What is the purpose of a thermostat in a water heater and how does it work? Thermostat for a water heater: operation of the device, troubleshooting, tips for efficient operation. Thermostat in a water heater, operating principle.
The thermostat for a water heater is often called a thermostat. Remember this so as not to get confused in concepts and not fall into a stupor when you discuss the issue of choosing a boiler and thermostat for a water heater.
- 1 Features and types
- 2 Operating principle
- 3 Fault detection
- 4 Selecting a thermostat
Features and types
In fact, the thermostat performs a fairly simple function from a theoretical point of view, but a complex one from a practical point of view. Namely, it maintains optimal temperature indicators, turning on and off the operation of another component of the water heater - the heating element.
In the event that problems arise with the heating element, the heating element fails, the thermostat performs another function - protective. It’s called thermal protection, that is, emergency shutdown of the boiler.
Now regarding the types of thermostats. There are three in total.
- Rod. It is inserted into a tube, which is located on the body and has a length of about 25-50 centimeters;
- Capillary. They are also made in the form of a tube, inside of which there is liquid. It changes its volume depending on the temperature at one time or another inside the tank. When the desired or specified temperature regime, the liquid acts on the membrane, which, in turn, is connected to the contacts;
- Electronic. The boilers include special thermal resistances that react when the temperature of the water inside the device changes. As a rule, it has two electronic regulators at once. The first is responsible for temperature, and the second is for protection. Of course, such devices are the most expensive, but also the most effective.
When choosing a water heater with one or another thermostat, take into account the fact that you may need to replace components if they fail. This process doesn't have to be very expensive. Whatever one may say, thermostats can be called consumables, exactly like heating elements, that is, heating elements.
Principle of operation
If we take into account the main aspects of the operation of thermostats, then we can briefly talk about it as follows.
- The required temperature is set on the boiler. For this purpose, there may be provided on the body various designs- switches, buttons, levers;
- When the mode is set, the thermostat will measure what temperature the water is in this moment, then turns on the heating element if necessary;
- As soon as the temperature reaches a given level, the circuit breaks, as a result of which the heating element stops working, that is, heating the water in the container;
- When the water cools, and this necessarily happens, the thermostat detects the drop in temperature, closes the circuit again, after which heating continues.
Fault detection
Let us note right away that such an element as a thermostat for a water heater cannot be repaired, that is, if it fails, it should be immediately replaced with a new component. But first you need to determine that the old device is faulty.
If you notice that the heating element does not work when the voltage is turned on, it is quite possible that the regulator is broken. To check its performance, you should remove it from the tank and measure the resistance, which is calculated in Ohms using a special device. Set the adjustment knob to maximum and check the resistance at the contacts. If the tester remains stationary, then the component has failed. Buying a new thermostat is not at all difficult, but there are some nuances.
Selecting a thermostat
The best option would be to purchase the same element that has failed. By contacting the store where you purchased the heater, there is a good chance you will find the required component. However, sometimes it is difficult to find an identical temperature controller, and therefore you will need to find an analogue. To do this, pay attention to:
- Type of regulator, its dimensions, as well as methods of fastening in the boiler;
- Functions performed, that is, adjustment, protection, or two functions at once;
- The current that your old thermostat was designed to handle.
It is obvious that thermostats are playing important role in the correct functioning of the water heater. It’s not difficult to replace it even yourself, and it’s not difficult to find the necessary thermostat on the market. The main thing is to know the characteristics of the failed element in order to select a new one by analogy. But this is in case it was not possible to purchase the same thermostat, which does not happen very often.
Buying a boiler for heating water is not as simple as it might seem at first glance. You can’t just go to the store and buy the first model you come across. In fact, this process requires maximum care so that the equipment lasts for a long time and does not cause trouble. In general, the design of a water heater is not complicated, and it is quite possible to carry out the connection and even repair it yourself. However, when choosing, you should pay attention to what kind of thermostat is installed in it, for example, with or without temperature control.
There are some classifications of thermostats, according to which a water heater can be divided into several types. Electromechanical-electronic, which affects the control method. Programmable or simple, which will affect how the temperature is set. Mortise or overhead, which affects the installation method.
Basically, a thermal switch is:
- Rod;
- Capillary;
- Electronic.
The peculiarity of the rod model is that it is the oldest device. It looks like a small tube, 35 cm long and 1 cm wide. When it is affected heat, the tube expands in size and pressure is applied to the switch. This is exactly how this system works.
It has its own drawback, and it lies in low accuracy, because the tube cools as quickly as possible, due to which the water heater operates longer than required.
The operating principle of the capillary thermostat is slightly improved, since it appeared after the rod thermostat. The thermostat is a tube with cylinders located inside it. They contain liquid with a density different from water. When heated, the volume of liquid increases, the cylinder begins to put pressure on the membrane and on the shutdown device. By accuracy this method has a discrepancy of 3 ᵒС.
Thermal sensor electronic form- This is the most common model and it is the most accurate compared to the others. The perfection of the model lies in the fact that the temperature sensor has direct interaction with the protection relay, due to which emergency automatic shutdown power if there is no liquid in the tank.
Purpose of a thermostat for a water heater
In addition to all of the above, the thermostat is responsible for safe work boiler. To be more precise, as the water temperature rises, the pressure inside the sealed tank also increases, and if given growth will be uncontrollable, then an explosion will soon occur. This can be dangerous not only for equipment, but also for human health if you are nearby at that moment. A temperature regulator is a device through which the optimal temperature level is also maintained.
This is a kind of thermal valve that prevents:
- Overheat;
- Explosion;
- I damage not only equipment, but also nearby property.
It is he who is responsible for controlling the heating of water at the moment when the device is connected, as well as for ensuring that the heating element is blocked in time. Almost every manufacturer strives to equip the boiler with a thermostat. Products come different models However, the principle of operation is the same for all of them. At the moment when you need to connect the equipment to the network, you need to immediately adjust the water heating level.
This can be done through the control panel located on the device body.
Next, controlled water heating is carried out, and a relay installed on the thermostat is responsible for opening the contacts of the heating element. When the tank cools completely, the temperature drops below normal, and the contacts of the heating element of the relay close, due to which the system starts up, and the liquid in the tank heats up again.
How to connect and adjust a thermostat for a water heater
If the boiler does not work, then you do not need to start it again, waiting for a phenomenal turn on, but check the product for damage. If it is determined that the problem is with the thermostat, then replacement is required. Repairs do not cover the sensor and, as a rule, you simply purchase a new part. How to replace the thermostat?
You don’t need a wizard, just don’t violate the instructions below:
- The water heater is disconnected from the network.
- The valve supplying water to the tank is closed, and all the liquid in it is drained.
- The bottom panel of the device is removed, which allows you to get close to the heating element.
- Next, remove the pressure ring in the heating element.
- The sensor in the thermostat and the control unit are removed.
- A new thermostat is being installed.
- Be sure to install the pressure ring in place and secure the bottom panel.
A couple of simple movements will save you maximum money, time and effort. In order to choose a protective thermostat for a water heater, you should follow certain recommendations from experts. When you go to purchase a new thermostat, you should take with you the technical data sheet for the boiler. This will make it much easier for the seller to navigate which model and with which operational features fits better Total. It is strictly forbidden to throw away a broken product before purchasing a new one.
The marking, which is applied by the manufacturer and is a kind of identification mark, may be useful.
You need to choose a thermostat that is exactly the same model, since there is minimal difference in size or characteristic features can lead to breakdown of the entire boiler. When choosing a thermostat yourself, you need to focus on the type of product, parameters, installation method, and what it has labor force current and functionality.
Frequent malfunctions of the thermostat for heating elements
Any device in the house can break down, even if we are talking about a high-quality and super expensive boiler. The cause of the breakdown can be absolutely any factor, both external and internal.
There are a number of main breakdowns that you should definitely pay attention to:
- The copper capillary tube is worn out.
- The three-pin thermostat and the heater do not interact well with each other.
- There was a failure in regulation heating element.
- Scale has formed.
- A breakdown occurred due to voltage fluctuations.
It is worth noting that if you do not have any skills and knowledge regarding working with a thermostat, then it is best to have this part replaced and repaired in the boiler by a specialist, so that there is no uncertainty about the correctness of the actions performed, and the device regularly performs its direct duties.
Checking the thermostat for the boiler for serviceability
Some time after installation, the operating diagram of any heater, at least indirect heating, even a normal one, may fail. How to check a product's suitability?
It is quite possible to carry out diagnostics without the intervention of a specialist:
- To determine the suitability of the thermostat, it must be removed from the boiler and set to the mode in which the resistance is measured.
- The maximum temperature level is set and the resistance at the input and output contacts of the product is measured. If the device does not respond, then the thermostat is faulty.
- If there was a response, then the knob on the regulator is turned to the minimum level and the resistance is checked again.
- Next, you need to take a lighter and heat the tube in the thermostat with it.
After a few minutes, the relay should automatically operate, opening the circuit. In this case, the resistance value should be directed upward. If this is not the case, then the thermostat is broken and needs to be replaced.
Troubleshooting, replacing the thermostat (video)
In conclusion, we note that during any work, you need to protect yourself by wearing dielectric gloves, glasses and avoiding contact with the supply voltage. In order to choose a thermostat, thermostat and type of heating element, you first need to familiarize yourself with their features and disadvantages, as described above.
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 term service and minimum defect rate. A thermostat (thermostat) is needed to maintain the desired water temperature by turning the heating element on or off automatically. Protection (bipolar thermal protection or bipolar safety) of the thermostat is triggered when it reaches critical temperature, 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, 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. Upon reaching maximum temperature a relay is activated in the thermostat, 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
Temperature sensor in rods and capillary thermostats- This is a sealed system in the form of a sealed tube with a liquid that, when heated or cooled, expands or contracts. 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.
The thermostat for a water heater plays as important a role as the 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 set value.
This is what the device looks like for adjusting the temperature of water heating and for emergency shutdown
Then the heating element stops working. The water temperature drops (forcibly or naturally) and the thermostat again signals the heating element to begin its direct duties.
Separate, specially designed types of thermostats have additional function– turn off the power supply to heating element in case of breakdown of the latter. This avoids the possibility of electrical shock, which often happens with ungrounded boilers.
Types of thermostats
Today, many types of thermostats have been developed, but if we talk about devices specifically for boilers, the three most successful are:
- 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 operating principle is based on the elementary laws of physics: when heated, the tube expands linearly, which allows you to press the switch. Such thermostats for a long time were the most common in boilers. However, their accuracy left much to be desired - when leaving the water heater hot water. the incoming cold water instantly cooled the thermostat due to the latter’s close location to the inlet cold water. Thus, the boiler could work beyond the allotted time, and this significantly affected financial costs.
- Capillary. A more progressive type of thermostat, also working according to the laws of physics. The tube in which the temperature-sensitive cylinder with liquid is located is usually made of a material that cannot be oxidized over a long period of time. Inside the cylinder there 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 thermostats. The temperature deviation 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 supplied to the heating element, then the protection will work and 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 electronic special 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 overhead type is most often used if the control is electronic, and the mortise type if the control is mechanical.
Another interesting option– thermostats designed for indirect heating boilers. Such boilers allow you to heat water using only power for heating device, which means there are significant savings. But circulating in heating system the liquid cannot heat above a given level, while for a boiler the consumer may need a different temperature (and most often this happens). In this case, you should buy a thermostat specially designed for this purpose.
Having carefully studied the articles on self-production, you can try to make a thermostat yourself.
Malfunctions and their solutions
The thermostat for your water heater may fail. Unfortunately, such phenomena are not uncommon, but there is nothing fatal here. 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, when correct operation water heater thermostat breakdown can be avoided or, in extreme cases, its life can be significantly extended.
How does a consumer notice a broken thermostat? As a rule, this is the most common method - the water is not heated in the boiler. In this case, there may be either a malfunction of the heating element, or a malfunction of the thermostat itself, or (less commonly) a malfunction of both elements. To check the latter, its resistance should be measured.
If during testing the picture on the display of the test device does not change, you need to buy a new thermostat. It's not that much money, so there's no need to grieve. Another option for testing the thermostat is possible: measuring the resistance when the thermostat itself heats up. If even then the test device does not show any changes, that’s it, now it’s time to go to the store.
How to choose
Typically, a faulty thermostat can be replaced with a similar one in shape and operating principle. However, if it is possible to buy and install another thermostat and there is an urgent need for it, then why not. The main thing is to be able to choose the right device and install it correctly. Although here, too, the consumer can be helped by the Internet or a consultant at the point of sale.
But we should not forget: any independent actions Without certain knowledge and strict adherence to safety regulations, they can lead to a very unpleasant outcome.
It would seem that the heating element or volume should be important in a 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 heating device.
Purpose of a thermostat for a 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.
IN domestic boilers The temperature sensor is an unpretentious capillary-type thermostat. In most cases, its service life is quite long. After three years of operation, mine broke down. You can't find it in the city. Tell me how to make a simple 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 temperature regulator based on a tl 431 zener diode.
Main components of a thermostat
There are several variants of its varieties. Small changes to original diagram allow for smooth temperature control:
- variable resistor (33 kOhm) is shifted to the side higher temperature to obtain smooth adjustment;
- The functions of the 7805 stabilizer can be taken over by the same domestic production KR142EN5A;
- the switch is replaced with a 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;
- An LED power indicator for the KL102 board is mounted on the case.
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 installed in this tube.
Sequencing
A failed sensor can be replaced as follows:
- prepare a 2x1.5 PUNL 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 the entire structure along its entire length with foam tape;
- One edge is treated with tsapon-varnish, and clamps are installed on the second.
The resulting device is placed in the tube and secured with simple electrical tape. This is done to quickly remove the thermostat if necessary.
Prepared electronic circuit connects to the temperature sensor with a shielded wire, which helps reduce interference. The contacts that connected the previous sensor are closed, otherwise the circuit will remain open.
The design is ready for use, although it doesn’t look very nice. The principle of “minimal intervention” allows you to return everything to its original position.