Thermal heads (TRV)

Thermal heads (TRV) replace a manual radiator knob with an electric actuator that opens or closes the valve in response to a thermostat signal.

Most actuators screw onto the standard M30x1.5 valve thread and are driven either by a simple 230 V on/off signal or by a 24 V PWM/0-10 V signal for finer modulation from a wired or KNX thermostat. The fail-safe position matters for comfort and protection: NC (normally closed) actuators shut the valve on power loss, while NO types stay open.

• Control signal — 230 V on/off is simplest to wire, 24 V PWM or 0-10 V from a room controller gives proportional, quieter modulation
• Fail-safe position — NC actuators close on power loss to prevent overheating, NO actuators stay open for frost protection
• Valve thread — confirm M30x1.5 compatibility with the existing radiator valve body before ordering