Furnace draft control system with electronic loss-of-draft timer
US4374569A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 29, 1981 |
| Grant date | Feb 22, 1983 |
| Priority date | — |
| Expiry date | Jul 29, 2001 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2235/10
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
The system includes a damper plate equipped with a draft controller or sensing switch and a motor for positioning the damper plate to control the furnace draft. Upon generation of a call-for-heat signal, an initialization signal drives the damper off its closed position. From then on, draft must be sensed by the draft controller switch to complete the cycle to open the damper plate. When the damper plate is fully opened, a fuel and ignition control circuit is energized to supply fuel to the furnace, and an electronic timer is energized to generate a signal which establishes a trial-for-draft period. When the fuel is ignited, the draft will increase and energize the motor to move the damper plate off the fully open position during the trial-for-draft period, and thereafter, the position of the damper plate is controlled by the draft controller switch to achieve a proper draft within design range. If draft is lost at any time, the controller moves the damper to the full open position and a loss-of-draft safety timing period commences. If draft is not re-established during this period, the system shuts off the fuel and locks out. When the call for heat is satisfied, the system closes …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.