How servos and three-way valves work

In this article, I will discuss how to understand the operation of three-way valves and servos (electric actuators).

What is a valve?

Valve- this is a mechanism that serves to allow or not to allow liquid or gas to pass from one space to another. Moreover, the valve can be open or closed by a certain percentage. That is, valves can serve to regulate the passage of liquids or gas. The movement of liquid or gas is carried out due to the pressure difference between the sides of the valve.

There are two most common types of valves in a heating system:

Saddle (saddle) type– has a sleeve and a direct volumetric body that blocks the passage.

Ball (or rotary) type- has a body that, due to its rotation, leads to the opening or closing of the passage.

Ball valves have the highest flow capacity compared to the seat type valve. That is, ball valves achieve lower hydraulic resistance.

Valves are:

Two way valves– have two connections on opposite sides of the valve. For example, they are used to pass liquid or gas on one circuit. That is, they close or open one branch of the water supply or heating system.

Three way valves– They have three connections. They are used primarily for mixing or separating liquid or gas flows. The main operation of a three-way valve is necessary either to obtain a certain temperature or to redirect flows. In heating systems, temperature control is needed to regulate the indoor climate. Flow redirection usually serves to redirect the heated coolant from the heating system to the boiler indirect heating. There are also many other tasks...

Four way valves– They have four connections. Performs the same job as three-way valves. But there may be other tasks.

Communication between servos and valves

In a heating system, there are several ways of interconnecting valves and valve control elements (servo drive and thermomechanics):

1. Thermostatic mixer- usually called a mechanism that contains both a valve and a device that changes the position of the valve automatically. Varies depending on the temperature of the liquid or gas. This device has a mechanism that, under the influence of temperature, changes the elastic force and because of this, the valve moves. Depending on the servo drive, such a valve does not require electricity. The temperature is adjusted by rotating the handle. Typically, some valves are designed for a small temperature range. Maximum up to 60 degrees. There may be exceptions from other manufacturers.

2. Ways to use individual elements without resorting to servos. For example, a thermostatic valve with a thermal head. There are thermal heads that have a remote sensor.

3. Valves and servos are separate elements. The servo is attached to the valve and controls the valve.

What is a servo drive?

Servo- This is a device that carries out the operation of the valve movement. The valve, in turn, either allows or does not allow liquid or gas to pass through. Or it passes it in a certain amount depending on pressure, valve position and hydraulic resistance.

What types of servos are there?

There are also thermal drives, which are also called servos.

But in this article we will only analyze electric drives (servo drives)

Electric drives come in two directions:

A complete package (set) is when the device already has a full set of functions. For example, the kit already includes a temperature controller and an electric temperature sensor. It is possible to immediately adjust it to the desired temperature. Setting the test time for valve movement. Connects directly to an alternating current network of 220 Volts with a frequency of 50 Hertz. Standard for Russia. It is possible to adjust it in different directions of movement of the ball type valve. It is possible to configure it to rotate 90 or 180 degrees. You can set any value, even 49 degrees or 125 degrees. And this is done inside a black box. See the instructions for details.

I told you one of the options. Of course, there are a dozen other options... Also, servos vary in the speed at which the valves close and open. This example serves to smoothly adjust the valve to mix the flows different temperatures to get the reference temperature.

This option serves to redirect coolant flows.

This option is used to redirect the coolant flow from the boiler either in the direction of radiator heating or to heat an indirect heating boiler. The specified servo needs a 220 Volt signal. Moreover, there are three contacts. One is general, and the other two are for redirecting traffic. The easiest option when you need to redirect flows in the heating system on demand from the thermostat of an indirect heating boiler.

Servo actuators are classified according to the type of movement: saddle valve type or ball (rotary) valve type.

If you are selecting a servo drive for a valve, be sure to specify the type of movement of the servo drive. Also, the seat type of servo drive does not always match all types of seat valves. With rotary ball valves there seems to be a universal standard, but with seat valves everything is not so simple. There is no one standard.

Electric drive as a separate link in automation.

Let's consider an analog servo drive from Valtec art. VT.M106.R.024

Such a servo drive requires a constant 24 Volt power supply and a control signal from 0 to 10 Volts.

That is, if the voltage is 0 Volts, then the rotating mechanism is in the 0 degree position. If 5 Volts then 45 degrees. If 10 Volts then 90 Degrees.

Such a servo drive is supplied with a signal from a special controller, which has a function for supplying a 0-10 Volt signal. Depending on the temperature and the temperature controller setting, the controller supplies a different voltage from 0 to 10 Volts. There is a rotation setting: Hourly and counterclockwise. Of course, in order to find more detailed information about the signals and connection diagram, ask the manufacturer for a passport with detailed diagram signal management.

I repeat... That mentioned in this article, not all signals are described. There are many other signals...

What is a controller?

Controller– This device is designed to control signals for various logical tasks. The controller is the brain of the automatic system. It determines, depending on the program, which signals need to be sent at one time or another.

There are a variety of controllers that perform different tasks.

The following tasks are usually performed for a heating system:

The most common task is to obtain the set temperature of the coolant.

Depending on the temperature, receive a signal (For example, turn off the boiler or pump). The controller may include a contact relay. That is, dry contact. These contact relays can be set to produce any voltage. For example, 220 Volts turn on or off a pump or send a signal to a servo drive to redirect flows.

You can also use the controller to turn off the boiler in cases critical temperatures. The signal from the controller is sent to power powerful contactors, which in turn power powerful electric boilers.

The cheapest controller of the TRM series

Sold by ARIES, they have a lot of interesting things you can pick up. owen.ru

The logic of the work is very extensive... In the future I plan to write and develop more useful material on automation systems for heating and water supply systems. Register your email to receive notifications about new articles.

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A series of video tutorials on a private home
Part 1. Where to drill a well?
Part 2. Construction of a water well
Part 3. Laying a pipeline from the well to the house
Part 4. Automatic water supply
Water supply
Water supply for a private home. Operating principle. Connection diagram
Self-priming surface pumps. Operating principle. Connection diagram
Self-priming pump calculation
Calculation of diameters from central water supply
Water supply pumping station
How to choose a pump for a well?
Setting up the pressure switch
Pressure switch electrical diagram
Operating principle of a hydraulic accumulator
Sewage slope per 1 meter SNIP
Heating schemes
Hydraulic calculation of a two-pipe heating system
Hydraulic calculation of a two-pipe associated heating system Tichelman loop
Hydraulic calculation of a single-pipe heating system
Hydraulic calculation of radial distribution of a heating system
Scheme with a heat pump and solid fuel boiler - operating logic
Three-way valve from valtec + thermal head with remote sensor
Why the heating radiator in an apartment building does not heat well
How to connect a boiler to a boiler? Connection options and diagrams
DHW recirculation. Operating principle and calculation
You are not calculating the hydraulic arrow and collectors correctly
Manual hydraulic heating calculation
Calculation of warm water floors and mixing units
Three-way valve with servo drive for domestic hot water
Calculations of hot water supply, BKN. We find the volume, power of the snake, warm-up time, etc.
Water supply and heating designer
Bernoulli's equation
Calculation of water supply for apartment buildings
Automation
How servos and three-way valves work
Three-way valve to redirect the flow of coolant
Heating
Calculation of thermal power of heating radiators
Radiator section
Overgrowth and deposits in pipes impair the performance of the water supply and heating system
New pumps work differently...
Calculation of infiltration due to pressure drop
Calculation of temperature in an unheated room
Heat regulators
Room thermostat - operating principle
Mixing unit
What is a mixing unit?
Types of mixing units for heating
Characteristics and parameters of systems
Local hydraulic resistance. What is KMS?
Bandwidth Kvs. What is it?
Boiling water under pressure - what will happen?
What is hysteresis in temperatures and pressures?
What is infiltration?

IN wide range Shut-off valves used for heating systems contain an element that is used quite rarely. Its shape resembles a tee, although the functions it performs are completely different. We are talking about a three-way valve, the operating principle of which will be discussed in this article.

Operating principle of three-way valve

What is this device and why is it needed?

How does this work

Three way valve mounted on those sections of highways where it is necessary to divide the flow of circulating fluid into 2 circuits:

• with variable hydraulic mode;
• with constant.

In most cases, a constant flow is required by those for whom the liquid is supplied high quality and in the indicated volumes. It is regulated in accordance with quality indicators. As for the variable flow, it is used for objects where quality indicators are not the main ones. There great value has a quantity coefficient. Simply put, the coolant is supplied there according to the required quantity.

Pay attention! TO shut-off valves This also includes an analogue of the device described in the article - a two-way valve. How is it different? The fact is that the three-way option works on a completely different principle. The rod included in its design is unable to block the flow of liquid, which has constant hydraulic parameters.

The rod is open all the time, it is adjusted to a particular volume of liquid. Consequently, users will be able to get the volume they need, both in terms of quantity and quality. In general, this device is unable to stop the flow of fluid to a network in which the hydraulic flow is constant. In this case, it may well block a flow of variable type, due to which, in fact, the possibility of adjusting the flow/pressure arises.

And if you connect a pair of two-way devices, you can get one, but three-way. But it is necessary that both work in reverse, in other words, when one valve closes, the next one must open.

Video - Three-way valve operating principle

Valves classification

Without lengthy introductions, we note that the device can be of two types according to the principle of operation. It could be:

• dividing;
• mixing.

The features of each type of action are clear from their names. The mixing device consists of two outputs and an input. In other words, it is necessary to mix fluid flows, which may be required in order to reduce its temperature. By the way, this is the most best option in order to set the desired mode in the “warm floor”.

The procedure for adjusting the temperature regime is extremely simple. You just need to know about the current temperature indicators of the incoming liquid flows, accurately calculate the required proportions of each of them so as to obtain the required indicators at the output. By the way, this device, subject to proper installation and adjustment, can also function as a flow separation device.

But the separating valve divides one flow in two, therefore, it is equipped with one inlet and two outlets. This device is used primarily to separate the flow of hot water in hot water systems. Although quite often it is found in the piping of air heaters.

Externally, both options are almost identical. But if you look at their cross-sectional drawing, their main difference is immediately visible. The rod, which is installed in a mixing-type device, has one ball valve. It is located in the center and blocks the main passage.

As for separating devices, the stem has two such valves, which are installed at the outlets. They function according to the following principle: one of them is pressed against the saddle, closing the passage, and the other, in parallel, opens passage No. 2.

By control method modern models may be:

• electrical;
• manual.

In most cases, a manual device is used, which in appearance resembles an ordinary ball valve, but is equipped with three outlet pipes. But electric models having automatic control, are used mainly in private homes, namely to distribute heat. For example, the user can set the temperature regime by room, and the working fluid will flow in accordance with the distance of the room from the heating device. As an option, you can combine it with a “warm floor”.

Video - Device in a boiler group

Three-way valves, as well as other devices, are determined in accordance with the pressure in the system and the diameter of the inlet. All this is regulated by GOST. And if the requirements of the latter are not met, this will be regarded as a gross violation, especially when it comes to the pressure indicator in the line.

Areas of application

The three-way valve, the operating principle of which was discussed above, has a fairly wide range of applications. Thus, its varieties, such as an electromagnetic device or a device with a thermal head, are often found in modern pipelines, where it is necessary to adjust the proportions when mixing two separated liquid streams, but without reducing power or volume.

As for household use, the most popular here is a thermostatic mixing device, with which, as noted above, you can regulate the temperature of the working fluid. This liquid can be supplied both to the “warm floor” pipeline and to heating radiators. And if the valve also has automatic control, then you can control the temperature in your home without any problems!

Pay attention! The use of a three-way valve in a heating system to balance temperature changes is extremely beneficial not only in terms of comfort and convenience, but also in terms of cost savings.

The fact is that by regulating the temperature of the liquid at the “return” of the heating device, you can significantly reduce the volume of fuel consumed, and this will have a positive effect on the efficiency of the system itself. In some systems, a valve is simply necessary. For example, in a “warm floor” system, this device prevents overheating flooring above a given level of comfort, thereby relieving users of unpleasant sensations.

Regulating devices of this kind are also used in water supply systems in order to obtain a permanent flow at the required temperature. The simplest example is an ordinary mixer, in which you can make water hotter/cooler by opening/closing a cold tap.

Adjusting the flow of working fluid. What to look for when purchasing?

Manual adjustment is carried out using the usual ball valve. Visually it is very similar to a simple valve, but has additional output. Fittings of this kind are used for forced manual control.

As for automatic adjustment, a special three-way valve is used here, equipped with an electromechanical device to change the position of the rod. It should be connected to a thermostat in order to be able to regulate the temperature in the room.

Remember that when purchasing a valve, it is imperative to take into account the technical parameters of the device, which include the following.

• Diameter of connection to the heating main. Often this indicator varies from 2 to 4 centimeters, although much depends on the characteristics of the system itself. If a device of a suitable diameter cannot be found, you will have to use special adapters.
• The possibility of installing a servo drive on a three-way valve, the operating principle is discussed at the beginning of the article. Thanks to this, the device will be able to work automatically. This point is very important if the device is selected for operation in “ warm floors» water type.
• Finally, there is the pipeline capacity. This concept refers to the volume of liquid that can pass through it in a certain time.

Popular manufacturers

There are many manufacturers of three-way valves on the domestic market. The choice of one model or another depends, first of all, on:

• type of mechanism (and let us remember, it can be mechanical or electrical);
• areas of use (DHW, cold water, “warm floor”, heating).

The most popular device is rightfully considered Esbe- a Swedish valve from a company that has been around for over a hundred years. This is a reliable, high-quality and durable product that has proven itself in many areas. Combination European quality and modern technologies.

Another popular model is the American Honeywell - a true brainchild high technology. Simple operation, convenience and comfort, compactness and reliability - these are distinctive features these valves.

Finally, relatively “young” but promising devices are valves from the Valtec line - the result of joint cooperation between engineers from Italy and Russia. All products are of high quality, sold with warranty period at seven years old. They differ in that they have a very affordable price.

How to install a mixing valve yourself

This installation scheme is used primarily in boiler rooms. heating systems, which are connected to a hydraulic separator or to a free-flow manifold. And the pump located in circuit No. 2 ensures the required circulation of the working fluid.

Pay attention! If the three-way valve will be connected directly to a bypass heat source connected to port B, then it will be necessary to install a valve with a hydraulic resistance equal to the same resistance of this source.

If this is not done, then the flow of working fluid will be segment A-B will oscillate according to the movement of the rod. We also note that this installation scheme provides for the possible cessation of fluid circulation through the source if the installation was carried out without a circulation pump or hydraulic separator in the main circuit.

It is not advisable to connect the valve to heating networks or a pressure manifold in the absence of devices that throttle excessive pressure. Otherwise, the fluid consumption per section A-B will fluctuate, and significantly.

If overheating of the return is allowed, excessive pressure is eliminated by means of a jumper installed parallel to the valve connection in the circuit.

How to install a dividing valve yourself

Providing quantitative regulation by changing fluid flow rates is the main function performed by such a three-way valve. Its operating principle is extremely simple and was discussed above. It is used where it is possible to bypass liquid to the “return”, but stopping circulation, on the contrary, is not allowed.

Pay attention! This connection scheme has gained wide popularity in water and air heating units that are connected from individual boiler houses.

In order to link hydraulic circuits, it is necessary that the consumer's pressure losses be equal to the losses at the balancer valve in the bypass. The diagram presented here is intended for installation on those pipelines in which there is excessive pressure. In this case, the liquid moves due to the strong pressure generated by a circulation pump.

Video - Three-way valve and its operating principle

A four-way valve is a plumbing element that performs important functions in a heating system.

Device and functions

The four-way heating valve rotates the spindle in the housing itself. Rotation must be carried out freely, because the bushing does not contain threads. The functioning part of the spindle has a pair of recesses, with the help of which the flow through two passes is opened.

Find out the price and buy heating equipment and related products you can find here. Write, call and come to one of the stores in your city. Delivery throughout the Russian Federation and CIS countries.

As a consequence, the flow is regulated and is unable to pass directly to the second sample. The flow can turn into any pipe that is located on the left or right side of it. It turns out that all the flows that pass from different directions are mixed and dispersed through four pipes.

There are devices where a pressure rod functions instead of a spindle, but such designs are not intended to mix flows.

A four-way valve for heating is an element of a heating system to which four pipes are connected, having a coolant of different temperatures. Inside the housing there is a sleeve and a spindle. The latter has to work with a difficult configuration.

The operation of a 4-way mixer can be controlled as follows:

1. Manual. In this case, to distribute the flows, it is necessary to install the rod in one specific position. And this position must be adjusted manually.
2. Automatic (with thermostat). Here external sensor gives a command to the spindle, as a result of which the latter begins to rotate. Because of this in heating system The specified temperature is maintained at a stable temperature.

Installation diagram of a four-way mixing valve in a heating system

The main functions of a 4-way valve are as follows.

1. Mixing water flows with different heating temperatures. The device is used to prevent overheating of a solid fuel boiler. The four-way mixing valve does not allow the temperature in the boiler equipment to rise above 110 °C. When heated to 95 °C, the device starts cold water to cool the system.
2. Protection of boiler equipment. The 4-way valve prevents the formation of corrosion and thereby extends the service life of the entire system.

Thanks to the 4-way valve for heating, a uniform flow of hot and cold coolant is achieved. For normal operation, no bypass installation is required, since the valve itself allows the required volume of liquid to pass through. The device is used where temperature regulation is required. First of all, in the heating system with radiators in conjunction with a solid fuel boiler. If in other cases the fluid is adjusted using a hydraulic pump and bypass, then in this case the operation of the valve completely replaces these devices. It turns out that the boiler functions stably and constantly receives a certain volume of coolant.

Manufacturers

Four-way valves for heating are produced by companies such as Honeywell, ESBE, VALTEC and others.

Honeywell's history began in 1885.

Today it is a manufacturer that is included in the list of 100 leading global companies compiled by Fortune magazine.

Honeywell 4 way valve

Four-way valves Honeywell V5442A series are manufactured for systems where the coolant is water or liquids with a glycol percentage of up to 50. They are designed to operate at temperatures from 2 to 110 ° C and at operating pressures up to 6 bar.

Honeywell manufactures valves with connection sizes of 20, 25, 32 mm. Therefore, the Kvs coefficient values ​​range from 4 to 16 m³/h. The series devices work together with electric drives. For systems with higher power, the flanged series of valves ZR-FA is used.

The Honeywell four-way valve will not cause any difficulties during installation; there are many implementation options.

The Swedish company ESBE has been setting new standards for the quality of valves and actuators used in various systems for more than 100 years.

All its products are economical, reliable and convenient to use in heating, cooling and water supply systems.

ESBE offers a 4-way heating valve with internal thread. The valve body is made of brass. Working pressure 10 atmospheres, temperature 110 degrees (short-term - 130 degrees). The four-way mixing valve is produced in sizes 1/2-2″, with throughput 2.5 -40 Kvs.

The VALTEC company appeared in 2002 in Italy and in a short time launched the production of products that were developed based on studying the pros and cons of products from various manufacturers.

Valtek offers mixing valves for various purposes, which are designed for durable operation in the engineering system (water-heated floor, built-in wall, ceiling heating and cooling, hot water supply). The manufacturer's products can be found anywhere in Russia and the CIS countries.

It cannot be said that a four-way valve for heating will not require financial investment. Installing the device will be expensive, however, on the other hand, the operational efficiency and, as a result, profitability, justifies the monetary costs. There is only one main condition - the availability of high-quality electrical network, since without it the valve drive will stop working.

2 way air conditioner service valve

3 way air conditioner service valve

4 way air conditioner reversing valve

The diagram shows the principle of operation of a solenoid valve in a refrigeration system (showing the direction of movement of the refrigerant when switching from the “heating” mode to the “cooling” mode and back).

4 way reversing valve designed to change the direction of refrigerant movement in a reverse cycle circuit. It should be noted that replacing a four-way valve in an air conditioner is one of the most difficult and expensive repair operations. It is comparable in cost to replacing an air conditioning compressor, because... requires several solderings per hard to reach places in close proximity to the valve body, overheating of which can lead to deformation and jamming of the internal fluoroplastic sleeve. Therefore, before talking about the defect check valve, it is necessary to check the serviceability electrical diagram, and that the reversing valve solenoid valve coil is energized (presence magnetic field checked by a characteristic click when removing and installing the coil). You should also ensure that there is sufficient refrigerant in the circuit and that the compressor is operating at full capacity.
We offer several options for solving the problem in the operation of this valve: actually replacing the faulty 4-way valve with a new one, replacing it with a unit with a 4-way valve assembly, or removing it. In the first case, the mandatory use of heat-removing paste and all-round access to the pipeline will be required. Therefore, this procedure for replacing a 4-way valve is practically impossible on a wall-mounted air conditioner and will have to be dismantled external unit during repairs. When replacing the assembly, the number of solderings is reduced to two and they are performed at a considerable distance from the valve body, which means that overheating is eliminated. In both cases, after repair, uninterrupted operation of the air conditioner in both heating and cooling modes is guaranteed. If it is possible to continue using the air conditioner in only one mode (either heating or cooling), then the faulty 4-way valve can be excluded from the hydraulic circuit, leaving the air conditioner to operate either cold or warm at the customer’s request. In this case, the air conditioner will work uninterruptedly without a 4-way valve, but its repair will cost much less than replacing it. Before carrying out work to replace the reversing valve, remove all refrigerant from the system, and after the repair, evacuate the circuit, install a new filter drier and charge it with freon.

Air conditioner valve check
(serves to ensure optimal pressure drop between the condenser and the evaporator when switching from the “heating” mode to the “cooling” mode and back)

Electronic expansion valve
designed for use in air conditioners and refrigeration systems, in heat pumps.
The valve supports automatic refrigerant flow settings and optimizes system operation for rapid cooling or heating, providing precise temperature control and energy savings. The valve can also be used, for example, to suck in pressure in a control line.
These valves provide bi-directional control of refrigerants, regulating flow rates in heating or cooling mode.

Thermostatic valve
The expansion valve is used to dose the amount of freon supplied to the cooler and is a throttle with a variable cross-section.
Connects after the filter, on the liquid line.
The thermostatic valve reduces the pressure and temperature of the freon so that when it enters the cooler, it boils off and effectively transfers heat. Special hole reduces the pressure of freon entering the expansion valve. The refrigerant coming from the condensing unit is a liquid, under high pressure. Passing through the expansion valve, freon turns into liquid dust, while its main parameters decrease. All these points improve the process of freon boiling away in the cooler.
The dosing of the amount of freon passing through the compressor-condensing unit occurs as follows: The expansion valve cylinder is in contact with the cooler manifold. There is freon inside the cylinder. When the freon temperature in the block increases, the refrigerant pressure in the expansion valve increases and the bellows stretches. The bottom of the bellows, through the rod, presses on the ball or needle, which, moving, increases the amount of freon passing through the thermostatic valve, while the temperature of the outlet tube and evaporator decreases. The freon pressure of the expansion valve drops, the bellows contracts, the ball closes the throttle, causing a decrease in gas volume.

Modern trends in the development of heating systems are increasingly inclined towards low-temperature floor and radiator systems, in which the coolant supply temperature is significantly lower than the temperature produced by the boiler. How to achieve flexible control of coolant temperature in conditions of constantly changing outside temperature?

For low temperature systems heating and “warm floor” systems need to be taken as follows technical solutions, in which chilled water from the return line is mixed into the supply pipe. This process is called high-quality regulation of the heating system, that is, regulation in which the coolant flow remains the same, but its temperature changes in the direction we need, and at the same time we do not interfere in any way with the operation of the boiler and its circulation pump. Quantitative control of the heating system differs from qualitative in that with it the temperature of the coolant does not change, but its flow rate changes, that is, a valve is simply installed on the pipe, the closure of which increases the hydraulic resistance and the circulation is slowed down or stops completely, and the coolant flow through the heating devices decreases accordingly.

High-quality regulation is carried out using a three-way valve and a bypass or a four-way valve located directly in front of the low-temperature heating ring (Fig. 26).

Rice. 26. Schematic diagram of high-quality regulation of coolant temperature

Turning the handle of the three-way valve to a certain position opens the bypass, and the circulation pump draws chilled water from the return into the supply, where it mixes with hot water submissions. Thus, the coolant supply temperature can be adjusted to the desired value. Three way valve can work very flexibly, it “knows how” to shut off the bypass or supply pipes or work to mix return chilled water with hot supply water. In other words, if the three-way valve closes the bypass, then the hot supply water completely enters the heating ring, if the valve closes the supply, then the heating ring works “on itself”, the coolant will spin in it through the bypass until it cools down, if the valve is open in the intermediate position, then the cooled water enters the tap through the bypass and mixes with the supply water, then it enters the heating circuit at the temperature we need. A three-way valve installed to regulate the temperature of the coolant, in this case, is called a three-way mixer (Fig. 27). The temperature of the hot water supply to the heating system can be adjusted manually using a scale on the mixer or using a temperature sensor and an electric servo drive.

Rice. 27. Three-way mixers

The use of four-way valves makes it possible to do without a bypass pipe, but these valves differ in operation: some, for example, with X-shaped valves, can only close and open the supply and return, but cannot mix water, others, for example, with rotary valves, water mix. When using taps with X-shaped dampers, hot water enters the heating ring and the tap closes, and the pump drives the coolant around the inner ring, as soon as the coolant cools down, the tap opens and a new portion of hot water enters the inner ring from the boiler, and the cooled water is discharged into the return line . Four way valve This design divides each circuit into two parts; its operation is reminiscent of adjusting the coolant temperature by turning a circulation pump on and off. But unlike pump regulation (turning the pump on and off), regulation here occurs in a softer mode, since the pump does not turn off and the circulation of the coolant does not stop. Of course, the use of four-way valves with X-shaped valves is only possible in automatic mode, since manually turning the valve every time the coolant in the internal circuit cools is simply impossible.

Rice. 28. Four-way rotary mixers

Four-way mixers with rotary dampers (and some others) provide a constant and equal flow of hot and cooled coolant and at the same time allow you to set the desired coolant temperature both manually and automatically (Fig. 28). Such a heating system does not require the use of a differential bypass; the mixer automatically passes the required amount of water, in other words, the total amount of water entering the heating system and water flowing back will be constant. The presented control system is one of the simplest: depending on the position of the valve, the four-way mixer allows a certain amount of water flowing from the boiler into the primary circuit; exactly the same amount of coolant is displaced into the return line.

Rice. 29. Example of a connection node solution " heated floors» and operation of the rod mixer

Typically, low-temperature heating systems are equipped with automatic controllers that measure the temperature of the coolant or the air temperature of the heated room, and issue commands to electric servos that “turn” the valves of three- or four-way mixers. In addition to rotary valve mixers, there are other control valves based on rod (Fig. 29) three- and four-way valves. Regulation (closing and opening of the mixer channels) occurs due to the lowering and raising of the rod with a cone valve. The mixer is controlled by a sensor based on the thermal expansion of certain materials, such as paraffin. A capsule with paraffin is placed on the pipe of the heating system; when heated from the pipe, the paraffin expands and closes or opens the thermocouple contacts, that is, the capsule works as a switch that transmits an impulse to a servo drive that moves the rod of a three- or four-way mixer. Then the temperature in the heating pipe decreases, the paraffin decreases in volume and opens the contacts - the mixer rod takes its previous position.

Rice. 30. An example of a heating system made according to the classical scheme

Thus, a heating system with a low-temperature underfloor heating circuit and a high-temperature radiator circuit may look like this (Fig. 30). The coolant, heating up in the boiler, enters the hot water collector, from where it is distributed over two distribution risers: radiator heating and “warm floors”. Radiator risers deliver water to the heating devices, where it is cooled and enters the chilled water collector connected to the boiler return pipe. The coolant, driven by the circulation pump, constantly circulates in this circuit and through the boiler. In the heating circuit of “warm floors”, a slightly different movement of the coolant occurs. Circulation pump pumps coolant from the supply manifold not constantly, but periodically, as the three-way mixer opens the supply. The rest of the time, the pump “spins” its own cooled water around the “warm floor” ring. It should be noted here that when manually adjusting a three-way mixer, the pump will constantly mix water from the supply manifold, and when adjusting the mixer automatically, two operating options are possible: with the “warm floors” completely disconnected from the boiler and with the addition of hot water. The fact is that manufacturers of three-way mixers produce two versions of these valves; in most cases, three-way mixers are configured in such a way that manually closing the valve, indicating “hot water supply is closed” on the device scale, does not actually completely close the hot water, but leaves it slightly open. This is the so-called foolproof protection. For example, having installed a radiator heating system with an error, the user completely cuts off the supply of “warm floors” to the heating system, while the boiler is running and heating water, pushing it into the system. And where should it flow if three way valve closed? The system creates overpressure and overheating of the coolant - a rupture of the boiler heat exchanger or pipeline is possible. A three-way mixer with a small hole, with seemingly complete closure of the supply, allows you to not stop the circulation and allow the coolant to flow through the low-temperature heating circuit.