The PT series mechanical thermostat timers allow heating or cooling control according to our own lifestyle requirements. The PT series thermostat timers have been designed to work with all energy sources (gas, heating oil, electricity). Mechanical thermostat timer featuring timer switch with lock-in time band pointers. Daily programming without (PT10/11) or with backup power (PT20/21). Temperature control from +5° to +30°C using saturated steam expansion thermostat. Night-time lowering of the temperature by 3°C in models PT11/ 21. Switch for selecting operating mode (TIMED AUTOMATIC / OFF / THERMOSTAT). Mains powered. Switching contacts (SPDT).