The water in the boiler is heated as follows: water enters the heat exchanger, the heating elements heat the liquid to the set temperature. When it cools, the heating element is turned off. The thermostat for a boiler is a device that supports the set temperature mode.
Features and types of thermostats
The thermostat has 3 functions:
- turns off the heating of water when the temperature of the liquid 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 switches off the device in order to prevent its breakdown.
The principle of operation is simple: the device closes the contacts when the water is cooling and opens when sufficiently heated. The thermostat is equipped with an alarm indicator. When the device is working, the indicator is on; when it is turned off, it goes off.
There are 3 main types of regulators.
Rod
The easiest and most affordable option. This is a tube made of material capable of linear expansion. With increasing temperature, 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 closer or further to the connection point.
The disadvantage of the core model is inaccuracy. The device is installed near the cold water supply system, therefore it cools to a greater extent than the heated liquid. As a result, the water is heated to a higher temperature than indicated.
Capillary
It consists of a tube made of anti-corrosion materials and a capsule inside, filled with a contrast fluid. When the water heats up, it expands and presses on the membrane. The membrane opens the contacts. When cooling, the liquid decreases in volume and closes the contacts.
A capillary thermostat is more accurate, since liquids cool and heat simultaneously and equally.
Electronic
The electronic temperature sensor for the boiler is the most accurate. Water is heated to the indicated temperature. Thanks to its own protection, the device lasts longer. Distinguish between the adjustment and the protective version. The latter is connected to a protective relay. The device turns off the device if there is no water in the tank.
Bimetallic
The measurement indicator here is not liquid in the capsule, but plates of two different metals. When heated and cooled, the metal plates expand in different ways and change their location. At the same time, they close or open the contacts of the heating elements. Plus devices - great reliability and simplicity. This type of thermostat can be repaired, as its main breakdown is a loose circuit.
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- Electronic
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- Bimetallic
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- Capillary
How to choose a thermostat
Upon purchase, the boiler is equipped with a regulating device. But when it fails, the owner has to purchase a new one.
The temperature controller for the boiler is selected taking into account the following parameters:
- The model should correspond to the size of the water heater, the size of the tubular electric heater and its power. For reliability, it is better to bring a product data sheet with you to find out all the parameters on the spot.
- Do not throw out the relay with a worn out 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.
An electronic thermostat provides water heating and reduces current consumption.
Replacement and connection
Damage to the thermostat is a common problem. The diagnostics are not complicated; the owner of the boiler can carry it out. How to ring the thermostat on the water heater is described in the instructions.
- The device is removed from the boiler and transferred to the resistance measurement mode.
- Indicate the maximum permissible temperature and measure the resistance at the contacts. If the thermostat does not respond, it has become unusable. You can’t fix it, you need to change it.
- If the thermostat responds, set the minimum temperature and measure the resistance again with the tester. Then, with the help of a lighter, the device body is heated.
- If the thermostat is working properly, it must 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 changed.
It is much easier to install a thermostat for any boiler than a pump or a heat exchanger. It is best to buy the same model, but if the brand of the device is rare or this model is out of date, you can find another option that matches the parameters.
- Disconnect the device from the mains, shut off the water supply and drain the water.
- Remove the lower part of the boiler, thereby gaining access to the heating elements. The pressure ring of the heating element is removed.
- The temperature sensors and the control module are removed. Remove the thermostat and install a new one in its place.
- The clamping ring is returned and fixed and the bottom panel is replaced.
- They 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.
By marking a broken thermostat, it’s easier to find a new one. Do not immediately discard 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 notify the owner of the nature of the failure.
Symptoms:
- 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 temperature of the liquid reaches the specified value; the device overheats, you can only turn it off manually by disconnecting it from the power supply;
- on mechanical boilers, an indicator does not light, indicating the functionality of the thermostat.
How to check the operation of the thermostat on the water heater is indicated in the instructions. The causes of the problems are as follows:
- wear of the copper tube in the thermostat - it is easier to buy a new device than to restore the old one;
- loose closure of the three-pin temperature controller and the heater - the position of the contacts can be adjusted;
- failure of the control unit - the item 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.
Replacement can be done by yourself. However, if the boiler is under warranty, you need to contact a service workshop.
Range of thermostats for boiler
Temperature regulators differ in size, shape, device. However, among the manufacturers of these devices, the best can be distinguished. These are high-quality, durable and reliable products:
- Devi - a company from Denmark, operates in the market of heating elements since 1942. Initially, the company produced appliances for industrial needs. But already in the 60s the assortment was expanded. Now it 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. It specializes in various types of household electrical appliances. A feature of the products is adaptation to unstable operation of the power supply network, power surges, poor quality water. The company’s temperature regulators are very popular in the Russian market due to their resistance to adverse operating conditions.
- Techem is a Swedish company. The main proposal is automated heat, gas, water metering devices and devices for regulating parameters. The products are of high quality, but are expensive.
- Valtec is an international organization that produces engineering plumbing and household electrical appliances. Products adapted to Russian conditions. This is a very common brand in Russia.
A water heater cannot work without a thermostat; this is an obligatory element of the device. Mechanical models are often equipped with a simple rod device. More modern boilers are equipped with electronic devices that can accurately control the temperature of the liquid.
