The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 05, 1985
Filed:
Aug. 31, 1983
Dale A Mueller, New Hope, MN (US);
Honeywell Inc., Minneapolis, MN (US);
Abstract
A furnace control apparatus for a downflow forced warm air furnace uses a microprocessor and thermostat to initiate and control the start-up of the furnace. During the initial start-up operation, the microprocessor receives an input signal from the thermostat indicative of the need for a furnace operation and produces an output signal for controlling, in combination with the thermostat which responds to the temperature of the space to be heated, an actuation of a gas valve to supply gas to the furnace. Subsequently, an analog temperature sensor in an air supply duct is used to supply another input signal through an analog-to-digital converter to the microprocessor representative of the air temperature in the duct. The microprocessor stores the value of the air temperature following the start-up of the burner and subsequently turns on an air circulator. Following the energization of the air circulator, the microprocessor determines via a fixed logic sequence whether the delivered air temperature rises a minimum amount above the stored initial temperature after a preset time period as an indication of a circulator failure. Additionally, the analog temperature sensor is used by the microprocessor to determine if the delivered air temperature ultimately rises above a predetermined high or maximum limit an an indication of a restriction in an air return duct. In either case of the delivered air temperature not meeting aforesaid criteria, the microprocessor deactuates the gas valve to interrupt the flow of gas to the burner to protect the heating system.