Two-position actuator Termojet 230 V, 2P+AUX (60 sec.) 412N

Termojet 412N actuator — a two-position motorized actuator for zone and control valves in heating and air conditioning systems. Supply voltage 230V AC, control type — 2P+AUX (two-position with auxiliary contact), actuation time — 60 seconds. The AUX auxiliary contact allows sending a boiler or pump start signal only after the valve has opened — the standard scheme for zone heating systems.

Technical Specifications

Operating Principle

When 230V AC is applied to the actuator input, the valve gate opens. Once the open position is reached, the AUX auxiliary contact triggers — it sends a start signal to the boiler or circulation pump. This ensures that the boiler only starts working when the valve is already open and the heat carrier can enter the zone. When the voltage is removed, the actuator returns the gate to the closed position, AUX opens — the boiler or pump receives a stop signal. 2P+AUX is the standard scheme for zone systems «thermostat → valve → boiler».

Applications

• Zone heating 2–4 zones. A separate 412N actuator for each zone — the room thermostat controls the zone independently. The boiler starts only when at least one zone is open (via AUX).
• DHW priority. The actuator opens the valve on the boiler circuit — AUX sends a signal to the boiler. After the boiler heats up, the thermostat removes voltage, the valve closes, and the boiler switches to heating.
• Radiators + underfloor heating as independent zones. The 412N actuator controls the zone valve of each circuit from a separate thermostat.
• Automation with a weekly programmer. The programmer applies voltage to the actuator on a schedule — the zone opens and closes automatically.

Advantages of Termojet 412N

• AUX auxiliary contact — standard scheme for starting a boiler or pump on a valve-open signal without additional relays.
• 230V AC — direct connection from a thermostat or programmer without a transformer and additional power supplies.
• Two-position control — the simplest possible wiring scheme: phase from thermostat to actuator.
• Actuation time 60 s — sufficient for standard zone valves without water hammer.
• A worthy replacement for two-position actuators of equivalent frame size — without rewiring.

Compatible Valves

The Termojet 412N actuator is compatible with rotary valves with a 90° stroke angle. For zone systems, use together with:

• 3-way mixing valve DN25 (internal thread)
• 4-way mixing valve DN32 Kvs 18
• Termojet valves and actuators — full catalogue

Actuator and Heat Pump

In systems with a heat pump, the two-position 412N actuator is used for zone switching between the DHW circuit and the heating circuit. The AUX contact sends a signal to the heat pump to change the operating mode after the corresponding valve has opened. If your heat pump requires an analogue control signal — consider the 411 actuator (0–10V, 24V). More details — on the Termojet heat pumps website.

Frequently Asked Questions

What is the AUX auxiliary contact for?
AUX is needed for a scheme where the boiler or pump must start only after the valve has opened. Without AUX, the boiler may begin heating the heat carrier before the valve has opened — the water will «stagnate» in the boiler. AUX eliminates this situation: the boiler receives permission to start only when the valve confirms the open position.

How does the 412N differ from the 405N?
405N — 3-point: three states (open/stop/close), smooth control for mixing valves. 412N — two-position: two states (open/closed) + AUX. For zone valves where full opening or full closing is required — 412N. For smooth temperature mixing — 405N or 411.