Robertshaw M601-25 1TKF9 Line Voltage Thermostat

The Robertshaw 801 M601-25, P/N 1TKF9, is a mercury-free line-voltage thermostat with an integrated thermometer for mechanical ambient temperature indication, designed to control electric baseboard and radiant heating systems. As a member of Robertshaw's 800 Series, it serves as a universal replacement that can retrofit many brands' line-voltage thermostats, simplifying upgrades in older electric-heat installations. It is a non-programmable SPST (single-pole) control intended for line-voltage heating duty, and its electrical ratings cover common US and international service: up to 25 A at 250 VAC, 18 A at 277 VAC, plus 1 HP at 125 VAC and 2 HP at 250 VAC, with a 125 VA pilot duty. This combination of ratings makes it suitable for a wide range of heating loads, from modest electric baseboard circuits to higher-demand radiant heating setups, while the built-in thermometer helps operators gauge current ambient conditions and anticipate the switch point. The device is designed to be installed in standard residential or light commercial circuits where a simple, durable mechanical control is preferred over programmable or electronic thermostats.