Johnstone L36-847 Cam-Stat. This Cam-Stat replaces all F47TS series controls. This stat i built with special fan controls and a built-in "heat-assist" timer. This Johnstone L36-847 Cam-Stat also includes a delayed blower as a function of time and/or temperature after the room thermostat calls for heat. With just a 25â€“60 second time delay, this Cam-Stat is efficient and effective.