The E815/F accurately controls heating or air conditioning within a selectable temperature range between -2°C to and 12°C in conjunction with an adjustable hysteresis (differential) of anything between 0.25°C and 5°C.

Frost (/F)
This thermostat offers a much lower thermostatic control range of -2°C to +12°C. The unit operates as normal but has a lower temperature setpoint, primarily used for frost protection.