Method for controlling an induced draft fan for use with gas furnaces
US5806440A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | May 20, 2016 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2233/10
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow. The motor speed and motor torque are also monitored to ensure that they are within selected limits indicative of safe operation and responsive to this input energization of a relay (KM1) is controlled to deenergize the gas valve and ignition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.