Hot surface direct ignition system for gas furnaces
This patent describes a hot surface direct ignition system for gas furnaces and the like. It comprises: a high voltage circuit adapted to be connected to a source of high voltage AC current, the high voltage circuit including hot surface igniter means disposed in the path of incoming gas and being subjected to the heat of the gas flame when gas ignition is obtained whereby flame rectification is effected by the igniter means, a low voltage circuit adapted to be connected to a source of low voltage AC current. The low voltage circuit including thermostatic switch means controlling the energization of the low voltage circuit, an electrically operable gas valve, first rely means having contact means in the high voltage circuit controlling the energization of the igniter means, second relay means controlling the energization of the gas valve. The low voltage circuit including a field effect transistor means controlling the energization of the second rely means. The low voltage circuit also including first timing means controlling the energization of the first relay means, second timing means operatively interconnected to the field effect transistor means for controlling the energization of the second relay means, and third timing means operable upon the energization of the second relay means and the igniter means for a predetermined period of time, flame sensing means including a first capacitor connected always in parallel across the first relay contact means and always in series with the igniter means and being operatively interconnected to the field effect transistor means to be effective to maintain energization of the second relay means when gas ignition is obtained, the second relay means also having contact means in the low voltage circuit controlling the energization of the first, second and third timing means.
- Assignee:
- Robertshaw Control Co., Richmond, VA (USA)
- Patent Number(s):
- US 4997361; A
- Application Number:
- PPN: US 7-529997
- OSTI ID:
- 5382886
- Resource Relation:
- Patent File Date: 13 Jun 1990
- Country of Publication:
- United States
- Language:
- English
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