanically. The second type is more precise in its work.
Overhead and mortise. For boilers, the invoice type is most often used, if the control is electronic, and mortise, if the control is mechanical.

Another interesting option is thermostats, which are designed for indirect heating boilers. Such boilers allow you to heat water using only the power for the heater, which means there are significant savings. But the liquid circulating in the heating system cannot heat up above the set mark, while the consumer may need a different temperature for the boiler (and most often it happens). In this case, you should buy a specially designed thermostat for this.

After carefully studying the articles on self-production, you can try to make a thermostat on your own.

Malfunctions and their solutions

The thermostat for the water heater may fail. Unfortunately, such phenomena are not uncommon, but there is nothing fatal here either. Firstly, as a rule, there is no repair - a thermostat that has worked faithfully is thrown away and a new one is bought. Buy the same or with a different resistance - the choice is up to the consumer. Secondly, with proper operation of the water heater, thermostat failure can be avoided or, in extreme cases, significantly extend its life.

How does a consumer notice a broken thermostat? As a rule, this is the most common way - the water is not heated in the boiler. In this case, either the heating element may be faulty, or the thermostat itself may be faulty, or (more rarely) both may be faulty. To check the latter, its resistance should be measured.

If during the check the picture on the display of the test device has not changed, you need to buy a new thermostat. This is not such a big money, so there is no need to grieve. Another option for testing a thermostat is possible: measuring the resistance when the thermostat itself is heated. If even then the test device does not show any changes - that's it, now just go to the store.

How to choose

Usually a faulty thermostat can be replaced with a similar one in form and principle of operation. However, if it is possible to buy and install another thermostat and there is an urgent need for this, then why not. The main thing is to be able to choose the right device and install it correctly. Although even here the Internet or a consultant at the point of sale can help the consumer.

But we should not forget: any independent actions without certain knowledge and strict adherence to safety rules can lead to a very unpleasant outcome.

It would seem that the heating element or volume should be important in the boiler, but, as it turned out, the thermostat and its role cannot be neglected. By setting the desired temperature and protecting the boiler from overheating, the thermostat is extremely important in the operation of the heater.

It can be used both for heating (as part of a radiator) and for providing a home with hot water. The first thing to do when putting it into operation is to protect the system from a possible breakdown of the electric heater, as well as create conditions for its autonomous operation. A popular method for solving this problem is to use a thermostat for a heating element. This small device, also called a thermostat, will help solve many problems.

Composition of water heating equipment

The simplest water heating or heating element should consist of at least three elements - a water tank, a heating element - a heating element, and a thermostat. The tubular heater can be submersible and dry. In the first case, it is made of stainless steel and placed inside the tank. Heating of water occurs at direct contact of water with TENOM.

Dry heating elements are made of ceramic, located outside the water tank. Heating of the coolant occurs due to the transfer of thermal energy through the tank wall. Such elements are easy to replace in case of failure.

The thermostat for the heating element is designed to control and maintain the set temperature of the coolant, as well as for emergency shutdown of the tubular electric heater from the network if the boiling process begins (as a rule, this happens when the heating element breaks down).

There are several types of thermostats, each of which is advisable to use with a certain type of tubular electric heating element.

Basic principles of work

Regardless of the design and execution, all thermostats operate according to the same scheme. For operation, the thermostat must be built into the tank, and also connected to the heating element. The whole process of temperature control can be divided into 4 stages:

The toggle switch sets the required temperature range of the coolant.
The thermostat for a heating element with a programmed mode measures the degree of water heating and gives a command to turn on the device.
When the water temperature reaches the set upper heating limit, the thermostat opens the electrical circuit and turns off the heating element.
After the water cools down, the whole process is repeated.

It is worth noting that no matter what temperature range you set, the thermostat will turn off the heating element if the water begins to boil. This is necessary to prevent damage to the heating equipment.

During boiling, the process of intensive vaporization begins. As the amount of steam increases, so does the pressure inside the tank. As soon as the pressure value exceeds the critical level, the tank will explode. The thermostat for the heating element does not allow this to happen, opening the electrical circuit in advance.

Types of thermostats

The principle of operation of the device always remains the same. Only the principle of determining the temperature of the coolant depends on the type of thermostat. According to this, all thermostats are usually divided into rod, capillary and electronic.

Rod devices, as the name implies, have the shape of a rod with a length of 25 to 50 cm. The principle of determining the temperature is based on the difference in the coefficient of specific thermal expansion of the two metals. The rod thermostat is installed outside the water tank in a special tube.

The capillary thermostat of a heating element for heating water is a hollow tube, inside of which a special liquid is “sharpened”. As the temperature rises, it expands, begins to put pressure on the walls and act on the membrane, which opens the circuit. On cooling, the reverse process occurs.

The operation of electronic thermostats is based on the ability of materials to change their ohmic resistance with a change in temperature. As a result, the voltage in the device increases or decreases, which is registered by special sensors and turn off or turn on the heating element. Electronic instruments are the most complex and expensive, but at the same time the most accurate.

Heating elements with built-in thermostats

The heating element separately from the thermostat is rarely used in practice. As a rule, such a solution has proven itself only in water-heating boilers. with a thermostat are much more common.

In such "combined" devices, the thermostat is located in a separate tube, and it is easy to replace it if it breaks. When choosing devices in this category, you need to pay attention to the following points:

Housing material. It can be represented by "stainless steel" (the cheapest and most common devices), as well as copper. Copper appliances last longer, but also cost an order of magnitude more expensive.
Power. For a home electrical network, it is dangerous to choose devices more powerful than 2.5 kW - there is a risk of overload and short circuit. When using more powerful heating elements, lay a separate power cable.

When choosing for a battery, you should not focus on expensive models. Practice shows that the durability of devices does not depend on the price. The service life is determined by the hardness of the water, the loads and the stability of the electrical network.

Spheres of application of heating elements with a thermostat

The scope of application of a heating element with a built-in thermostat is rather narrow, due to high energy consumption and short service life. They are most widely used in water heating equipment. Such a "water tank" is installed in the shower room or in the kitchen and serves as the main or backup source of hot water.

Very rarely tubular electric heaters are used for space heating. In this case, the element is installed directly into the radiator through a special fitting. The main advantages of installing a heating element with a thermostat in a heating battery are speed. With the help of such a simple solution, you can very quickly provide a house with a backup source of heat.

Features of heating elements for cast iron batteries

Tubular electric heaters for conventional and cast-iron radiators are practically no different. The only exception is the plug material - it must be made of cast iron or an equally heat-resistant material.

In addition, the shape of the outer part of the housing where the thermostat is installed may also differ. In this case, the length of the heating element should be 5-10 cm shorter than the length of the radiator. Otherwise, water circulation and heating cannot be achieved. Therefore, before buying, make sure that the heating element with a thermostat for cast iron batteries is intended.

thermostats on the market

Thermostats for heating elements can be called consumables. That is why it often goes separately from the heating element. To replace it, you just need to pick up a similar device on the market. To do this, find out:

Dimensions, type and method of fixing the failed device in the tank.
The maximum current that the new thermostat will have to handle.

The best option would be to buy the same device that has become unusable. This can be done by contacting the store with a faulty thermostat. In most cases, the sellers themselves will select the necessary device for you.

The thermostat for a water heater is a fairly important part. It is he who is responsible for maintaining a certain temperature at a constant level. The thermostat for the water heater is capable of slowly adjusting the temperature, and it is also equipped with a device that protects it from cooling and overheating. If necessary, it turns on and off the type, that is, the heating element.

This device gives the user the ability to set a certain mode of operation, and also maintains the temperature level in automatic mode. If the water temperature drops, it turns on the heating element, due to which the temperature rises to a certain predetermined level.

The thermostat for a water heater has a certain principle of operation. It is worth saying that it is similar for all types of water heaters. On the screw, which is equipped with each thermostat, a certain required water temperature is set. When the drain valve is screwed on, hot and cold water begins to flow into the mixer system, then the adjustment process starts. The temperature of the water is measured in the chamber, after which warm water is mixed with cold water in the required proportions. When supplying mixing water, hot water has an advantage, so it will flow until its temperature is above the set value. After that, the process of mixing it with cold water will start. Thanks to this fact, it can be explained that the thermostat for the water heater does not react so quickly. However, the user usually does not experience much inconvenience.

If the temperature controller for the water heater is installed in a system where there is no circulation of warm water, then cold water may enter the incoming stream at the initial stage. In systems where there is circulation of warm water, the thermostat adjusts the desired temperature in an instant.

Accumulative and flow units are usually supplied with different heating elements. Typically, heating elements in flow models have a higher power. That is why the choice should be made only after you decide on its purpose.

An electric thermostat may have a normally closed or normally open bakelite. Often owners of water heaters decide on independent repairs. The thermostat for the water heater "Ariston" and other companies is an electrical part, so it is worth remembering that different guarantees are given for the tank itself and for it. If you need to replace any element of the water heater or repair it, you should contact the service center or directly to the manufacturer, where you can find out if it is subject to warranty repair. It is important that the appropriate model of thermostat is available.

If you are interested in where you can buy this device when yours is out of order, then it is worth noting that most companies involved in the production of such equipment provide delivery throughout the country. For example, you can order a thermostat for a Termex water heater at home. It is easy to replace it yourself, using simple recommendations.

At the moment, one of the current purchases for the home is the purchase of a water heater (boiler) for water, which is explained by the huge popularity of autonomous heating and hot water supply.

The prerequisites for this process were the increase in the cost of centralized hot water supply and the ability of people not to depend on the hot water supply schedule, which is especially important in the summer in our country.

Purchasing a water heater is not as easy as it might seem at first glance. Buying a boiler requires accuracy and care so that the device can serve effectively and for as long as possible, without giving the owners much trouble.

Types of thermostats

The boiler itself is quite simple. You can install and connect the device even with your own hands. But when choosing a unit, you need to pay attention to which thermostat is installed in it. For example, if there is no temperature control in it or there is none. Exists several types of thermostats, on the basis of which water heaters are divided into several types:

Programmable or simple. This affects temperature control.
Electromechanical or electronic. The control of the device depends on this.
Mortise or invoice. The installation of the unit depends on this.

Most often found rod, electronic and capillary thermal switches. Rod models are obsolete and are a tube 35 cm long and 1 mm wide. Their working principle is as follows. When exposed to high temperature, the tube expands in size, which causes switch pressure. The disadvantage of this model is its inaccuracy. Due to the fact that the tube cools down too quickly, the boiler runs longer than necessary.

The principle of operation of the capillary thermostat is more modernized. A capillary thermostat is a tube containing cylinders filled with a liquid that differs in density from water.

With an increase in temperature, the liquid filling the cylinders of the capillary thermostat increases in volume and starts to put pressure on the membrane and the switch. The discrepancy error is 3 degrees.

Electronic thermostats are the most common models and the most accurate. The advantage of this model is in direct interaction with the protection relay. Due to its presence, an emergency automatic power off is carried out in the event of a lack of liquid in the tank.

Thermostat for water heater

The thermostat ensures the safe operation of the water heater. This process is explained as follows: when the temperature of the water rises, the pressure inside the tank rises, which is sealed.

When the pressure increase is not controlled, then the entire construction will explode, which is dangerous not only for equipment and surrounding objects, but also for human health, if a person is nearby during the explosion.

The thermostat allows you to keep the temperature at the desired level. Bottom line: temperature controller protects against explosion, overheating, damage to equipment and property, ensures the safety of people.

Most manufacturers try to equip the boiler with a thermostat, because it is he who controls water heating at the moment when the device is connected, and for the timely blocking of the heating element.

Presented on the market wide range of models but they all work in the same way. At the moment when it is necessary to connect the device to the network, you must immediately adjust the level of water heating, which is done using the control panel, which is located on the case.

Next, you should adjust the heating of the water. The relay that is installed on the thermostat will be responsible for opening the contacts of the heating element. When the tank is completely cool, the temperature will drop, it will become less than normal. In this moment contacts will close The heating element of the relay, due to which the system will start again and the liquid in the tank will again begin to heat up.

Replacing and connecting a thermostat for a boiler

In the event that the water heater does not work, then it should not be restarted. If it does not start, then the unit is not working! And you should not expect a sudden inclusion from him, you need to check for problems. If it is determined that the problem lies in the thermostat, then it must be replaced. The main thing is the ability to choose the right device and install it correctly. Internet resources and consultants in a store or market will help to deal with this issue.

To replace the thermostat, you must perform the following manipulations:

disconnect the boiler from the power supply;
shut off the water supply to the tank with a special valve;
drain all the water from the tank that is there;
remove the bottom panel of the device, this will allow you to get to the heating element;
remove the clamping ring located on the heating element;
get the sensor in the thermostat and the control unit;
install a new regulator;
return the clamping ring to the heating element;
reinstall the bottom panel of the device.

To purchase the required new thermostat for the boiler, you must follow the recommendations of experts. Going to a point of sale to buy a regulator, you need to take the technical passport of the device with you. With it, it will be much easier for the sales assistant to find out which model and with what characteristics you should choose.

When purchasing a thermostat yourself, you must remember that it must be the same model, which was before. Even the smallest difference can lead to damage to the entire water heater. It is necessary to buy a thermostat taking into account the type of product, parameters, installation methods, what working current and functionality it has.

Common thermostat problems

Any device, even the most reliable and expensive, fails over time, which is facilitated by a variety of factors, both internal and external. Breakdowns that require close attention:

If you do not have knowledge and skills in working with thermostats, connecting them, then it is better entrust this issue to specialists. This will, on the one hand, relieve you of unnecessary doubts and worries, on the other hand, ensure the correct operation of the unit and the safety of others.

It looks like a device for adjusting the temperature of water heating and for emergency shutdown

Then the heating element stops working. The water temperature drops (forced or natural) and the thermostat again gives a signal to the heating element to begin its direct duties.

Types of thermostats

To date, many types of thermostats have been developed, but if we talk about devices specifically for boilers, then the most successful are three:

Rod. Such a thermostat is represented by a tube of small diameter (usually up to 10 mm) and short length (no more than 35 cm). The principle of operation is based on the elementary laws of physics: when heated, the tube expands linearly, which allows you to press the switch. Such thermostats have long been the most common in boilers. However, their accuracy left much to be desired - when leaving the hot water heater. the incoming cold water instantly cooled the thermostat due to the proximity of the latter to the cold water supply. Thus, the boiler could work beyond the allotted time, and this significantly affected the financial costs.
Capillary. A more advanced type of thermostat, also working according to the laws of physics. The tube containing the temperature-sensitive liquid bottle is usually made of a material that does not oxidize for a long time. Inside the balloon is a liquid that has a different density from water. When heated, the density of the liquid changes, the volume changes accordingly, and the liquid presses on a special membrane, which turns off the power. Such thermostats are more accurate when compared with rod ones. The deviation in temperature is approximately 3°C.
Electronic. More modern type and, accordingly, more accurate. It usually works in tandem with a protective relay - if the boiler is empty when voltage is applied to the heating element, then the protection will work, which will turn off the power.

According to another classification, all thermostats can be divided into:

Electromechanical and electronic. The first type works due to bimetallic elements, the second - thanks to special electronic sensors.
Simple and programmable. In the first type, the temperature is set manually mechanically. The second type is more precise in its work.
Overhead and mortise. For boilers, the invoice type is most often used, if the control is electronic, and mortise, if the control is mechanical.

After carefully studying the articles on self-production, you can try to make a thermostat on your own.

Malfunctions and their solutions

How does a consumer notice a broken thermostat? As a rule, this is the most common way - the water is not heated in the boiler. In this case, either the heating element may be faulty, or the thermostat itself may be faulty, or (more rarely) both may be faulty. To check the latter, its resistance should be measured.

How to choose

But we should not forget: any independent actions without certain knowledge and strict adherence to safety rules can lead to a very unpleasant outcome.

The purpose of the thermostat for the water heater

The thermostat for a water heater is one of the elements of any boiler. If it were not for its presence in the design of the water heater, then calling such a device automatic would be a great exaggeration.