The heating of water in the boiler is as follows: water enters the heat exchanger, heating elements heat the liquid to the set temperature. When it cools down, the heating element turns off. A thermostat for a boiler is a device that maintains a set temperature regime.
Features and types of thermostats
The thermostat has 3 functions:
- turns off water heating when the liquid temperature reaches the desired level;
- when the water temperature drops below the specified value, the thermostat turns on the heating elements;
- when the boiler overheats, the thermostat turns off the device to prevent its breakdown.
The principle of operation is simple: the device closes the contacts when the water is cooled and opens when there is sufficient heating. The thermostat is equipped with a signal indicator. When the device is working, the indicator is on, when it turns off, it goes out.
There are 3 main types of regulators.
Rod
The easiest and most affordable option. This is a tube made of a material that can expand linearly. As the temperature rises, it increases in size, presses on the contacts and opens them. When the water cools, the rod shortens and closes the contacts. Depending on the set temperature, the thermostat is located closer or farther to the connection.
The disadvantage of the core model is inaccuracy. The device is installed near the cold water supply system, therefore it cools more than the heated liquid. As a result, the water heats up to a higher temperature than indicated.
Capillary
Consists of a tube made of anti-corrosion materials and a capsule inside filled with contrast liquid. As the water heats up, it expands and presses against the membrane. The diaphragm opens the contacts. When cooled, the liquid decreases in volume and closes the contacts.
A capillary thermostat is more accurate because liquids are cooled and heated at the same time and in the same way.
Electronic
The electronic temperature sensor for the boiler is the most accurate. The water is heated to the specified temperature. Thanks to its own protection, the device works longer. Distinguish between adjusting and protective options. The latter is connected to a protective relay. The device turns off the device if there is no water in the tank.
Bimetallic
The indicator of measurement here is not the liquid in the capsule, but plates of two different metals. When heated and cooled, the metal plates expand in different ways and change their position. At the same time, they close or open the contacts of the heating elements. The advantage of the device is its great reliability and simplicity. This type of thermostat can be repaired, since its main breakdown is a loose circuit.
How to choose a thermostat
The boiler is equipped with a regulating device upon purchase. But if it fails, the owner has to buy a new one.
The thermostat for the boiler is chosen taking into account the following parameters:
- The model must correspond to the dimensions of the water heater, the dimensions of the tubular electric heater and its capacity. For reliability, it is better to take the technical data sheet of the product with you in order to find out all the parameters on the spot.
- Do not throw it away with a worn out relay device. It will also help in choosing the right thermostat.
- It is necessary to take into account the dimensions of the device itself, the permissible current strength, resistance and other characteristics.
The electronic thermostat warms up the water and reduces the current consumption.
Replacement and connection
A breakdown of a thermostat is a common problem. Diagnostics is not difficult, it is within the power of the owner of the boiler to perform it. How to ring the thermostat on the water heater is described in the instructions.
- The device is removed from the boiler and put into resistance measurement mode.
- Indicate the maximum allowable temperature and measure the resistance at the contacts. If the thermostat does not respond, it has become unusable. You cannot fix it, you need to change it.
- If the thermostat responds, set the minimum temperature and measure the resistance again with the tester. Then, using a lighter, the body of the device is heated.
- If the thermostat is working properly, it should open the contacts when heated. In this case, the resistance at the input and output should increase. If the water continues to heat up, the device must be replaced.
The thermostat for any boiler is much easier to install than a pump or heat exchanger. It is best to buy the same model, but if the brand of the device is rare or this model is outdated, you can find another option that matches the parameters.
- Disconnect the device from the mains, shut off the water supply and drain the water.
- The lower part of the boiler is removed, thereby gaining access to the heating elements. Remove the heating element clamping ring.
- They remove the temperature sensors and the control module. Remove the thermostat and install a new one in its place.
- Return and fix the pressure ring and replace the bottom panel.
- Check the operation of the device by filling the boiler with water and setting the minimum temperature values. If, after heating to the specified value, the device turns off, everything is in order.
It is easier to find a new one by marking the broken thermostat. Do not immediately throw away the boiler parts.
Self-help troubleshooting
A water heater is a fairly simple device. Some malfunctions in it can be eliminated, diagnostics can also be performed by yourself. If an electronic or programmable control unit is installed, the latter will also notify the owner about the nature of the breakdown.
Malfunction symptoms:
- the water does not heat up - the thermostat, the temperature sensor, and the heating element may be to blame;
- the display shows heating data that does not correspond to the truth;
- the boiler heats the water, but does not turn off when the liquid temperature reaches the specified value; the device is overheating, you can turn it off only manually by disconnecting it from the mains;
- on mechanical boilers, the indicator does not light up, indicating the functionality of the thermostat.
How to check the operation of the thermostat on the water heater is indicated in the instructions. The reasons for the problems are as follows:
- wear of the copper tube in the thermostat - it is easier to buy a new device than to restore an old one;
- loose closure of a three-contact thermostat and heating element - the position of the contacts can be adjusted;
- failure of the control unit - the element must be replaced;
- the appearance of scale on the heating elements, due to which the contact between the heater and the thermostat is broken - it is enough to clean the heating elements;
- the device has failed due to a power surge - it cannot be repaired.
You can replace it yourself. However, if the boiler is under warranty, you need to contact a service workshop.
Boiler thermostat assortment
Thermostats differ in size, shape, device from each other. However, among the manufacturers of these devices, the best ones can be distinguished. These are high-quality, durable and reliable products:
- Devi - a company from Denmark, has been operating on the heating element market since 1942. At first, the company produced devices for industrial needs. But already in the 60s, the range was expanded. It now supplies both domestic and industrial heaters and thermostats.
- Mondail Electronics Co is a Chinese manufacturer offering household and electrical appliances and products for the light industry. The range also includes thermostats for different types of boilers. According to reviews, the products are quite reliable and resistant to stress.
- RTCElectronics is a South Korean company. Specializes in various types of household electrical appliances. A feature of the product is adaptation to unstable operation of the power grid, power surges, low-quality water. The company's thermostats are very popular in the Russian market due to their resistance to adverse operating conditions.
- Techem is a Swedish company. The main offer is devices for automated metering of heat, gas, water and devices for regulating parameters. The products are of high quality, but they are expensive.
- Valtec is an international organization that manufactures plumbing engineering and electrical appliances for household use. The products are adapted to Russian conditions. This is a very common brand in Russia.
A water heater cannot work without a thermostat, this is a mandatory element of the device. Mechanical models are often equipped with a simple rod fixture. More modern boilers are equipped with electronic devices that can accurately regulate the temperature of the liquid.
