As a quartz-driven timer

Built to handle the rigorous demands of commercial and industrial boilers

meaning it does not require a common 'C' wire for operation

Tamper-Resistant Design: Includes a protective cap to secure temperature settings after final commissioning

The "VL" designation confirms an integral vent limiting orifice

Siemens Building Technology QFM2160U Sensor 322838-754 As a quartz-driven timerThe Siemens Building Technology QFM2160U Sensor is a high performance Duct RH Sensor designed for critical HVACR applications where long term stability and precision are paramount. This Siemens Q Series sensor monitors relative humidity and temperature in air ducts, providing dual 0 10Vdc output signals for seamless integration with building automation systems. Built for the rigors of industrial environments, the QFM2160U features a capacitive sensing