Abstract: A fully automatic system for providing electrical energy to heating and/or hot water systems in facilities serviced by single phase a.c. comprising a three-phase generator driven by single phase a.c. motor means intermittently operated on a load requirement basis wherein the three-phase generator output is normally maintained in an open-circuited condition. Upon controlled load demand, the motor means is energized and the three-phase output is connected to the load only upon achieving optimum operating speed, at which time switch means automatically connects the load to the three-phase output, which on-line condition is maintained until thermostatic control means senses the fact that the system has achieved the desired temperature level at which time the single phase motor means is deenergized.Additional sensing means are provided for protecting the system against damage due to excessive temperature and/or low level conditions.