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:
Dec. 16, 1980
Filed:
Nov. 13, 1978
Thomas E Hayes, Goshen, IN (US);
Johnson Controls, Inc., Milwaukee, WI (US);
Abstract
A furnace ignition and draft control system includes a damper plate movable under control between a closed and an open position. When a call for heat signal is generated, a holding relay is actuated to energize a damper motor to open the damper provided the damper plate was closed when the signal was generated, otherwise the system will not operate. After the damper is run to the full open position and this is proved, a fuel control circuit is actuated to supply fuel to the furnace, and a trial-for-draft period is initiated. A draft controller energizes the damper motor to open the damper if draft is less than a first predetermined value and to close the damper if draft is greater than a second predetermined value. The predetermined draft values define a desired draft range in which the damper is not operated. If a draft greater than the second value is sensed within the trial period, the draft controller partially closes the damper to control the draft value within the desired draft range, otherwise the system locks out at the end of the trial period. If draft is lost at any time, the controller moves the damper to the open position and a loss-of-draft safety timing period commences. If draft is not reestablished during this period, the system shuts off the fuel and locks out. If the call for heat is satisfied, the system closes the damper and is prepared for another operating cycle, having tested the operativeness of all major components without failure. Any failure would have locked the system out.