| 摘要 |
PURPOSE: To provide a simple economical electronic control system, by energizing an induced draft blower which supplies combustion air and, at the same time, operating an air circulating fan at a low speed when space heating is made or at a high speed when a hot air furnace is in an overheated state. CONSTITUTION: When a normally open thermostat 27 for heating is closed and a normally closed overheat switch 25 is closed as it is, an electric current flows to an air flow switch 31 and actuates an induced draft blower 21. A delayed turning-on signal is generated from a timer circuit 39 and a control relay 211 for heating is energized. As a result, a supply fan blower 13 is operated at a low speed. When the temperature of a furnace exceeds a prescribed safety limit, the normally closed overheat switch 25 is opened and a transistor which is usually maintained in a turned-off state is turned on. Then an electric current turns on the high-speed operation of a supply fan by energizing a control relay 209, and further actuates the induced draft blower 21 by energizing a control relay 219.
|
