A three-way valve (also known as a three-way valve, mixing valve or sometimes a tee) is a solution commonly used in central heating and domestic hot water installations and in cooling systems. How does a three-way valve work? What is it responsible for in heating installations? Where is a three-way valve used? What are the types of three-way valves? Where should a three-way valve be installed – before or after the pump? And how can a three-way valve be set correctly so that the entire installation works efficiently and in accordance with individual preferences? Experts from the Onninen plumbing and electrical wholesaler answer key questions about three-way valves. We invite you to read and place orders.
Check out the three-way valves at the Onninen wholesaler
What is the three-way valve in the heating system responsible for?
The three-way valve is an important piece of hydraulic equipment. It has a characteristic, three-segment T-shaped structure. The construction scheme includes:
- body made of steel or brass,
- pin,
- a valve responsible for regulating the flow of liquid.
The three-way valve is available in various sizes (diameters). It is an integral part of the central heating system, especially those based on underfloor heating. When the heating device heats the water to a temperature higher than required by the underfloor heating, it must be appropriately lowered by mixing with water returning from the system. This is possible thanks to the installation of a three-way valve. Mixing hot and cold water allows for obtaining the optimal temperature for the heating circuit. The mixing takes place in the valve, hence its name: mixing valve.
A three-way valve also works well in heating systems, where the heating medium supplies both the central heating system and the domestic hot water supplied to the taps. It is also used in systems based on two heat sources, e.g. two different boilers, in order to use them according to current needs. In order to decide which device is to heat the domestic water and radiators, and which one is to supply heat to the underfloor heating, a three-way valve should be connected.
The three-way valve affects the efficiency of the heating system. First of all, it allows you to reduce fuel consumption and extend the life of the heating device. It protects the boiler from corrosion and the system from overheating. A special scale allows for precise, manual setting of the three-way valve.
Application of three-way valves
Depending on the type and individual needs, a three-way valve can perform various functions in installations. First of all:
- serves to lower the temperature in the heating circuit;
- allows you to use more than one heat source;
- protects the heating device against low-temperature corrosion;
- enables efficient distribution of water flow to radiators and taps;
- allows you to precisely set the hot water parameters (three-way thermostatic valve),
- preventing burns.
The three-way valve also works well with traditional radiator heating. Its installation allows you to avoid unhealthy and uncomfortable heat in the interiors - without the need to undesirably lower the set boiler temperature. The three-way valve ensures that the radiators are heated only to the temperature set on the scale. The effect? The stove is heated, so it works properly, and the rooms are not overheated.
The functionality of the three-way valve is extended by an actuator – a special electronic device connected to the heating device controller (e.g. an eco-pea coal or biomass boiler), which ensures automatic opening/closing of the valve depending on the boiler temperature. The three-way valve with an actuator is supervised by the controller, not by the user, which helps maintain an ideal temperature at all times, taking into account weather conditions. Weather control allows for optimisation of the combustion process. Automatic control can be not only electric, but also pneumatic or hydraulic.
Check out the three-way valves at the Onninen wholesaler
Types of three-way valves
There are two main types of three-way valves:
- three-way switching valves,
- three-way mixing valves.
The three-way changeover valve provides power to the circuits and allows you to change the fluid flow (direction) in the case of alternately used heat receivers. The changeover valve is commonly used in systems using more heating devices, e.g. a solid fuel boiler, heat pump and photovoltaics. Valves of this type have dual-function furnaces, used both for preparing hot water and for heating the building.
In turn, the three-way mixing valve, as the name suggests, ensures mixing of the heating medium with the medium returning from the system in order to obtain a suitably lower temperature. It is worth installing a mixing valve to effectively protect users of the domestic hot water system from scalding, better protect the boiler from low-temperature corrosion and maintain the optimal supply temperature of the heating circuit.
A variant of this type of valve is a thermostatic mixing valve, equipped with an automatic regulation of the degree of mixing. Thermostatic valves allow you to stabilize the temperature in installations responsible for transporting domestic hot water.
Three-way valves can be further divided according to the type of closing element. On this basis, they are divided into:
- three-way rotary valves , equipped with a valve element rotating around its axis by 90° or 180° - the extreme position allows the medium to flow through only one nozzle, while the intermediate position ensures mixing of the liquid flowing through two holes;
- three-way globe valves , equipped with a valve element moving in a linear motion, causing switching or mixing of the medium.
Correct setting of the three-way valve
You now know what a three-way valve is for and what its main types are. It's time to move on to setting! It is worth consulting a specialist with hydraulic experience when selecting parameters, because any errors can seriously affect the later operation of the boiler and the entire installation. It is generally assumed that the water returning to the heating device should have a temperature in the range of 50-60°C.
Depending on the type of three-way valve you choose, you will either set it manually or the flow rate and temperature will be configured automatically (in the case of the actuator version). When setting the three-way valve, it is absolutely necessary to follow the instructions and recommendations of the manufacturer of your product, and any universal information and tips found on the Internet should be treated only as a guide. If you are not sure how to set the three-way valve, call a plumber. It is worth investing in a modern, automatic three-way valve with an actuator .
Check out the three-way valves at the Onninen wholesaler
Installing a three-way valve before or after the pump?
Where should the three-way valve be installed - before or after the pump? This is a basic question that must be answered before installing three-way valves. You probably won't be surprised when we tell you - it depends. First of all, it depends on the specifics of the system in which this element is to be located. Most specialists solve this dilemma in the following way:
- Do you want to install a three-way valve in the heating circuit? Do it after the pump
- Does the DHW circuit require a three-way valve connection? Choose a location in front of the pump
Although installing a three-way valve is a task that should be handled by anyone with at least basic knowledge of hydraulics and heating system construction, if you have any doubts, you should consult a specialist. The plumber will select the appropriate installation location in the system and safely carry out the installation. After the installation is complete, the three-way valve still requires appropriate adjustment, as we wrote in the previous paragraph.
Finally, we have a few more practical assembly tips for you.
-
The three-way valve can be connected vertically or horizontally, depending on the intended location.
When choosing a mounting location, ensure easy access to this element, not only to ensure convenient operation, but also to facilitate maintenance and service work. - Water flow directions must match the indicator on the valve body.
- In open systems, a three-way valve (or any other!) must not be installed on the pipe leading from the boiler to the overflow tank or on the way to the expansion tank. The overflow tank is a safeguard in the event of a water temperature increase. It allows the heating medium to be drained outside the circuit. An increase in water temperature and pressure may, in extreme cases, lead to the bursting of the heating device.
- If your central heating system is not working properly, the cause may be an incorrectly installed or damaged three-way valve. The most common signs of failure of this element include: freezing and too low water temperature. If cleaning the valve does not help, call a specialist.
Three-way valves at the Onninen wholesaler
In the Onninen plumbing wholesaler you will find three-way valves in about 150 variants. We offer mixing and switching valves, manual and automatic. We only work with renowned manufacturers and suppliers of heating system solutions, such as Afriso , Danfoss and Esbe . In addition to three-way valves and other types of control valves, our range also includes drain, fill and safety valves and a wide range of accessories. All products have been carefully selected for their high efficiency, operational reliability and long service life. They offer an excellent price-quality ratio.
Need help selecting a three-way valve or other central heating system element? Contact us! After examining your needs, we will suggest products that perfectly meet the requirements of your project. Are you a heating system installer, service technician, boiler distributor or other professional? We invite you to cooperate! Business customers can benefit from unique benefits.