The Caleffi 203502 is a self-powered thermostatic control head with a remote contact probe. The probe straps to the pipe and senses medium temperature, so the head limits or controls the temperature of the circuit rather than the temperature of a room. Adjustable across 68 to 122 deg F (20 to 50 deg C).
Best for limiting supply temperature to a circuit, such as capping the feed to a radiant loop or a towel warmer.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
Self-Powered Room Temperature Control
A liquid-filled sensor expands and contracts with room temperature, closing the valve as the room reaches setpoint. No wiring, power supply or controller is required.
Contact Probe for Medium Temperature Limiting
The contact probe straps to the pipe and senses medium temperature rather than room air, so the head limits supply temperature to the circuit instead of controlling a room.
Fits Caleffi TRV Bodies
Threads onto Caleffi thermostatic radiator valve bodies, so heads and bodies can be selected independently.
Capillary Length
Supplied with a 2 m capillary, setting how far the sensor or adjuster can be mounted from the valve.
Technical Specifications
| Product Type | Thermostatic Control Head |
| Head Type | Contact Probe |
| Capillary length | 2 m |
| Medium temperature range | 68 to 122 deg F (20 to 50 deg C) |
| Series | Control Heads (Contact Probe) |
Documentation
Related Products
- Caleffi 200000 : Control Head, Built-in Sensor
- Caleffi 201000 : Control Head, Remote Sensor
- Caleffi 472000 : Control Head, Remote Knob
- Caleffi 449010 : Manual Knob
Frequently Asked Questions
What does Caleffi 203502 do?
It is a self-powered thermostatic control head with a remote contact probe. The probe straps to the pipe and senses the temperature of the medium, so the head controls or limits circuit temperature. It does not sense room air temperature.
Is Caleffi 203502 a room thermostat?
No. A standard control head senses room air and controls comfort. This version senses medium temperature at the pipe, and is used to cap or regulate the temperature delivered to a circuit.
What temperature range does Caleffi 203502 cover?
The medium temperature range is 68 to 122 deg F (20 to 50 deg C), set on a graduated dial. The probe is supplied on a 2 m capillary.
What is the warranty on Caleffi 203502?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Product Type:
- Thermostatic Control Head
- Product Family:
- Thermostatic control heads
- Series:
- Control Heads (Contact Probe)
- Head Type:
- Contact Probe
- Medium Temperature Range:
- 68 to 122 deg F (20 to 50 deg C)