Thermostatic return temperature protection valve CALEFFI DN32 (1 1/4") adjustable 55°C

Thermostatic return temperature protection valve CALEFFI DN32 (1 1/4") adjustable 55°C is designed to maintain a minimum return-water temperature in closed hydronic heating systems. The valve monitors return flow and mixes hotter supply water to keep the return temperature at the selected setpoint, preventing boiler condensation and helping maintain efficient combustion. This model fits DN32 piping and features an adjustable thermostat element factory-set to 55°C for straightforward commissioning and stable operation in radiator circuits, boilers and auxiliary heating loops.

Advantages

The thermostatic return temperature protection valve provides stable temperature control without external power, using a self-actuating sensing element. It reduces the risk of corrosion and condensation in condensing and non-condensing boilers by ensuring return-water temperature does not fall below the selected threshold. The compact DN32 body and robust internal components support long service life and low maintenance. An adjustable setpoint allows installers to adapt the valve to system requirements during commissioning.

Suitable for

• Hydronic heating systems where minimum return temperature must be maintained
• Radiator circuits and distribution manifolds
• Boiler protection to prevent flue gas condensation
• Integration into secondary loops and buffer tank circuits

Key specifications

• Connection size: DN32 (1 1/4") compatible with standard threaded fittings
• Function: thermostatic mixing for return temperature protection
• Adjustable setpoint: factory related to 55°C (adjustable around this value)
• Operating principle: self-acting thermostatic element, no external power required
• Typical application temperature range: heating system temperatures up to standard boiler operating levels
• Material and construction: corrosion-resistant valve body and internal moving parts designed for heating circuits

How to use

Install the valve in the return line close to the boiler or heat source following hydraulic flow direction markings. During commissioning, set the thermostat to the desired minimum return temperature, using the factory setpoint of 55°C as a reference. Ensure system water quality and filtration are appropriate to avoid debris entering the valve. The valve operates automatically: when return water is below the setpoint it mixes warmer supply water into the return flow; once the return reaches the set temperature the mixing closes and normal flow resumes.

Usage recommendations

Position the valve where it is accessible for adjustment and maintenance, and combine it with appropriate strainers and air separators in the circuit. Verify compatibility with system pressures and temperatures, and follow manufacturer guidelines for commissioning to maintain boiler warranty conditions and achieve reliable return temperature protection.