HERZ MINI underfloor heating return temperature limiter set 1/2", angle, 25–60 °C, 1920124

HERZ 1920124 is an angle-pattern return-temperature limiter set designed for automatic temperature control of a small hydronic underfloor-heating circuit. It combines a HERZ MINI return-temperature limiter with a HERZ TS-90 angle thermostatic valve and provides self-acting control without an electrical actuator or external electronic controller.

The set consists of the HERZ MINI return-temperature limiter 1 9201 00 and HERZ TS-90 angle thermostatic valve 1 7724 37. The valve is DN15 / 1/2". It features a cone-sealed connection and a G 3/4 male pipe connection with cone for suitable HERZ compression adapters.

The return-temperature limiter operates as a self-acting proportional controller. The temperature of the returning heating medium is transferred through the valve body to the temperature sensor. If the return temperature exceeds the selected setting, the valve progressively closes and reduces the flow through the underfloor-heating circuit. When the temperature decreases, the valve opens again.

The adjustment range is 25–60 °C. The selected setting range can be mechanically limited or locked using HERZ limiting pins 1 9551 02, which must be ordered separately. The limiter connection is M28 × 1.5.

The HERZ MINI limiter is not a conventional room-temperature thermostatic head. It regulates the return temperature of the heating medium, rather than directly sensing room-air temperature.

The HERZ TS-90 angle valve 1 7724 37 has a Kvs value of 1.1 m³/h and does not feature integrated pre-setting. The TS-90 valve itself is rated for a maximum operating pressure of 10 bar and a technical maximum operating temperature of 120 °C.

For the RTB underfloor-heating application, HERZ specifies a maximum heating supply temperature of 70 °C, maximum differential pressure of 0.2 bar and a recommended maximum limiter setting of 55 °C. The recommended maximum operating temperature for underfloor heating is approximately 35 °C.

The system is intended for relatively small individual underfloor-heating circuits. HERZ specifies an approximate maximum heating load of 1000 W and a maximum floor-heating pipe length of around 20 m. Actual system limits depend on pipe size, pipe spacing, floor construction, operating temperatures and room heat demand.

The angle configuration is particularly suitable where pipework approaches the valve at a right angle. G 3/4 compression adapters for copper, steel or plastic pipes are selected according to the pipe dimensions and ordered separately.

Technical information