Thermostatic liquid-filled radiator valve head CALEFFI 204000 – liquid sensor, manual setpoint

CALEFFI 204000 thermostatic liquid-filled radiator valve head is a compact control element designed to regulate room temperature by sensing ambient conditions with a liquid-filled capsule. It replaces compatible manual thermostatic heads and provides straightforward temperature control for domestic and light commercial radiator systems. The device operates by expanding or contracting the internal liquid sensor, which drives the valve mechanism to modulate radiator flow and maintain the selected setpoint.

Advantages

The liquid sensor offers stable and precise response to room temperature variations, reducing oscillation and improving thermal comfort. Manual setpoint adjustment allows users to set a specific target temperature without relying on electrical power, which makes the head suitable for installations where simple, reliable mechanical control is preferred. Its compact design and compatibility with standard thermostatic valves facilitate straightforward replacement and retrofit in existing heating circuits.

Suitable for

• Replacement of compatible radiator thermostatic heads in residential heating systems
• Manual temperature control in apartments, houses and small commercial premises
• Retrofit projects for balancing and regulating radiator flow
• Hydronic heating systems where mechanical, non-electric control is required

Key specifications

• Control principle: liquid-filled temperature sensor reacting to ambient temperature
• Adjustment: manual setpoint control for room temperature
• Installation: direct mounting on compatible thermostatic valve bodies
• Operation: mechanical, no external power required
• Application: radiators in domestic and light commercial heating systems

How to use

To install, remove the existing thermostatic head from the valve body and place the CALEFFI liquid-filled head onto the valve spindle, securing it according to the valve manufacturer’s mounting instructions. Rotate the setpoint knob to the desired room temperature. The liquid sensor will expand or contract in response to ambient temperature, moving the internal mechanism to open or close the valve and regulate radiator flow. Periodically check mounting tightness and ensure the sensor capsule is exposed to room air rather than being blocked by curtains or furniture for accurate sensing.

Usage recommendations

Position the head where it can sense room temperature accurately—avoid direct sunlight, drafts or placement behind radiators. For consistent performance, use the head with valves and adapters recommended by the radiator or valve manufacturer and follow regular maintenance checks as part of the heating system service schedule.