The mechanical frost protection thermostat / frost monitor THERMASREG® FST with switching output, fully-active sensor rod, with automatic reset or with mechanical locking – with manual reset is available with capillaries in lengths of 0.6 m, 1.8 m, 3 m, 6 m, or 12 m. The frost protector is used for air and water-side temperature monitoring at heat exchangers water circulation systems, and heating registers against freezing up and to avoid frost damages, e.g. in ventilation and air conditioning ducts. All devices are self-secure with sensor breakage detection. In case of damage to the capillary-membrane system the relay automatically switches to heating function. THERMASREG® FST-3 and FST-3R can also be used for monitoring liquids. The sensor tube can be installed inside an immersion sleeve. Mounting clamps MK-05-K are included in the delivery (except FST-3 and FST-3-R).