How to check the boiler temperature sensor. Electronic thermostat for boiler

The water heater allows you to create comfortable conditions residence due to the constant provision of hot water.

Check price and buy heating equipment and related products you can with us. Write, call and come to one of the stores in your city. Delivery across all territory of the Russian Federation and the CIS countries.

The main components of any water heater are:

• outer case, which can be metal, plastic or a combination;
• internal tank, which is usually made of stainless steel;
• thermostat / thermostat, which will be discussed below;

Thermostat for water heater

The safety thermostat for a water heater is a device for keeping the water temperature within the set values. It is called "protective" because its main function is to protect the device from overheating. It regulates the temperature of the water in the tank, timely starting and stopping the process of its heating.

In addition to automating work, the thermostat is responsible for the safety of using water heating equipment. Because if the temperature rises, the pressure in the tank will also rise. And if you do not monitor the pressure, then an explosion of the system can occur.

Principle of operation

Each manufacturer equips water heaters different type thermostat, however, the principle of operation of the device still remains the same.

The thermostat opens the contacts of the heater if the water reaches the desired temperature value, and when the liquid cools, the heater turns back on. This is the principle of operation of the water heater thermostat.

Its task is to control the heating and cooling of water.

A modern water heater thermostat can give additional signals. For example, if a tubular electric heater breaks down, the next step is to automatically disconnect the system from the power supply. Or, for example, according to the same pattern, a shutdown will occur if the heating element fails to cope with its duties due to a raid.

Types of thermostats

Water heaters can be equipped with different thermostats. The main types are rod, capillary, electronic.

Rod thermostat for a water heater - this is today the most popular type. It is a small tube in diameter that functions according to the laws of physics. When heated, the tube expands linearly and presses on the switch, and when cooled, it contracts and turns on the heating element.

It has the disadvantage of inaccurate work, since its location is close to the water supply.

The storage boiler is designed so that when hot water leaves, cold water immediately enters the tank so that the water level is always the same. Since the rod thermostat is located near the supply cold water, then it has critically little time to expand to the right sizes. cold liquid quickly cools it, and the boiler operates almost non-stop during its use.

Rod thermostat for water heater

Capillary protective water heater thermostat is more modern solution. It consists of the same tube of small diameter, in which there is a capsule with a contrast liquid. Such a thermostat changes its volume from the temperature in the heater tank. With a certain heating, water presses on the membrane, which is connected to electrical contacts.

Capillary thermostat for water heater

Electronic thermostat for a water heater is also considered modern version. For better functioning, it interacts with a protective relay. This makes it possible emergency shutdown supply when the water heater tank is empty.

Electronic water heater thermostat Ariston

Of course, there are other classifications of thermostats. When viewed from the side of the main control element, it is possible to distinguish electromechanical and electronic devices. If we take as a basis the method of indicating the temperature, then there are simple and programmable. Overhead and mortise thermostats are distinguished based on the type of installation.

How to check the thermostat

Failure of the thermostat - common cause breakdowns of even the highest quality boilers. You can notice problems yourself, without outside specialized help.

by the most frequent problems associated with thermostats can be the following:

• the capillary tube made of copper has worn out;
• failure in the settings of the heating element;
• the appearance of a raid;
• malfunctions due to voltage drops;
• poor matching of heater and thermostat contacts.

You will need a multimeter to test the water heater thermostat.

How to check the water heater thermostat or how to "ring" the thermostat on the water heater:

1. First, find out if the thermostat is working. To do this, remove it and switch to resistance measurement mode.
2. In the next step, set the maximum temperature value and measure the resistance at the output and input contacts of the device. The design of the thermostat is most likely not working if the device does not “respond” in any way.
3. If, nevertheless, the design is working and responded, then you need to turn the regulator knob to the smallest indicator and reconnect the tester probes to the contacts.
4. At the end, use a lighter to heat the thermostat tube. If the system is working, then the relay should respond, which opens the circuit, and the resistance indicator will jump.

How to choose

It is safe to say that if the thermostat breaks down, it will be easier, easier and cheaper to buy a new one.

Choosing a water heater thermostat specific model it is possible, taking into account the geometric dimensions of the tubular electric heater, its power, and also relying on the volume of the tank of the water heating structure.

But you need to take into account the following points:

1. When you go shopping, take the technical data sheet of the water heating structure with you to show the seller. The seller will help you choose the right model in this particular case and not be mistaken.
2. Do not throw away the relay. It can be useful when choosing an identical device (after all, each has its own marking).
3. If you choose a device yourself, then consider the size, current strength and resistance, as well as performance.

The thermostat not only keeps the water heater in working condition, but also makes electricity consumption more economical. This is one of the main constituent parts water heating design, so you should pay special attention to it.

The thermostat for the water heater plays the same important role, like 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.

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 is lowered (forced or naturally) and the thermostat again gives a signal to the heating element to begin its direct duties.

Separate, specially designed, types of thermostats have additional function- 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:

1. 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.
2. 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.
3. Electronic. More modern type and therefore 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:

1. Electromechanical and electronic. The first type works due to bimetallic elements, the second - thanks to special electronic sensors.
2. Simple and programmable. In the first type, the temperature is set manually mechanically. The second type is more precise in its work.
3. 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- thermostats that 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 circulating in heating system the liquid 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.

By carefully reading the articles self-manufacturing, 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, at correct operation thermostat breakage 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, there may be either a malfunction heating element, or a malfunction of the thermostat itself, or (more rarely) a malfunction of both elements. 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 desired device and install it. 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.

The purpose of the thermostat for the water heater

In domestic boilers, the temperature sensor is an unpretentious capillary-type thermostat. In most cases, its service life is quite high. Mine broke after three years of work. You won't find it in the city. Tell me how to make the simplest thermostat for a water heater with your own hands?

Our expert answers the question:

The temperature sensor in household boilers can be replaced with an electronic temperature controller. The diagram is easy to find. The most commonly used circuit is a thermostat on a zener diode tl 431.

The main components of the thermostat

There are several varieties of it. Small changes in original scheme allow for smooth temperature control:

• a variable resistor (33 kOhm) is shifted towards a higher temperature in order to obtain smooth adjustment;
• stabilizer functions 7805 can take on the same domestic production KR142EN5A;
• the switch is changed to the KM1-1 button;
• you can make 12V stabilization by replacing the zener diode and transistor with KR142EN8B.
• you can connect a color indicator that will signal the standby mode for subsequent activation;
• mounted on the body led indicator power supply of the KL102 board.

The temperature sensor itself is mounted at the bottom storage water heater through a sealed tube. Its length depends on the capacity of the water heater and is half the length of the tank. The capillary sensor of the thermostat is placed in this tube.

Sequencing

A failed sensor can be replaced as follows:

• prepare a PUNL 2x1.5 wire 50–60 centimeters long;
• remove the insulation from the wire along a length of 40 centimeters and wrap one core with FUM tape;
• take a thermistor and solder wires to the cores;
• wrap FUMka the entire structure along the entire length;
• one edge is treated with zapon-lacquer, clamps are installed on the second.

The resulting device is placed in the tube and fixed with a simple electrical tape. This is done to quickly remove the thermostat if necessary.

Prepared electronic circuit connected to the temperature sensor with a shielded wire, which helps to reduce interference. Close the contacts that connected the previous sensor, otherwise the circuit will remain open.

The design is ready to go, however, it does not look very nice. The principle of "minimum intervention" allows you to return everything to its original position.

Video: Repair of a thermostat on a water heater

The thermostat for a water heater works on the principle of a thermometer - it measures the temperature. Why this is necessary and what threatens the breakdown of the element, read in our publication.

How does the device work? On the control panel you set the heating values. As soon as the water reaches the set parameters, the temperature sensor is triggered, sending a signal to the control module. The latter gives the command to turn off the heating element.

AT storage boilers the water is constantly warm thanks to the temperature controller. As soon as the indicators decrease, the heating element starts up again and continues heating. So you can get hot water at any time, without long waiting.

AT modern models the thermostat is equipped with a shutdown button - thermal protection. When the heating element overheats or heats the contents above the specified norm, the protection is activated and the work stops. Otherwise, the heating element will burn out.

Device Diagram:

There are several types of thermostat:

• Rod - obsolete type, no longer used. It is based on a tube that expands when water is heated. From the extension, the heater switch-off key is triggered.
  This design was abandoned due to its inaccuracy. The part was located close to the cold flow intake, so it did not have time to respond to an increase in temperature in time.

• Capillary. The design is the same, but in this case the tube contains a liquid that expands and actuates the heating element relay. The error is 3-4 degrees.

• Electronic. The most accurate of all sensors. Equipped with protection against switching on without water.

For the electric water heater, regulators have been developed:

• Mechanical and electronic (overhead and built-in, respectively). Mechanical ones are triggered by the expansion of bimetallic plates, electronic ones are triggered by a sensor signal.
• Programmable and mechanical. First you need to install required indicators, the latter are triggered by boiling or when the maximum manually set temperature is reached.

The boiler stopped heating or, on the contrary, overheats the water? The thermostat is checked first.

How to do DIY repairs

If possible, the element can be repaired or a new one installed.

How to remove the thermostat:

• Disconnect the equipment from the network.
• Shut off the water supply.
• Drain the contents of the tank. To do this, you can use a special valve. , read in a separate article.
• Dismantle the heating element. To do this, unscrew the nuts and bolts of the flange, remove it from the housing.
• The thermostat is usually located at or near the base of the heater.

• Disconnect the wiring and remove the sensor from the base.

In the case of a mechanical model, clean bimetallic plates from oxidation. To do this, soak a piece of cloth in alcohol, wipe the plates. If the oxidation has spread greatly, then clean with fine sandpaper.

This must be done carefully so as not to touch the sensor contacts.

Due to power surges, the NC contact could stick. To adjust, carefully detach it from the body, clean trouble spot. Normally, the contact should be in the socket automatically.

How to repair a contact if it doesn't work:

• Remove the part completely from the housing.
• Clean its surface, as well as the seat.
• If the contact does not turn on after cleaning, place an insulating tape underneath.
• Reinstall the stem.
• Assemble the body.

When the regulator needs to be replaced

It makes no sense to repair if:

• The copper tube has fallen into disrepair.
• The electronics are out of order.
• The element burned out during a power surge.

But how in practice to make sure that the thermal relay is faulty? This can be checked with a multimeter.

• Set the multimeter to resistance measurement mode, as shown in the picture:

• Attach the probes to the contacts of the part.
• Look at the scoreboard. With infinite resistance, the thermostat cannot be restored, a replacement is needed.
• Show resistance? Do this: set the multimeter to minimum value. Heat the thermostat tube with a lighter. If it is working, the resistance will increase and the protective relay will work.

If you are convinced of a malfunction, it is important to choose the right product for replacement. How to do it? It is best to take the old regulator and go to the store with it to purchase an analogue. Or write down the serial number that is on each product.

What to look for:

• fastening method.
• The size.
• Voltage.
• Additional functions.

The parameters must match those indicated in the passport for the boiler.

If you are not strong in repair, then you can call the master for a replacement.

Remember safety and watch the video

2016-12-14 Evgeny Fomenko

How to fix a thermostat

The first stage of repair is to disconnect the water heater from the electrical network, then drain the water, remove the heating element from the water heater. Remove the thermostat from the heating element by carefully pulling it out. Drill out the copper rivets holding the body, disconnect the body from the stem, this must be done carefully so as not to damage anything.

There are two methods for cleaning bimetallic plates: if the contamination (oxidation) is not very strong, try cleaning it with a cloth soaked in alcohol, inserting a piece between the plates and wiping it, but if such cleaning does not work, clean the plates with sandpaper of the finest grit. It is even better if it is already used, so as not to break contacts.

It is possible that the breaking contact (rocker) has stuck to the housing. To fix this problem, disconnect the contacts, clean this place. The opening contact should return to the top position automatically.

If this does not happen, remove the "rocker" from the device, clean it with a finely abrasive sandpaper, clean the place where it is installed (there may have been sticking of melted plastic), install it in its original place. If the "rocker" still does not return to its original place, glue a piece of insulating tape under it, choosing such a thickness that the contact plate returns to its upper position.

Insert the rod back, screw the body with self-tapping screws, insert it back into the heating element.

In addition to the above, there are the following possible faults thermostat, which are eliminated only by replacing it:

• The copper tube has worn out.
• Electronics failure.
• Malfunction resulting from voltage fluctuations.

If you find that your device has stopped working, there are ways to check the malfunction yourself. To check the operation of the thermostat for the water heater, you will need to remove the thermostat and set it in resistance change mode. We set the maximum possible temperature, we measure the resistance in the input and output contacts of the device.

In the case when the device shows infinite resistance, we can safely conclude that it is malfunctioning. And if there is resistance, then turn the regulator to the most small value and reconnect the tester to the contacts. Further, with the help of a lighter or a candle, we heat the tube of the device, if the device is working, the relay will work, which closes the circuit, the resistance indicator will increase. If this does not happen, the device is defective.

If it was not possible to repair the thermostat, in order to select a suitable device, the following recommendations should be followed. by the most right decision will be the acquisition of the same device, the same manufacturer.

However, if you did not find it, when choosing, pay attention to its dimensions, the method of attachment to the water heater, the number of functions performed (only temperature control, or also protective), the voltage for which it is designed. When buying a new one, do not forget to take a technical passport for the boiler, or a failed device.

Video about the thermostat device: