13b and 13c a control transformer 14 and a programmable thermostat 18 the control transformer 14 in the preferred embodiment supplies 24 volts of power it is normally part of the control system for the furnace 12 the control transformer 14 provides power to the thermostat 18 the programmable thermostat 18 is conductively coupled to each of the three relays 13 and to the control transformer 14 the three relays are also each conductively coupled to the transformer 14 relay 13a is conductively coupled to the air conditioning unit 12a and operates to turn it on relay 13b is conductively coupled to the furnace 12b and operates to turn it on relay 13c is conductively coupled to the furnace 12c and operates to turn it on the thermostat 18 includes a selector switch 15 a switching relay 16 a microprocessor controller 17 and a monitor 20 in an alternate embodiment the monitor can be separate from but conductively coupled to the thermostat 18 in still another embodiment the monitor 20 can be part of the controller 17 integrated into the controller 17 by suitable software the switching relay 16 is conductively coupled to the control transformer 14 the selector switch 15 the controller 17 and the monitor 20 the monitor 20 is also conductively coupled to the controller 17 the monitor is programmed with desired positions of the relay those positions programmed by the user.