Three-way mixing valve Termojet, DN25, kvs-10 female thread

The Termojet DN25 three-way rotary mixing valve is a fitting with a rotary plug and internal thread Rp 1" for automatic control of the heating medium supply temperature. Flow coefficient Kvs 10 m³/h, working pressure PN 10 bar, temperature range –10…+110°C. Brass body CW617N, EPDM seals, leakage less than 0.1%. The standard actuator mounting allows installation of 401N, 405N or 411 series actuators without additional adapters.

Technical Specifications

Operating Principle

The valve has three ports: A — hot heating medium from the boiler or heat pump, B — cooled return from the circuit, AB — mixed supply to the heating circuit or underfloor heating. When the plug rotates in the range of 0–90° following the actuator signal, the share of each flow changes proportionally — the temperature at outlet AB is regulated smoothly and steplessly. The linear flow characteristic at Kvs 10 ensures accurate dosing across a wide load range. Leakage in the closed position is less than 0.1% of Kvs.

Applications

• Underfloor heating in medium and large buildings. DN25 Kvs 10 is optimal for mixing units of floor circuits with an area of 100–180 m²: maintains supply temperature of 35–45°C in any boiler operating mode.
• Mixed systems — radiators + underfloor. A separate valve for the underfloor heating circuit in systems where radiator branches operate at higher temperatures.
• Weather-compensated control. Combined with the 411 actuator (0–10V, 24V) and a weather-compensated controller, the valve smoothly reduces supply temperature as outdoor temperature rises — real energy savings.
• Boiler room with multiple circuits. DN25 Kvs 10 is the standard choice for systems with a capacity of 20–50 kW with several independent heating zones.
• Manual balancing. Without an actuator, the valve can be locked at any rotation angle for static thermal balancing of the system.

Advantages of Termojet DN25

• Kvs 10 at DN25 — high flow capacity for medium and high-output systems without moving to a larger DN.
• Brass body CW617N — precision and corrosion resistance comparable to leading European valve manufacturers.
• Leakage less than 0.1% — minimal uncontrolled heat loss through the plug in the closed position.
• Standard actuator mount — installation of Termojet actuators without adapters or additional parts.
• EPDM seals — resistance to heating media with glycol and elevated temperatures.

Compatible Actuators

The plug torque of the Termojet DN25 valve is less than 3 Nm. All actuators listed below have a twofold torque reserve (6 Nm):

• Termojet 401N actuator (3-point, 230V, 120 s) — for boiler controllers with a 3-position output, the standard solution for most schemes.
• Termojet 405N actuator (3-point, 230V, 60 s) — reduced travel time for systems with lower thermal inertia.
• Termojet 411 actuator (0–10V, 24V) — for weather-compensated automation, smart home, and heat pump systems.

Valve and Heat Pump

A heat pump operates most efficiently at low heating medium supply temperature. The Termojet DN25 Kvs 10 three-way mixing valve combined with the 411 actuator (0–10V) and a weather-compensated controller maintains the optimal supply temperature of 35–40°C in the floor circuit — even if the heat pump delivers 45–50°C. This directly increases the system COP and reduces electricity costs. More about integrated solutions — on the Termojet heat pumps website.

Frequently Asked Questions

What is the difference between DN20 Kvs 6.3 and DN25 Kvs 10 in the same heating system?
A larger DN and Kvs means lower hydraulic resistance at the valve for the same flow rate. Choose DN25 Kvs 10 for circuits with a heating medium flow rate above 4 m³/h or systems with a capacity of 30–35 kW and above. DN20 Kvs 6.3 is sufficient for smaller systems and floor circuits up to 80–90 m².

Is the DN25 valve compatible with actuators from other manufacturers?
Termojet valves have a standard actuator mounting seat. Compatibility is ensured by a 90° rotation angle and flange size. Termojet 401N, 405N and 411 series actuators are the verified option without additional adapters. For actuators from other brands — check the mounting diameter and torque at installation.