Advantages and disadvantages
Advantages of three-way mixing valves:
- Simple design.
- Stable regulation.
- Reliability.
- Tightness.
- Sufficient regulation accuracy (maximum accuracy up to 1°C).
- Durability.
- Relatively compact dimensions.
The biggest advantage of using three-way valves. pipes and respectively screed and floor coating do not overheat, which prevents premature failure of the screed and coating.
- The hydraulic resistance of three-way designs is higher than that of conventional two-way valves.
- Design of the body and spool allows the presence of stagnant zones. periodically will have to dismantle the device and clean from scale, debris, organic impurities.
- Lack of precision in regulating the room temperature. The control valve regulates rather precisely only the temperature of the heating medium leaving the room, and the temperature of the heated room. approximately.
To ensure a comfortable level of heating, you will have to select the ratio of the temperature of the outgoing flow to the temperature in the room “by gut feeling”. Unfortunately, the underfloor heating pipes are much larger than the radiator, and accurate regulation is impossible. It is even more complicated by the inertia of the floor heating. 100mm cement screed heats up very slowly.
But if you tolerate slow heating or cooling of a room, the valve with mechanical regulation is suitable for use in a heating system of a private house or apartment.
Much more comfort is provided by electrically actuated valves controlled by a “smart home” system with temperature sensors in each room. But these devices are very expensive.
Three-way valves are subdivided according to their operating principle. There are mixing and isolating valves. In systems of a warm floor (and in radiators) the mixing devices which adjust temperature of an outgoing coolant by mixing of cold and hot water are applied.
According to the method of actuation three-way devices are:
- Manual. Very rare and inexpensive. Handy if the floor heating is installed in 1 or 2 rooms. such as a bathroom and a nursery.
- Automatic.
In manual actuators, the stem position and outlet water temperature adjustment are adjusted manually by means of a knob. In the automatic ones, the movement of the plunger is controlled by either a thermostatic head or an electric motor controlled by an automated system with temperature sensors.
- The simplest type with thermostatic head. Actuated by increasing temperature (responds to increasing pressure). These devices are used for radiators. Liquid in the actuator expands when the temperature rises and actuates the stem.
- With thermostatic head and remote sensor.
- Electrically actuated. The plunger is actuated by an electric motor. The motor is controlled by a controller, which receives signals from temperature sensors. The actuator can operate the valve with a solenoid (magnet) or mechanical transmission (servo drive).
- In production systems with large pressures and diameters pneumatic or hydraulic actuators are used.

Get a superficial idea of what work performs the three-way mixing valve, and how significant is its role in the mixing unit, allows any scheme of warm water floors, regardless of the number and configuration of circuits. For better orientation while choosing this device let’s understand in detail what this component is, and what its principle of operation is.
Two-way
What it consists of
Two-way valve for underfloor heating is a device that limits the access of hot flow into the system of underfloor heating pipes. It blocks the opening of the channel conducting the hot direct flow by a certain value, reducing within certain limits its flow or, conversely, increasing it to raise the operating temperature. In fact, a two-way valve is an ordinary valve, as it is sometimes called.
Attention! Strictly speaking, a two-way valve is not exactly a valve in the full sense of the term, however, the established terminology prefers this designation of the device.
How it works
Two-way valve is installed in the gap of a direct main pipeline and sets a certain mode of feeding the hot water to the working mixture. For a simplified picture of its action, consider the action of a hot valve in a faucet. the temperature of the water coming out of the faucet depends on the amount of opening.
Approximately the same works two-way faucet, the only difference is that the mixing is not two separate, but the same flow, which has a difference in temperature in different areas.
How to choose
Installing underfloor heating, even in a detached house, is a rather complex engineering system with ambiguous results. With poor regulation all the benefits can disappear, so you can not save on the manifold node and control valves. Good three-way valves are not cheap, on the market or on the Internet there is a high probability of purchasing low-quality products.
For a floor heating system is better to buy equipment in a hypermarket or specialized stores. The certificate should be obligatory! Or a passport with a “wet” stamp and filled out warranty. The receipt should be kept.
Usually buy products made of brass. Stainless steel valves are more expensive and less common. Silumin is not even worth considering. products made of it poorly tolerate constant opening-closing, and the regulatory fittings are worth a lot.
When buying in the store to inspect the valve. that there were no chips, cracks, jams. It is necessary to try to look inside the valve. on uncoated brass products the inside should be goldish (not white-silver like silumin). You can orient by weight. Silumin products weigh much less than brass ones. the density of brass is about three times that of silumin.
Popular manufacturers
In first place in quality. products of Swedish company ESBE. The firm has been producing tube fittings for more than one hundred years. The second place is occupied by American company Honeywell. Valves of firms HEIMEIER, HERZ, Navien, Danfoss, Mut, Oventrop, Siemens. The price of these products is more than the quality. reasonable price in products of joint Italian-Russian manufacturer Valtec.
Two way control valves
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How the thermostatic valve for underfloor heating works
Not so long ago, underfloor heating belonged to the luxury goods. Nowadays, it has become clear that this option of heating is the most preferable to create an ideal microclimate in the room. When simply installing radiators, warm air immediately rises, leaving the floor completely cold. The result is a departure from the standards at which temperature readings would be favorable to humans. In this article we will talk about the three-way valve for underfloor heating, describe its characteristics and types.
What materials are made of
Now common cast iron, brass and steel products. For example, valves made of cast iron and steel are installed in pipeline systems with a large flow of water or steam. Brass valves are often found in ventilation systems. Their main advantage. compact size, so the element is installed even in small rooms, with limited water flow.
We recommend the use of a steel or cast iron control valve. Products made of steel are common, which are as durable as their cast iron counterparts, but much cheaper. When selecting the material, the characteristics of the pressure in the system and the size of the valve itself are taken into account.
Steel valve
Thermostatic valve for underfloor heating: types and device, how to choose, installation diagrams and alternative ways of connection
The water from the boiler flows through the pipe network to the collector. From there, the fluid flows into the floor piping. After releasing heat, it returns back to the manifold, which has a separate return outlet for the cooled coolant. The circulation pump presses the water back into the boiler.
When manually controlling the temperature mode on the circuit with cold water and high temperature coolant set valves. When the room is warm enough, close the hot water valve. If the room is cold, the valve opens.
For automatic control of heating install three-way mixer with a thermostat and remote thermostat sensor. This system forms a thermostatic valve. It is installed at the inlet to the manifold. The equipment is made of brass or bronze.
- The three-way valve has 3 outlets for hot water, cold water and for coolant, which is fed into the floor line. Markers on the housing indicate the direction of flow of different temperatures.
- A mixing chamber is provided for mixing liquids of different temperatures.
- On the housing there is a thermostat, with temperature regulator.
- The temperature sensor is located on the thermostat.
- The valves shut off the outlets for hot and cold water. They can be poppet or needle. Their operation depends on the thermostat.
- The thermostat is a system that consists of a capsule with liquid and a spring-loaded stem. The valves are attached to it.
- The temperature sensor has a digital panel on which the heating modes are marked.
The thermostat can be located in the thermostat head or in the actuator. The devices have different circuitry, but the principle of operation is the same. The thermostat is a thermostat, which is operated by a liquid: it is sensitive to temperature changes.
The actuators are powered by electricity. The liquid is enclosed in a tank. It contains a heating plate. The actuator is installed on the manifold.
Three-way mixer designed for heating systems of large areas. In individual rooms or summer cottages a two-way valve is connected to the manifold. It is attached to the high-temperature fluid circuit. Water flows through it only in one direction.
Equipment characteristics
Coolant from the boiler flows through the pipe line to the manifold. From there the liquid flows into the floor heating pipe. After releasing heat it flows back to the manifold, which has a separate return flow for the cooled medium. A circulation pump presses the water back into the boiler.
For manual control of the temperature mode, the valves are installed on the cold water and high-temperature heat carrier circuits. When the room is sufficiently warm, the hot water valve is closed. If the room is cold, open the valve.
For automatic control of heating install a three-way mixer with a thermostat and remote temperature sensor. This system forms a thermostatic valve. It is installed at the inlet to the manifold. The equipment is made of brass or bronze.
- The three-way valve has 3 outlets for hot water, cold water and for coolant, which is fed into the floor line. Markers on the housing indicate the direction of the various temperature flows.
- A mixing chamber is provided for mixing fluids of different temperatures.
- On the body there is a thermostat, with a temperature regulator.
- The temperature sensor is located on the thermostat.
- Valves close the outlets for cold and hot flow. They can be disc-shaped or needle-shaped. Their function depends on the thermostat.
- Thermostat is a system that consists of a capsule of liquid and a spring-loaded stem. Valves are attached to it.
- The temperature sensor has a digital panel on which the heating modes.
Recommended: How to choose a wire for underfloor heating?
The thermostat can be located in the thermostat head or in the servo drive. The devices have a different circuitry, but the principle is the same. The thermostat is a liquid thermostat: It is sensitive to temperature changes.
Servo actuators operate from the mains. The fluid is contained in a tank. It contains a heating plate. The actuator is installed on the manifold.
Three-way mixer is designed for heating systems of large areas. In individual rooms or holiday homes, two-way valves are connected to the manifold. It is installed on the contour with a high temperature coolant. Water flows through it only in one direction.
Quantitative temperature control of underfloor heating
Distribution comb or manifold is a node that ensures the correct operation of the floor heating system. In this case, the coolant is not necessarily distributed evenly across the circuits, but according to the set modes. A heating manifold is required if there are more than two. The ratio of heat carrier flows is set on each circuit thermostatic head for underfloor heating.
The simplest way is to quantitatively regulate the temperature of the underfloor heating, through the change in the flow of the coolant. The flow to each circuit is controlled by a RTL thermostatic head for underfloor heating. It maintains a set water temperature at the outlet of each loop. The sensor is a bellows filled with a temperature-sensitive fluid. The position of the valve head depends on its temperature and the setting of the outer cover with scale.
The thermal head for underfloor heating senses the air temperature in the room and depending on its value and the manual setting of the maximum heating of the heating medium. The upper and lower level of the control range is limited by the locking clamps.
UNDERFLOOR HEATING GUIDE AND INSTALL PART 2. Plumbing Tips
The model can have internal or external threads, with which it is screwed to the pipe.