Method and apparatus for controlling furnace
US4189296A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 13, 1978 |
| Grant date | Feb 19, 1980 |
| Priority date | — |
| Expiry date | Mar 13, 1998 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2235/10
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A control system for use with gas-fired appliance installations, such as a furnace, includes a switch responsive to normal draft levels in the vent stack. At the start of a heating cycle, and in the absence of draft, the switch permits a pre-draft enabling circuit to tentatively enable the furnace controller for a predetermined time. The controller opens a stack damper plate and actuates the ignition system and gas valves of the furnace. If draft is not established within the predetermined time, the pre-draft enabling circuit times out and the gas is shut off. If normal draft is sensed within the predetermined time, the draft responsive switch permits the furnace controller to be operated as long as the thermostat calls for heat. If, for any reason, draft subsequently stops, the control system re-cycles itself; and if draft is not re-established before the pre-draft enabling circuit times out, the system deactivates the furnace controller. The control system also includes a normally closed barometric damper, which is mounted in the vent stack and is responsive to both excessive positive pressure and to excessive draft (sub-ambient pressure) to open, and thereby neutralize the exces…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.