Buying a water heater is not an easy task, and you need to approach it responsibly, because you are purchasing a device on which the comfort of your family will depend for several years to come. Despite the fact that the boiler is for home use– the device is not complicated and, moreover, widespread; choosing it often becomes a real problem.
To purchase a suitable device, you need to know a lot about the types of water heaters and the main components of these devices. In this article we will tell you about such an important part of the boiler design as the thermostat.
Purpose
A thermostat is a device designed to keep the water temperature within specified values. It acts as a kind of “fuse”, protecting the device from overheating. The thermostat controls the temperature of the water in the tank, starting and stopping the heating process in time.
In addition to automating the operation of the device, the thermostat is responsible for the safety of using the water heater. After all, when the temperature rises above normal, the pressure inside the tank increases, and an uncontrolled increase in pressure can lead to an explosion of the device.
Principle of operation
Despite the fact that almost every manufacturer equips boilers with thermostats of different types, the operating principle of all devices of this kind will be the same.
To start desired value temperature is set by the user using a special regulator on the control panel of the water heater. Next, the water is heated to a set temperature, while a relay installed on the thermostat opens the contacts of the heating element.
When the water in the tank cools down, that is, the temperature drops below normal, the relay closes the contacts again, as a result of which the water heating process starts.
Kinds
Thermostats that water heaters are equipped with come in several varieties - rod, capillary and electronic. Let's look at each of them in more detail.
Rod
Rod thermostats are perhaps the oldest of all such devices. They are a small tube approximately 35 cm long and 1 cm wide. Under the influence high temperature the tube increases in size and presses on the switch. The disadvantage of such a system is its low accuracy, since the tube can quickly cool down, causing the boiler to work longer than necessary.
Capillary
Capillary thermostats appeared later than rod thermostats, but they have also been used for quite a long time. They are also made in the form of a tube, but inside there are cylinders with a liquid whose density is different than that of ordinary water. When heating occurs, the liquid increases in volume and the cylinder comes into contact with the membrane, which turns off the device. The accuracy of this type of thermostat is +/- 3 degrees.
Electronic
Electronic thermostats are the most modern and accurate of all of the above. For more advanced operation, they interact with a protection relay, which allows emergency power shutdown if the water heater tank is empty.
There is another classification of thermostats, according to which these devices are divided into the following types:
- electromechanical/electronic- depending on the key element management;
- simple/programmable– depending on the method of setting the temperature;
- overhead/mortise– depending on the installation method.
How to check if it's working properly?
Even the highest quality and most reliable boilers sometimes fail, and it often happens that the cause of malfunctions in the operation of the device is a breakdown of the thermostat. You can diagnose such a malfunction at home, without resorting to the help of a repairman.
- To find out whether the thermostat is working, you need to remove it from the water heater and switch it to resistance measurement mode.
- Then we set the maximum temperature value and measure the resistance at the input and output contacts of the device. If the device does not respond at all, most likely the thermostat is faulty.
- If a response occurs, move the regulator knob to the minimum value and reconnect the tester probes to the contacts.
- Next, take a lighter and use it to heat the thermostat tube.
After some time, the relay should operate, opening the circuit, and the resistance value will rush up. If this does not happen, then the thermostat is broken and needs to be replaced.
Connection and adjustment
If, after diagnosing the water heater, you find that the thermostat is faulty, you should replace this device with a new one. It is quite possible to do this on your own.
- Disconnect the water heater from the power supply.
- We block the water supply to the boiler and drain the remaining liquid from the tank.
- We remove the bottom panel of the device, opening access to the heating element.
- Remove the pressure ring of the heating element.
- We take out the thermostat sensors and the control unit.
- We install the new thermostat in place.
- We return the heater pressure ring to its place and secure the bottom panel.
- When going to the store to buy a new device, take the technical data sheet of the water heater with you. Knowing the necessary parameters, the seller will be able to select suitable model thermostat.
- Don't rush to throw away your broken thermostat before you get a new one. The marking on an outdated device is useful information, knowing which you can easily choose a new, identical thermostat, simply by showing it to the seller, or by entering it into the search bar of an online catalog.
If you choose a thermostat yourself, be guided by the following characteristics: type of device, dimensions, installation method, labor current, functionality (temperature control and/or protection).
Frequent malfunctions and repairs
Like any other device, the thermostat is subject to a variety of breakdowns, which can occur due to both external and internal factors. Let's list the most frequent malfunctions that happen with thermostats installed in boilers:
- wear of the copper capillary tube;
- poor interaction between the contacts of the thermostat and the heater;
- failure to adjust the heating element;
- scale formation;
- breakdowns caused by voltage surges.
Regardless of the type and cause of the malfunction, experts do not recommend do-it-yourself repair thermostat. It would be best to replace a broken device - this is the safest and most reliable solution to the problem.
If it is not possible to replace the thermostat with a new one, you can try to do it yourself. The following video will help you do it right.
Water heater thermostat - automatic regulator heating the boiler, controlling the heating limit and minimum temperature, at which the water should heat up again. Formally, this is a conditional fuse that switches off when the water has reached the maximum permissible heating temperature, and switches on when it has cooled down. If there is no such fuse, the water heater is a sealed container with a boiler that will heat the water until it explodes or fails.
The presence of a thermostat allows you not only to always keep the boiler ready for use, but also reduces electricity costs.
Principle of operation
The energy intensity and safety of any storage boiler depend on the thermostat, which automates the process of its operation.
The basis of its operation is to open the contacts of the heating element when the water reaches a given temperature, and when the latter cools, the tubular electric heater is turned on. The relay also operates when there is no water.
The main task of a thermostat is to control heating/cooling. On the one hand, it prevents water from boiling for too long, increasing the internal pressure in the tank in proportion to time. On the other hand, it keeps the boiler in constant readiness, so there is no need to wait for the water to heat up and you can start bathing procedures.
Advanced thermostats can provide additional signals. For example, if a heating element or other element breaks down, the device is forced to be disconnected from the power supply. The same thing happens if the heating element does not cope with its functions due to scale. In the latest models, the error code is indicated on the display, making it easy to determine the cause of the breakdown.
Kinds
Currently, there are several types of thermostats, among which there are 3 main ones:
- Rod
The most popular and most outdated of all those on the market today. This is a pipe minimum diameter, which works according to the laws of physics - when heated, it expands linearly and presses on the switch; when cooled, it contracts accordingly, and the heating element turns on.
The disadvantage of this design is the inaccuracy of operation associated with the location close to the water supply.
The storage boiler is designed in such a way that when hot water comes out, cold water immediately begins to flow into the tank so that the water level is the same all the time. Considering that the rod thermostat was located near the inlet cold water, it didn’t even have time to expand to the required size. The cold water instantly cooled it down, and the boiler worked almost non-stop during its use.
- Capillary
A more modern and therefore thoughtful way of thermoregulation. It is based on the same small-diameter tube in which the capsule with contrast liquid was located. When water was heated to a certain temperature, the structure of the liquid and its volume changed, as a result of which the relay tripped. When the water cooled below a predetermined level, everything happened the other way around - the liquid decreased in volume, and the relay was activated to turn on. The permissible deviation in water temperature is +- 3-4 degrees.
- Electronic
The most convenient and accurate type of thermostat that responds to a specific water temperature. Moreover, there is a protective relay that opens the power supply circuit if there is no water in the tank.
By technical specifications Thermostats are divided into:
- electronic and mechanical - in the first version, bimetallic elements are triggered, in the other - an electronic temperature control sensor
- programmable and mechanical - in the first option a specific temperature is set, in the second it triggers either boiling or the maximum level is set manually;
- overhead and built-in - with electronic control, the first option is used, with mechanical control - the second.
It is noteworthy that thermostats are designed not only for individual storage water heaters, but also for indirect heating. This is not entirely convenient, although it is very economical. Water in in this case is heated by a specific heating element without interfering with its main functions. Of the minuses - the coolant also heats up to a certain point, respectively, hot water at indirect heating there will never be. If you like to take a cool shower and want to save money, this will be the best option.
Malfunctions and how to fix them
Unfortunately, any design tends to break, and the thermostat is no exception. As a rule, such devices are not repaired, preferring to buy a new one, similar or with increased resistance. But if you use it correctly and follow it basic rules, its service life will be much longer than the warranty.
The main problem is that the water stops heating. In this case, there are 2 options - out of order a heating element(you will learn how to clean the heating element and replace the magnesium anode in the article). The second option is a broken thermostat. To check this, measure its resistance. If there are no changes on the test device, it's time to go to the store for a new thermostat.
How to choose the right thermostat
There is no point in repairing the thermostat; moreover, this requires specialized knowledge. It is much easier, faster and cheaper to buy a new one and install it.
- when purchasing a new one, be sure to show the seller the technical data sheet for the water heater - they will select the model that suits it exactly;
- You shouldn't throw away the relay first and then buy it. Each unit has a special marking that will allow you to choose, if not identical, then exactly suitable for a specific model;
- at independent choice of the device, take into account the dimensions, current and resistance, and functional characteristics.
How to make a replacement
Ideally, if the manufacturer has offered more profitable terms cooperation, for example, increased guarantee period, and then the replacement process should be entrusted to professionals.
According to the well-known law of breakdown household appliances and electronics in 99.99% of cases occur at the moment when the warranty has expired.
If your warranty period and time have expired free service, you can do the following:
- Completely disconnect the water heater by unplugging the plug from the socket.
- Close the pipe with cold water(a supply tap is provided for this).
- Drain all the water by first opening the hot tap, then unscrew it from the bottom, unscrew it and remove it protective cover and let the rest drain off.
- Unscrew the nuts, remove the flange and the pressure ring of the heating element. We remind you to use a bowl to collect water, it will continue to flow.
- Pull out the thermostat sensor and disconnect the control relay.
- Install the new thermostat on the boiler, return the pressure ring and screw the casing on with a Phillips screwdriver. It is advisable to photograph the entire process to avoid mistakes.
- Turn on the water supply and monitor the boiler for 2-3 hours for the tightness of the lid and the tank as a whole, then operate it as usual.
How to replace a thermostat - on video
The thermostat for a water heater works on the principle of a thermometer - it measures the temperature. Why this is necessary and what the risk of element failure is, read in our publication.
The design and principle of operation of the thermostat
How does the device work? On the control panel you set the heating parameters. As soon as the water reaches the specified parameters, the temperature sensor is triggered, sending a signal to the control module. The latter gives the command to turn off the heating element.
IN storage boilers The water is always warm thanks to the temperature regulator. As soon as the indicators decrease, the heating element starts up again and continues heating. Therefore, you can get hot water at any time, without long waits.
IN modern models The thermal relay is equipped with a shutdown button - thermal protection. When the heating element overheats or heats the contents above the specified norm, the protection is triggered and the operation 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 the water heats up. The extension triggers the heater switch off key.
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 react in time to the temperature increase.
- Capillary. The design is the same, but in this case the tube contains liquid, which expands and activates the heating element relay. The error is 3-4 degrees.
- Electronic. The most accurate of all sensors. Equipped with protection against turning on without water.
The following regulators have been developed for electric water heaters:
- Mechanical and electronic (overhead and built-in, respectively). Mechanical ones are triggered by the expansion of bimetallic plates, electronic ones by a sensor signal.
- Programmable and mechanical. The first require setting the required indicators, the second are triggered when boiling or when the maximum manually set temperature is reached.
Has the boiler stopped heating or, on the contrary, is it overheating 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.
- Turn off the water supply.
- Drain the contents of the tank. You can use a special valve for this. , read in a separate article.
- Dismantle the heating element. To do this, unscrew the nuts and bolts of the flange and 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, you can clean bimetallic plates from oxidation. To do this, soak a piece of cloth in alcohol and wipe the plates. If the oxidation has spread greatly, then clean it with fine sandpaper.
You need to do this carefully so as not to touch the sensor contacts.
Due to power surges, the break contact could become stuck. To adjust, carefully remove it from the body, clean problem area. Normally, the contact should fit into the socket automatically.
How to repair a contact if it does not 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 insulating tape underneath.
- Reinstall the stem.
- Assemble the body.
When the regulator needs replacement
There is no point in carrying out repairs if:
- The copper tube has become unusable.
- The electronics have failed.
- The element burned out due to a power surge.
But how can you be sure in practice that the thermostat 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. If the resistance is infinite, the thermostat cannot be restored and must be replaced.
- Does it show resistance? Do this: set the multimeter to the minimum value. Use a lighter to warm up the thermostat tube. If it is working properly, the resistance will increase and the protective relay will operate.
If you are convinced of a malfunction, it is important to choose a suitable product for replacement. How to do it? It is best to take the old regulator and go with it to the store to purchase an analogue. Or write down the serial number that is on each product.
What to pay attention to:
- Fastening method.
- Size.
- Voltage.
- Additional functions.
The parameters must match those specified in the passport for the boiler.
If you are not good at repairs, then you can call a specialist to replace it.
Remember safety precautions and watch the video
The water heater allows you to create comfortable conditions residence due to constant provision of hot water.
The main components of any water heater are:
You can find out the price and buy heating equipment and related products from us. Write, call and come to one of the stores in your city. Delivery throughout the Russian Federation and CIS countries.
- outer casing, which can be metal, plastic or a combination;
- an internal tank, which is usually made of stainless steel;
- thermostat / thermostat, which will be discussed below;
Thermostat for water heater
A safety thermostat for a water heater is a device for keeping the water temperature within the specified 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, promptly starting and stopping the heating process.
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 increase. And if you do not monitor the pressure, the system may explode.
Principle of operation
Each manufacturer equips water heaters different types thermostat, but the principle of operation of the device still remains the same.
The thermostat opens the contacts of the heating element if the water reaches the desired temperature value, and when the liquid cools, the heating element 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 provide additional signals. For example, if a tubular electric heater breaks down, then next step the system will be automatically disconnected from the power supply. Or, for example, a shutdown will occur according to the same pattern if the heating element fails to cope with its duties due to plaque.
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 look. It is a small diameter tube 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 operation, since its location is close to the water supply.
The storage boiler is designed so that when leaving hot water, cold water immediately enters the tank so that the water level is always the same. Since the rod thermostat is located near the cold water supply, it has critically little time left to expand to required sizes. The cold liquid quickly cools it, and the boiler functions almost non-stop during its use.
Rod thermostat for water heater
Capillary protective The thermostat for the water heater is more modern solution. It consists of the same small-diameter tube containing a capsule with contrast liquid. Such a thermostat changes its volume depending on 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 it is also considered modern version. For better functioning, it interacts with a protective relay. This makes it possible to switch off the power in an emergency if the water heater tank is empty.
Ariston electronic water heater thermostat
Of course, there are other classifications of thermostats. If we consider from the side of the main control element, we can distinguish electromechanical and electronic devices. If we take the method of indicating temperature as a basis, then there are simple and programmable ones. Surface-mounted and mortise thermostats are distinguished based on the type of installation.
How to check the thermostat
Failure of the thermostat - common reason breakdowns of even the highest quality boilers. You can notice problems yourself, without outside specialized help.
The most frequent problems, associated with thermostats, may be the following:
- the copper capillary tube is worn out;
- failure in the settings of the heating element;
- the appearance of plaque;
- malfunctions due to voltage surges;
- poor coordination of contacts between the heater and thermostat.
To check your water heater thermostat you will need a multimeter.
How to check the thermostat of a water heater or how to “ring” the thermostat on a water heater:
- First, find out if the thermostat is working. To do this, remove it and switch it to resistance measurement mode.
- The next step is to set the maximum temperature value and measure the resistance at the output and input contacts of the device. The thermostat design is most likely faulty if the device “does not respond” at all.
- If, nevertheless, the design is working properly and has responded, then you need to move the regulator knob to the lowest setting and reconnect the tester probes to the contacts.
- Finally, use a lighter to heat the thermostat tube. If the system is working properly, then the relay should respond, opening the circuit, and the resistance indicator will jump.
How to choose the right one
It is safe to say that if the thermostat breaks down, it will be simpler, easier and cheaper to buy a new one.
You can select a thermostat for a water heater of a specific model, taking into account the geometric dimensions of the tubular electric heater, its power, and also based on the volume of the tank of the water heating structure.
But you need to consider the following points:
- When you go shopping, take with you the technical passport of the water heating structure to show the seller. The seller will help you choose the right model for this particular case and not make a mistake.
- Do not throw away the relay. It can be useful when choosing an identical device (after all, each has its own marking).
- If you choose a device yourself, then consider the dimensions, current and resistance, as well as performance characteristics.
The thermostat not only keeps the water heater in working condition, but also makes electricity consumption more economical. This is one of the main components water heating structure, so you should pay special attention to it.
We offer Italian temperature controllers Thermowatt, Reco, MTS Group, etc., which have long proven themselves in spare parts household appliances. They have reliable characteristics, long service life and a minimum percentage of defects. A thermostat (thermostat) is needed to maintain desired temperature water by turning the heating element on or off in automatic mode. Protection (bipolar thermal protection or bipolar safety) of the thermostat is triggered when a critical temperature is reached, when the standard shutdown at the upper limit does not work. Such sensors save approximately 20% of thermal energy. Our catalog includes rod, capillary, bimetallic, and electronic thermostats. Rod thermostats are installed in threaded and clamping heating elements, on the flange of which there are connectors with contacts and are distinguished by the shape of the control head, the temperature adjustment range, and the length of the rod.
Types, classification
The main function of a boiler thermostat is to maintain the desired temperature. The second function is protective. They are divided according to the type of execution into: rod, capillary and in the form of a “tablet”. Rods are divided by length into short 220 mm, medium 270 mm and long 450 mm. According to their purpose, thermostats are divided into:
- adjustable - maintaining the temperature in the desired range in automatic mode. When the maximum temperature in the thermostat is reached, a relay is activated, which turns off the heating of the heating element and automatically turns it on when the temperature drops when the lower limit of the temperature range is reached;
- protective - set the temperature value at which the heating element turns off. After such a shutdown, the water heater can only be turned on manually. Usually the temperature is set to close to 100°C, avoiding boiling of the water in the water heater;
- adjustable-protective - include both types.
- rod;
- capillary;
- bimetallic;
- electronic.
Reasons for failure
The temperature measurement sensor in rod and capillary thermostats is a sealed system in the form of a sealed tube with liquid, which expands or contracts when heated or cooled. It gives a signal to close or open the network. In bimetallic thermostats, the role of liquid is played by different metal plates, which also change their position due to temperature changes, closing or opening the circuit. If for some reason this functionality is broken, then disabling will not work. There may be several reasons:
- water entering the thermostat due to a leaking heating element;
- expiration of service life;
- voltage fluctuations, malfunctions.
Replacing the thermostat in a water heater
The thermostat is replaced entirely, since its repair is unprofitable in financially. Inexpensive rod and capillary ones, electronic ones cost several times more. Replacing this device is an easy task as it does not require draining the water. It is enough to disconnect the contacts and wires, remove the old thermostat and connect the new one in the same way. Usually such a replacement takes no more than half an hour. To purchase, add the item to your cart and place your order. If you have questions about selecting or purchasing a thermostat, call or write to online help. Our managers will select the one you need, help you place your order, or place it over the phone. We are waiting for your questions and orders.
