Modern energy sources have a fairly high cost, so every owner of an apartment or a country house is thinking about how to make the heating system more energy efficient. Not so long ago, users did not have the opportunity to regulate the supply of heat to the room, thereby saving consumption. The construction industry is constantly improving, and special devices are now available — thermostatic valves. These are simple, reliable and inexpensive elements that allow you to maintain the desired air temperature in the room and regulate energy consumption. The principle of operation, types and features of the thermostatic valve will be discussed below.

thermostatic valve

Purpose of the device

It happens that in the premises, in addition to radiators, other heat sources act — household appliances, gas or electric stoves, and so on. On sunny days, the temperature rises and the house becomes warmer than usual.

Important! The task of the thermostatic valve installed on the radiator is automatic temperature control, during which it takes into account temperature fluctuations in the room at a height of up to 2 meters.

The thermostatic valve for radiators ensures the reliability of thermal equipment. By including it in the heating system, a comfortable and optimal room temperature is achieved and, at the same time, money spent on energy consumption is saved. The valve stabilizes the operation of the heating system if the pressure drops or disappears in it.



There is a wide variety of models of such valves, but their design is similar.

Mandatory layout includes the following elements:

  • body, usually made of brass;
  • a mixer used as a directional regulator;
  • control lever;
  • other small parts in the form of seals, nuts and so on.

The valve body has 2 inlets and 1 outlet. A liquid of different temperatures enters through the inlets, and through the outlet it exits, already heated to the required temperature. In the inner part of the housing there is a mixer that regulates the direction. This element, depending on the valve model, functions differently. A simple option — a spring locking element is installed in the design, which reacts to temperature, and, accordingly, pressure. If the spring tension increases, the outlet temperature decreases.

The control knob is needed in order to set a specific position of the valve. With its help, the spring stiffness is set and the position of the locking part is adjusted.

Valve design

Principle of operation


In the body of the device, in the front and right pipes, the coolant circulates until its temperature reaches the set value. The thermostatic valve is installed in order to maintain a given outlet temperature by mixing cold or hot water into the liquid. If the parameters do not converge, then the external drive of the device acts on the rod. When it starts to move, all 3 channels open in the body. And, as soon as the temperature parameters stabilize, the front inlet pipe is closed.

There is a considerable variety of thermostatic valves and three-way valves. One of the varieties is similar to a ball valve. In this model, the changeover valve consists of a recessed ball rather than a cone seat. To redistribute the coolant, the drive acts on the rod with the fixed ball, rotating it. Such valves have a low throughput, therefore they are used only in domestic heating systems. In short, a thermostatic valve sets the required water temperature.

What are the types of valves

Design features are not the only thing that distinguishes modern thermostatic valves. These elements are made of various materials, have different diameters and connection methods. Let’s get acquainted with the main types.

Production material

The main condition is that the material from which the valve is made must be resistant to mechanical stress and corrosion. This is explained by the fact that the element is in constant contact with the liquid — the coolant.

The material from which the valve is made determines the performance and technical characteristics of the product. It is recommended that the valve be made of copper, brass or cast iron. Copper options are expensive, but last a long time. Brass samples also have a long service life and do not cause difficulties during operation. In general, in order to make the right choice, it is better to seek advice from the company’s specialists who will set up the heating system.


Control method


According to this parameter, devices of 2 types are distinguished:

  • electrical;
  • manual.

Often a manual version is installed, visually similar to an ordinary ball valve. More modern models with electric filling are popular in private homes — they are controlled automatically, distributing heat throughout the room. Adjusting the thermostatic valve is simple — the user sets the desired heating temperature for each room and the device supplies the working fluid to the heater. If desired, such a system is combined with a «warm floor», but it is necessary to think over a way to create a protective coating for pipes.

Wiring diagram

Having figured out what the valve consists of and on what principle it functions, we will consider various schemes for connecting it. It all depends on the purpose for which the thermostatic balancing valve is installed.

What is a valve for?

  1. Protects the solid fuel boiler from the effects of condensate and temperature shock, which happens as a result of a sudden power outage.
  2. So that the coolant circulating in the «warm floor» system does not warm up above +45 degrees Celsius.
  3. Maintains the required temperature of the coolant in the heating system, and hence the pressure in the pipeline.

To protect the thermal unit operating on solid fuel, it is not allowed that cooled water from the heating system enters its circuit. To do this, the boiler is connected according to a special scheme, which includes not only a mixing valve, but also a bypass. The operation of the circuit is as follows: the coolant will circulate in a small circle through the bypass until the heat generator warms up. When the temperature reaches +50-55 degrees Celsius, the valve will start to open, mixing cold water from the system. When the boiler reaches operating temperature, the bypass is closed and all flow begins to flow through the radiators.

Similar functions and when connected to the «warm floor» system. The pump circulates the coolant in the circuit until it cools down. As soon as this happens, the sensor and valve are activated and hot water from the boiler will be added to the system.

This important detail is also used when tying a solid fuel boiler and a buffer tank, which plays the role of a heat accumulator. For its effective heating, the temperature of the coolant should reach + 70-85 degrees Celsius, which is higher than the norm for radiators. The thermostatic valve is used to lower the temperature. To do this, it is installed behind the tank, paired with pumping equipment.

Note! When installing a mixing valve, the pump should be located on the side where the always open branch pipe of the tap is located.


Often, thermostatic changeover valves are installed in large cottages with a complex heating system, with a hydraulic arrow and a distribution manifold. Each circuit in such a situation requires a certain temperature. The highest heat value is needed by the boiler, therefore, the regulating temperature is not supplied to it. But for the rest of the consumers, a not so hot coolant is supplied, so they are connected through thermostatic valves.

Valve type

Installation Features


Heating systems are assembled according to various schemes, which will determine the location of hot water pipes, plugs and control valves. Before starting the installation, you need to shut off the coolant supply to the radiator and drain the remaining water.

With a single-pipe heating system, hot water circulates through one pipe, and heating devices are connected in series. The coolant is supplied to the radiator through a special pipe installed on top. In the circuit, it passes through the battery and exits on the other side, redirecting to the highway. With this connection, the thermostat is mounted on a bypass connecting the direct and return pipes of the heating device. And even if the valve is closed, hot water will still continue to move. Thermostat failure can occur if bypasses are not installed under the pipes. If one battery is disconnected, then not only the valve will fail, but the entire heating system will fail.

In two-pipe systems, things are different, since in it the coolant is supplied through one pipe, and it is discharged through the other. A jumper, that is, a bypass, is not required in this situation, so a thermostatic valve is installed on the supply pipe. The control valve is also effective in individual heating systems. It is also relevant for centralized networks, but taking into account the fact that a hot water meter is provided.

Valve installed in the heating system

Before you start setting the thermostat, you first need to isolate the room from heat loss. To do this, close all doors and windows. Next, the valve is set to maximum heat output and the heating is turned on, after which the temperature in the room is measured. After its increase by 5 degrees, the valve is closed. Now you need to wait a bit and slowly open the regulator until the water comes out. This position should be remembered.


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