Four-way valve - what is it used for and how does it work?

What is a four-way valve used for?

The four-way valve (a.k.a. four-way valve) has several functions:

• protects the boiler from too low a return temperature;
• allows to regulate the temperature of water in the heating system;
• allows mixing water from the supply with water from the return;
• can direct water to different consumers (e.g., radiators and DHW tank).

It is most often used in installations with solid fuel boilers, where it is important to maintain a minimum temperature of water returning to the boiler (usually about 55°C) to prevent condensation and corrosion.

Principle of operation of a four-way valve

The principle of the four-way valve is to mix two streams of liquid - hot from the supply and cool from the return. The valve has four spigots:

1. supply from the boiler (hot water),
2. outlet to the heating system,
3. return from the system,
4. return to the boiler.

By rotating the internal element (usually with a knob or actuator), the user can adjust the mixing ratio of hot and cool water. In this way, the valve is able to:

• heat the water returning to the boiler (which prolongs its life);
• lower the temperature of water flowing into the heating system (which increases comfort and protects system components);
• stabilize the operation of the entire system.

In practice, the operation of the four-way valve depends on the setting of its knob (or the position of the actuator):

• when fully open: most of the hot water goes into the system, and the return flows directly to the boiler;
• at the mixing setting: some water from the supply goes to the return, raising its temperature;
• when closed: circulation is mainly through the valve, without supplying the system (e.g., when starting the boiler).

With this design, the valve can regulate both the temperature of the system and the operating conditions of the boiler.

How this valve works

In a simple 4-way valve scheme, the flow from the boiler enters one of the valve chambers, and there, depending on the setting, it partially mixes with cool water from the system and is directed further into the circuit. At the same time, the water returning to the boiler is partially heated by the water from the supply.

A mixing scheme is most often used to keep the return water temperature stable, preventing temperature shocks and condensation.

Where to mount a four-way valve?

It depends on the type of installation and its function. In practice, this valve is most often installed on the boiler supply and on the return from the system, in the immediate vicinity of the boiler. Such a solution provides effective protection against cold water return, which protects the heat exchanger.

Another popular place of installation is the section in front of the installation manifold, especially when the valve also performs the function of distributing the flow of heating medium to several circuits.

The four-way valve can also be installed before the hot water cylinder, if its function is to control the direction of flow between the heating system and the cylinder.

Want your heating system to run longer, more efficiently and more safely? The four-way valve is a proven solution that helps achieve just that. A well-chosen and correctly set valve means not only greater thermal comfort, but also savings on boiler servicing.

FAQ

**1. Can the four-way valve be used in heat pump installations?

The four-way valve is mainly used in systems with solid fuel boilers. In the case of heat pumps, there is usually no need to protect the return from too low a temperature, so this valve is not a standard component of such an installation.

**2. What is the difference between a four-way valve and a three-way valve?

The three-way valve has three spigots and is mainly used to mix or distribute the flow in one circuit. The four-way valve has four spigots and allows simultaneous mixing and temperature control of two circuits - supply and return.

**3. Does a four-way valve always require an actuator?

No, the valve can also operate in a manual version. The electric actuator is mainly used in systems with weather automation or in installations that require precise and dynamic control.

**4. How often do you need to adjust the four-way manual valve?

In installations without automation, the valve should be adjusted seasonally - adjusting its setting according to external temperatures and heat demand. In practice, 2-3 adjustments per year are sufficient: at the beginning of the heating season, during and at the end.