Three-way mixing valve Termojet, DN40, kvs-18 male thread

Termojet DN40 three-way rotary mixing valve — a fitting for high-capacity heating systems with external thread G 1 1/2". Flow coefficient Kvs 18 m³/h, working pressure PN 10 bar, temperature range –10…+110°C. Designed for boiler rooms of 60–120 kW, large underfloor heating circuits, and systems with high heat-transfer fluid flow rates.

Technical Specifications

Operating Principle

Three ports: A — hot supply from the boiler, B — return from the circuit, AB — outlet to the heating circuit. When the ball rotates 90° on the actuator's command, the mixing proportion is regulated steplessly — the temperature at outlet AB varies from the boiler temperature to the return pipe temperature. Kvs 18 provides minimum hydraulic resistance at high heat-transfer fluid flow rates in high-capacity systems.

Applications

• Boiler rooms of 60–120 kW. DN40, Kvs 18 — the standard choice for large private boiler rooms, cottages, and small commercial and industrial facilities.
• Large underfloor heating circuits. Underfloor heating area of 250 m² and above — Kvs 18 provides the required flow rate without pressure drop.
• Systems with multiple manifolds. DN40 as the main mixing unit ahead of a distribution manifold serving several branches.
• Weather-compensated control in large systems. With the 411 (0–10V) actuator — smooth analogue control of supply temperature depending on outdoor temperature.
• Industrial and agricultural facilities. Production workshops, greenhouses, warehouses — where high flow rates at moderate fluid temperatures are required.

Advantages of Termojet DN40

• Kvs 18 — for systems up to 120 kW: sufficient flow without excessive hydraulic resistance.
• CW617N brass body — corrosion resistance and long service life under demanding operating conditions.
• Ball torque below 5 Nm — compatible with standard 6 Nm actuators.
• EPDM seals — resistance to glycol heat-transfer fluids and temperatures up to 110°C.
• A worthy replacement for imported DN40 valves with equivalent Kvs — without pipeline rework or customs delays.

Compatible Actuators

For DN40 Kvs 18, actuators with a smooth stroke are recommended to prevent hydraulic shocks:

• Termojet 405N actuator (3-point, 230V) — the standard choice for boiler rooms with a 3-position controller.
• Termojet 411 actuator (0–10V, 24V) — fully smooth analogue control for weather-compensated controllers and smart-home systems.

Valve and Heat Pump

In large systems with a heat pump and underfloor heating of 250+ m², the Termojet DN40 Kvs 18 valve provides the required heat-transfer fluid flow at a supply temperature of 35–45°C without hydraulic restrictions. Paired with the 411 (0–10V) actuator — proportional control that coordinates with the heat pump control algorithm. More details — on the Termojet heat pumps website.

FAQ

How to choose between DN32 Kvs 12 and DN40 Kvs 18?
DN32 Kvs 12 is sufficient for capacity up to 60 kW and floor area up to 200 m². Choose DN40 Kvs 18 for a boiler room capacity of 60–120 kW or a high heat-transfer fluid flow rate. If the calculation shows a required Kvs above 12 — DN40 is the next step. For comparison — DN32 Kvs 12.

Is DN40 suitable for a standard 6 Nm actuator?
Yes. The ball torque of the DN40 valve is below 5 Nm. The 405N and 411 actuators have a torque of 6 Nm — a sufficient margin for reliable operation.