摘要 |
A controller for a two-stage heat source is provide, which may be connected to either a single stage or a two-stage thermostat to provide low stage heating for a variable time period before switching to high stage heating. The controller includes at least a first terminal for receiving a signal requesting heating from a single-stage thermostat or a two-stage thermostat connected to the first terminal. A microcontroller in communication with the first terminal determines a duty cycle value for a heating cycle based on the duration in which a signal at the first terminal is present relative to the duration of the heating cycle. The microcontroller determines a low stage time limit from the duty cycle, and provides low stage heating when a signal is present at the first terminal for a time period not more than the time limit, and switches to high stage heating after the time limit.
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