| 摘要 |
The invention is a time variable set point thermostatic device adapted for use in a two-wire circuit of a heating or cooling system without additional wiring. Electric timer means interconnected with a thermostatic switch and starting relay means of a transformer having a primary and secondary winding periodically changes the set point of the thermostatic switch at selected intervals. The circuit is arranged to limit the current in the two-wire control circuit to a value less than that required to actuate the starting relay of the heating or cooling system in the two-wire control circuit with the thermostatic switch open and to actuate the starting relay when the thermostatic switch is closed when the ambient temperature to be regulated varies a determined amount from a selected temperature set point and the thermostatic switch is closed.
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