| 摘要 |
A programmable electronic thermostat having selectable modes to control heating only, cooling only or both heating and cooling. This electronic thermostat enables an operator to program a series of desired temperatures over a repetitive heating or cooling cycle. The thermostat includes a clock that interrogates the stored program to generate a signal representative of the desired temperature for the present time which is compared with the measured temperature to generate control signals for a furnace or an air conditioner. The electronic thermostat may be placed in an automatic mode which controls both the furnace and the air conditioner. This automatic mode may be entered when a program of desired heating temperatures has been stored, whereupon the air conditioner is controlled based upon a cooling temperature having a predetermined relationship to the desired heating temperature. Similarly, this automatic mode may be invoked when only a program of desired cooling temperatures is stored. In such an event, the furnace is actuated based upon a heating temperature which has a predetermined relationship to the stored desired cooling temperature. In a further embodiment, both a program of desired heating temperatures and a program of desired cooling temperatures for the same time cycle may be stored, whereupon the electronic thermostat controls both the furnace and the air conditioner in accordance with the respective stored programs when in the automatic mode.
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