Every hydronic control loop inherits the accuracy of the probe that feeds it, which is why the 5123176010 is treated as a measurement instrument rather than an accessory. Catalogued by Schneider Electric inside the STP500 (10 kOhm, curve type 3) range, it carries a stainless-steel stem that is lowered into the water stream through a separate closed pocket, so the sensing element can be swapped during a maintenance window without draining the circuit.

Behind the stem a moulded, sealed transition separates wet metal from the cable, and the factory-fitted gland keeps condensation, dust and wash-down spray away from the conductor. Because the device is passive it draws no meaningful current, needs no firmware update and has no battery to schedule for replacement; the controller's own measuring circuit supplies the excitation and reads the returning value.

Every unit is checked against a traceable temperature reference before packing, and the paperwork that travels with it suits commissioning records, handover dossiers and energy-audit evidence.

Cooling mains and thermal stores reward depth. At 200 mm the element samples bulk water rather than the film clinging to the pipe wall, and on a large header that difference is the margin between a control loop that anticipates load and one that reacts to it late.

Curve type 3 gives a steeper resistance-to-temperature characteristic than the type 2 family, which translates into stronger resolution at the chilled end of the scale. That resolution lets the head end detect a fraction of a degree of drift and act before occupants notice, an advantage that compounds across a portfolio where hundreds of identical loops run in parallel and small errors aggregate into real energy cost.