Furnace control with safety circuit and non-volatile memory
US9500366B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 2013 |
| Grant date | Nov 22, 2016 |
| Priority date | — |
| Expiry date | Jul 23, 2035 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2231/20
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A furnace controller circuit includes a microprocessor with input ports and output ports including ports to issue control signals for actuation of inducer, gas burner, and furnace blower. A temperature-actuated limit switch commences a furnace shut-down sequence when the temperature of the furnace heat exchanger exceeds a predetermined limit temperature, and then resets to permit a turn-on sequence. An LED visible fault indicator is coupled to the microprocessor to provide visible fault messages. A non-volatile memory device coupled with the microprocessor is operative to store fault indications when present. In the event of power restoration after power failure, the limit switch status and other fault status are maintained. A lockout period is computed based on length of furnace run time until fault and recent fault history. Limit switch and other safety faults are recorded and these can be weighted and ranked based on age of each fault occurrence. The stored fault data can be used to identify erratic furnace operations, such as short cycling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.