Three-way valve for underfloor heating regulation

How to choose

Underfloor heating. a modern heating system, the efficiency of its work is ensured by different devices, these include thermostatic valve.

When selecting a mixing unit, you should consider its flow capacity. It is necessary that it can process the water that is issued by the heating system. These data can be found in the technical documentation of the boiler.

For floor piping pipes are often taken in the size of 26 mm. The diameter of the thermostatic valve nozzles must match their size. Otherwise you need to install the adapter, which is not recommended, because the joints will be under constant pressure, and you need to monitor their tightness.

In addition, the equipment should be selected depending on the temperature of the coolant in the floor line, from 55 to 35 degrees.

If you choose from manual or automatic equipment, the presence of automation will facilitate the operation of floor heating, will create an acceptable microclimate in the house, and save the resource, but it is more expensive. Use of a programmable device will allow you to adjust the temperature depending on the time of day and day of week.

When installing water heating in a small room, you should not buy expensive equipment, a simple two-way valve will do.

When purchasing the appliance in a store, check the availability of the certificate, the warranty, and the manufacturer’s installation and operating instructions.

The main design features and functions of the device are

Having a rough idea of the principle of three-way valve operation, it is better to study the work of this mechanism in detail. The name “three-way” defines the main function of the device through two inputs into the valve water of different origin:

  • Hot coolant from the supply pipe associated with the heating device or with the riser of the central heating system;
  • Cooling water returned after the passage of the water circuit.
three-way, valve, underfloor, heating

Mixing with each other in a valve in a certain proportion, the flow goes through a third pipe, having a given temperature value. The valve operates continuously, since the cyclic operation of underfloor heating is based on mixing hot water with the cooled down heat transfer medium: heating and release of heat.sub-blend heat transfer sub-blend.

The mixing of two different flow temperatures must be monitored continuously, preferably in automatic mode. Otherwise, the intensity of heat exchange between the warm floor and the room air will not be tied to changes in the temperature in the room, and will have to manually change the temperature of the coolant heating as necessary.

Performing the mixing of the hot coolant in automatic mode allows the temperature-sensitive head, which adjusts the capacity of the valve, depending on the temperature of the mixed fluids to get at the output set point.

Depending on the purpose and operating conditions, different types of three-way valves are used.

For a heating system with radiators, operating from an independent boiler, the simplest type of device is used. Such three-way valves are inexpensive and have a relatively simple design that allows you to install them independently. Adjustment of the mixing volume in this case is done manually.

In systems of DHW three-way valves are used to maintain a system of communications safe water temperature values, eliminating the risk of scalding. The design of such devices is also quite simple and clear. From valves for heating systems, these devices differ in the presence of a special protective unit, blocking the hot water in the absence of cold water in the water supply.

Devices of this type are the most complex, as they are designed to maintain a given temperature of the coolant in heating circuits with reference to the temperature of air in the room. The use of such devices in the mixing node allows you to regulate the intensity of home heating in automatic mode,

Important! Using a three-way valve in the heating system requires the installation of a circulation pump to maintain the pressure in the water circuit required for the correct operation of the sub-assembly.

Layout of the mixing unit and location of the three-way valve in it

Model three-way valve with a scale

For underfloor heating, the valve is equipped with a regulating handle and measuring scale, with which to adjust the device.

Small areas of heating

If it is decided to carry out underfloor heating in a small area, the installation of full mixing equipment is not advisable. An alternative method of mixing can be selected.

Purchased special simple equipment for underfloor heating, consisting of a thermostatic valve with thermostat and two shutoff valves. The device is closed with a special box. The principle of operation of the equipment is as follows:

  • A special handwheel, located at the bottom of the valve, controls the temperature meter. It regulates the optimal base temperature.
  • A jump in the set temperature threshold serves as a command for the sensor. It closes the valve.
  • The design of the valve implies the presence of a sensor. It is able to track any temperature fluctuations in the atmosphere. If the set temperature threshold is exceeded, the sensor can close the valve.

This is how the product will work in conditions of a small heating area.

Is a three-way valve for underfloor heating necessary? The main function that is entrusted to the three-way valve

The heating system “water underfloor heating” is fundamentally different from the traditionally used by us, radiator heating. The fact that the heating circuits lying on the floor in the body of the concrete screed, requires a low temperature of the coolant. Underfloor heating is considered a low-temperature system, which is connected to the heating devices or the source of hot water through a mixing unit.

In order to provide heating in accordance with sanitary standards, it is necessary to significantly reduce the temperature of water entering the water circuits from the heating source. It is this function that is entrusted to the mixing unit or as it is commonly called among professionals, the mixing unit. Stand-alone boiler in the operating mode heats water to a level of 95 0 C. Water in the central heating system is slightly cooler. For the normal operation of underfloor heating the optimal temperature of the heating medium is 35-55 0 C, which is obtained at the outlet of the mixing unit.

Note: Do not confuse the mixing unit with the manifolds. The first represents a set of various assemblies and units providing regulation of water supply to the water circuit, while the second is just an integral part of the whole regulating unit.

The mixing node is a set of devices and devices that perform their specific functions. If the information about the collector is more, less enough, but what is the three-way valve, few of us have an idea. The task of this device is to mix the two different temperature streams of liquid. The cold water coming from the return pipe and the hot water coming from the heating source, through the work of this mechanism is combined into one flow, the desired temperature. The main part of this device is a thermosensitive core, an element that reacts to changes in the temperature of the aqueous medium by shrinking or expanding.

It is at the expense of this design, the work of the three-way valve, aimed at the automated regulation of the coolant temperature in the system.

On a note: this device is used not only in the work of the water underfloor heating, but also stands on the equipment of almost all self-contained heating systems, working on the liquid coolant.

The illustration shows a scheme of the mixing unit for the heated floors and the place of the three-way valve.

Floor heating mixer and location of the three-way valve.

The place and role of mixing valves in a floor heating system

The main task that consumers have to deal with, deciding on the installation of underfloor heating in their home, to achieve the desired temperature of the coolant. For radiators, the water temperature of 75 0 C is quite acceptable, which can not be said about the pipes that are laid in the thickness of the concrete screed.

Important! Excessive heating of concrete screed leads to a deterioration of the temperature balance within the heated room. Flooring (in most cases, wood-based) at high temperatures quickly loses its aesthetic and technological qualities, deteriorating.

According to sanitary regulations, the normal temperature of underfloor heating should not exceed 26 0 C. Then the middle layers of the air mass inside the room are heated to a comfortable 20-22 0 C. In order to obtain such temperature parameters, the water entering the water loop loops must be heated to 50 0 C. A little less than 50% of the thermal energy of the heated water is used to heat the puff cake of the floor heating. Taking into account the thickness of the concrete layer, the material and the type of flooring, the temperature on the floor surface decreases.

Achieve a significant reduction in the temperature of the boiler water at the inlet to the heating water circuits helps mixing unit, which is a set of interconnected devices and appliances. One of the main roles in the mixer is a thermo mixer valve, which mixes the water for underfloor heating. Thanks to this small device the two flows of water, cold and hot, are mixed so that the output water of the required temperature is obtained. Valves installed in mixing assemblies come in two types, three-way and two-way. Each of the valve types has its own, process-defined tasks and functions. Which device is best for your underfloor heating?? What’s behind the choice of mixing and regulating device type?

Types and their construction

In the thermostatic distribution valve installed on the floor heating, from the return pipe is mixed with the heated water of the cooled. This process is continuous as long as the heating is on.

Mixing valves for underfloor heating come in two-way and three-way. They also differ in the way they mix and the direction of flow.


Two-way thermostatic valve. an improved model of manual type. It can be hydraulic, pneumatic or electrically operated.

The design is simple, but capable of effectively regulating the temperature level of the heating medium in automatic mode. The device is installed in the heating system, instead of the manual valve.

The disadvantages. the possibility of its installation on the small pipelines. If you use this faucet in the arrangement of the heating in the room with a large area, the thermostat will operate intermittently. Two-way valve more often used when underfloor heating acts as additional heating.

The valve design is a brass or bronze body, with one or two seats. Two-way valve can completely cut off the water supply.

Regulation of heating OVENTROP three-way valves.

The device is equipped with a temperature regulating head with a scale. The head position can be changed manually or automatically. The manual models are simple and inexpensive. modern devices actuate automatically.

Two-way valve operates on the following principle. the coolant from the return flow is fed back into the floor pipes, but before that, the device opening the supply of hot water is triggered. The two flows mix inside the body to the desired degree, then the temperature sensor is triggered and the valve automatically closes the opening with the hot coolant.

It consists of a plug and seat. The plunger has a disc, needle or bar form. It is perpendicular to the fluid flow.

Three-way valve

The principle of operation of the three-way thermostatic valve for underfloor heating. hot water coming from the boiler is mixed with the cooled water from the return flow.

The valve is designed for heating systems that are installed in large rooms. They have the same advantages as two-way valves. Particularly worth noting is the ease of temperature adjustment of water for underfloor heating.

But this thermostatic valve has a disadvantage. if the thermostat is triggered, the valve opens fully, thus the hot coolant flows into the circuits. And that can cause overheating of the heating system, and even bursting of pipes. In addition, it has a lower flow capacity than a two-way valve.

Three-way thermostatic mixing valves come in brass and bronze. They are equipped with a thermostatic head or thermostat, can have an electric actuator or servo. Design. a valve with two inlets and outlets. Inside the body there is a mixing chamber, it has a thermostat with a regulator, which has a digital panel. The thermostatic valve is connected before the manifold.

The principle of operation of the three-way thermostatic valve:

  • the heated water moves along the right and front pipes. if its degree of heating corresponds to the required parameters;
  • If the temperature of the liquid rises or falls, the thermostat is set in operation, it moves the stem, as a result of which the hot water is mixed with the cooled water;
  • after reaching the set temperature, there is a full opening of the front opening.

It should be said that when the device is turned on, the water flow voltage does not change. This leads to an even change in the temperature of the liquid flowing into the mains.

Features of the three-way valve

Mixing of liquid streams, which allows the thermostatic mixing valve to perform, makes it possible to direct the flow into the floor heating system with a stable, normatively set temperature. This operation is done automatically. To mix, occurring inside the device, to the hot water is added already cooled liquid from the “return”.

Functioning occurs in the following sequence:

  • The hot water flows to the manifold which is part of the underfloor heating system;
  • the passage of the thermostatic mixing valve determines the degree of heating of the liquid;
  • if the water temperature is higher than the set temperature, a passageway opens where the chilled fluid enters
  • inside there is a mixing of the two flows;
  • after reaching the desired value, the cold water passage closes.

Among the disadvantages of three-way valves is the possibility of sudden temperature jumps that occur during the start of heated water, which negatively affects the condition of the pipeline.

Supply and heat treatment in the floor of the three-way mixer

Such a valve, made of brass, in its design has three moves, resulting in the use of different ways of mixing the liquid flows, depending on which there are three varieties of three-way valves.

Overall and installation dimensions of three-way valve

  • Valve with the right thermostat function for underfloor heating. Such a device not only regulates the intensity of mixed streams, but also provides maintenance of the set temperature in the system. This function is assisted by the thermal sensing element, which, by sensing the degree of heating of both flows entering the valve, changes the cross-section of the openings.
  • Three-way thermostatic valve of the second type differs in that it only regulates the intensity of hot flow. Includes a thermostat head with a remote sensor.
  • You can also choose from a range of three-way models a mixing valve that does not automatically maintain the set temperature.

By the method of mixing

Depending on the mixing method, there are underfloor heating taps:

  • with thermostat function. it can achieve and hold the desired degree of coolant temperature, because the device is able to regulate both flows (cooled and heated). The thermostat in the mixer reacts to the level of heating of the liquid, produces opening or closing of the hole, through which the heated or cooled coolant is supplied. In addition, the mechanism is designed so that in the absence of cold water, the automation cuts off the flow of hot.
  • Thermostatic. the device is equipped with a sensing thermal head having a remote temperature sensor, it is placed in each main. The work of the valve is to determine the water temperature, and giving the command to the actuator.

Gas or liquid

The efficiency of the thermostatic valve depends on the properties of the substance in the bellows. Gas filled thermocouples are more accurate and reliable. They respond faster to temperature changes, but are more complex to produce and therefore more expensive.

Liquid ones are a little slower to act, but easier to fabricate. One of the advantages of liquid temperature control elements is the high transmission accuracy of the internal bellows pressure to the thermostatic valve stem.

With remote sensor

Thermovalves with remote sensor are designed for installation in radiators with bottom connection or located in a recess. The thermostatic head is mounted on the valve using a threaded connection and the temperature sensor is mounted on the wall in any convenient location. Head and sensor are connected by capillary tube.

Such models maintain the temperature more accurately, but at a higher price than others.

Three-way valve for heating with a thermostat: scheme, varieties, necessity of application

Comfortable temperature of the living space. the main task of heating. But not everyone thinks that in addition to the main nodes, units (boiler, radiators, circulating pump) for heat are also responsible for less visible devices. One of them is a three-way valve for heating with a thermostat, the scheme of which is not complicated, but requires careful, detailed consideration. Such nodes are found today in every apartment or private home. In today’s review, let’s analyze the principle of operation, design and functions of this element. At the same time we will consider the nuances of the installation and the cost of various models in the Russian market.

The purpose of the valve for the underfloor heating and its types

Design auxiliary heating system may include the installation of two-way or three-way valve for underfloor heating in the mixing unit. Both ensure continuous thermal regulation of the liquid heat carrier. The water floor can be connected to both centralized and autonomous heating. In both types of systems the temperature of the liquid coolant is 650C-850C. If so hot water gets into the floor heating circuits it is not possible to create a barefoot comfortable walking and sitting atmosphere on the floor covering surface.

A floor screed is a great accumulator of heat, so that the floor surface will have a temperature above 450°C. Which is not safe for the flooring itself. The admissible surface temperature must range from 180C to 330C. To ensure these conditions, it is necessary to cool the heated liquid before running into the circuits of the system. This procedure is carried out by a mixing valve for underfloor heating, which can be purchased in specialized stores.

If you can’t do without them in auxiliary heating systems, then which one to choose. two- or three-way? It is very easy to determine:

  • The supply, or two-way valve for underfloor heating is a simpler, and therefore more stress-resistant device. Its installation will not overload the system. The device takes care to avoid sudden and unstable release of flow. It is used in systems of heating of air masses from beneath the premises of small scale (maintenance of the area no more than 190 m2). In this case, the high-temperature heating system must provide heating of the liquid heat carrier exclusively for the circuits of the warm water system. In essence, a two-way thermostatic valve for underfloor heating performs the temperature increase of the coolant, performing the mixing of hot fluid coming from the boiler, to the cooled, coming from the return.
  • Structurally more complex three-way valve for underfloor heating. a device that performs the function of mixing the hot and cooled streams, and then issuing. Suitable for floor heating systems larger than 200 m2 and when connecting the water floor heating to a centralized or autonomous heating network. Its principle of operation is described above.
three-way, valve, underfloor, heating

Since the three-way mixing valve for underfloor heating (called thermostatic, thermostatic mixing valve) is a versatile device, it is used in 8 out of 10 cases. However, if the device is installed incorrectly in the system, accidents can occur.

Manufacturers of three-way devices

There is a wide range of three-way valves on the market, both from reputable and unknown manufacturers. The model can be chosen after the general parameters of the product have been determined.

The first place in the sales rating is occupied by valves of the Swedish company Esbe. This is a fairly well-known brand, so the three-way products are reliable and durable.

Among consumers known for its quality three-way valves Korean manufacturer Navien (Navien). You should buy them if you have a boiler of the same company.

Greater accuracy of regulation is achieved by installing a device made by the Danish company Danfoss. It works fully automatically.

Valtec valves are of good quality and affordable price, made by Italian and Russian specialists.

Efficient in the work of the company’s products from the U.S. Honeywell. These valves have a simple design, easy to install.

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