Servo for heating - the basis of "smart" heating system
In the past, there were no particularly stringent requirements for heating systems - it was enough that the room was warm. In addition to reliability, a modern heating system must also ensure the possibility of temperature control over a wide range. The servo drive is designed to make the heating as responsive as possible, it allows you to adjust the temperature in the room to the degree

Scope of application
In the heating system, it can be installed in different places, for example, if it is necessary to regulate the flow of coolant into the heater, it is installed on the supply pipe. But the servo valve of the heater valve will allow to regulate the flow of air into the boiler furnace, that is, the heater power will be adjusted (see also the article Modern Heating Terem - high quality at an affordable price).

Adjusting the temperature in the room is often done in two ways:
- with the help of thermostats - The best option in case of heating radiators. In this case, the regulators are installed in front of each battery and automatically regulate the flow of coolant into the radiator;
- using servo - most often used when necessary to adjust the temperature of underfloor heating.
Note! Servos can be installed on the heating manifold comb instead of the usual thermal heads.

In the case of warm floors, it is especially important to keep the coolant no higher than a certain temperature. If, for example, to regulate the flow of coolant using conventional temperature controllers, then when starting the system, a situation may arise when hot water flows into the pipes. As a result, it will simply be uncomfortable to walk on the floor for a while, and a failure of a part of the pipes is possible.
Installing a servo with a 3-way valve to the manifold will avoid this. I usually do this, especially since the price of such a device is minimal.
Read more about the design
Servomotors can be divided into 2 groups of devices - electromechanical and electrothermal. In the first, mechanical engagement is used to set some part in motion. In electrothermal devices, instead, the property of a liquid (gas, solid) is used to change the volume when heated, and they are used in heating systems.
When choosing a particular model, you need to know the notation used, there may be such options as:
- normally open / closed;
- voltage 230 or 24 V.
With voltage everything is clear - 230 V means powering the device from the network, and 24 V - from batteries. But the open / closed directly related to the mode of operation and the scope of the device.
- normally closed type when closing the circuit, water flows through the pipe section, this is the type used in heating;
- normally open - on the contrary, when the circuit closes, it blocks the movement of the substance through the pipe, such devices are used mainly in air conditioners, refrigeration equipment.
Device and principle of operation
The main element of this device can be called a sealed chamber with a corrugated wall. Inside this chamber there can be gas, liquid, or a solid - when heated it will change the dimensions of the bellows (hermetic chamber) and regulate the current of the substance through the pipe.
During operation, a thermostat located anywhere in the room signals the servo that the temperature exceeds the optimum. The circuit closes and current begins to flow through it.
When this occurs, the bellows is heated and lengthened. When lengthening the bellows begins to press on the valve stem, reducing the passage hole in the pipe.

The design is spring loaded, so that after the circuit is opened again and the bellows cools down, the spring will return the pusher to its original position, and the bore hole will increase in size.
Installation Features
When self-installing the servo instruction will look like this:
- First, a thermostat is installed in the room - it will record the change in air temperature;
- then a two- or three-way valve is installed (the characteristics of each type of valve are discussed below);
- A servo actuator is installed directly on the valve and is connected to the thermostat. The device is powered.
Note! In 4-core servo drives, 1 contact is provided for the possible connection of other devices.
If all the connection work is done correctly, then the LED on the servo head should light up, according to its color, you can judge the position:
- the blue color indicates that the device is currently de-energized, that is, it is in the open state;
- a green light indicates that the device is energized, that is, the servo is closed.

Using two and three way valves
The actuator can be used with two, three and four way valves. In heating systems, the first 2 types of valves are most often used.
Two-way servo valves are usually installed in front of the radiators. Such a device has only an inlet and an outlet, and a change in the orifice allows to regulate the passage of coolant through the valve. Installation of the regulating device is done by hand.

Three-way ones offer much more features. Installing the servo drive allows not only to regulate the coolant current through it, but also, if necessary, to isolate the heating circuits from each other.

Note! Separation of heating circuits is simply necessary when using conventional radiator and low-temperature heating (floor heating).

When thermoregulated, the actuator on a 3-way valve can, for example, arrange for mixing in the water supply pipe from the return pipe. This gives a 100% guarantee that a too hot heat transfer fluid will not get into the heater.
Summarizing
The use of servo drives allows for high flexibility in adjusting the heating system. At the same time, the cost of such a device is low, and the ease of installation only adds to its popularity. Such a heating system will make it possible to adequately and quickly respond to the slightest change in temperature in the house (see also the article Installing Heating: Tips on Selecting Components of an Autonomous System).
The video shows an example of the installation of a servo on the heating collector.