What is 3-way thermostatic valve

When it comes to regulating heating water temperatures and distributing volume flows in the heating network, a three-way valve or a 3-way mixer is often used. The component has three connections, whereby it can mix two media or distribute one medium. How the three-way valve is constructed and when it is typically used is explained in the following sections.

Structural difference with the three-way valve

Although the task remains the same and the valve consequently always regulates the volume flow, the design can differ. Zone or switch valves with three ways are operated with the help of a 230 volt motor. This ensures that the valve opens and thus reaches the "open" operating state. If the voltage is removed from the valve, it closes again and, conversely, reaches the "closed" operating state. In practice, control is implemented via a relay contact within the control system. If the valve is in the "open" position, a transition from path A to AB can take place. In the "closed" position, it only allows a path from B to AB and the path from A to AB is closed.

Usually only used for the 3-way mixer for the heating circuit

Alternatively, a valve can also be operated via a servomotor with 230 volts. The control voltage varies between zero and ten volts and adjusts the valve accordingly as required by the heating circuit. The advantage here is that there is no such strict restriction between the individual routes and associated operating states, since the valve can be regulated in stages. As a rule, a 3-way mixer controlled by a servo motor is only used for the domestic hot water mixer for the heating circuit. Electrically operated control valves are usually installed in the return of the heating system due to the low temperature loads. If necessary, the contracted installer can provide you with details on your chosen heating system.

Why are 3-way mixers and valves required?

In a heating system, all components have to react perfectly to one another in order to ensure safety on the one hand and efficiency and faultless operation on the other. The three-way valve takes care of the necessary lowering of the flow temperature. In practice, such a valve or 3-way mixer is required when radiators and underfloor heating surfaces are in the same heating circuit. In this case, the valve mixes water from the return with the flow that is too hot for the floor heating. The flow temperature drops and both heating systems can be operated side by side without any problems.

Injection circuit with a three-way valve

Another example for the use of the component is the so-called injection circuit. This ensures that even consumers that are installed far away from the boiler can quickly access hot heating water. For this purpose, the 3-way mixer is located in the return line near the consumer. If this does not require any heat, it leads the hot flow directly back to the boiler. If the consumer device, for example an air heater, reports a need for heat, the three-way valve switches over so that the hot flow, supported by an additional pump, reaches the consumer.

Water heating and space heating

Furthermore, the procedure through the individual paths also allows the drinking water supply to be carried out separately from heating an apartment or a house. However, parallel use is also conceivable at the same time. It therefore enables permanent heating instead of having to set a priority switch between the domestic water and the heating of radiators. The three-way valve therefore primarily provides its users with flexibility and at the same time ensures more efficient operation of the entire system.

Prices are between 90 and 150 euros

3-way mixers and valves are available in various designs on the market. As a rule, you should expect a price of around 90 to 150 euros for a new purchase. Ideally, discuss the purchase with your contracted installer or tell them directly to buy one that matches the heating system. Among other things, the performance of the servomotor and the size of the valve must be taken into account. However, the expert is very familiar with these individual facets of the three-way valve.

In addition to the three-way valves, two-way valves are often used in practice. In practice, such a valve is required, for example, to either shut off or switch the circuits within the lines

Conclusion by Philipp Hermann

The three-way valve can mix or distribute media flows. With this function, it is used in a wide variety of areas today. For example, for the injection circuit, the regulation of flow temperatures or for the return temperature increase in wood boilers. In order to avoid mistakes when buying, the expertise of an installer is essential.

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