Method and apparatus for preventing cold spot corrosion in induced-draft gas-fired furnaces
US6161535A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 1999 |
| Grant date | Dec 19, 2000 |
| Priority date | — |
| Expiry date | Sep 27, 2019 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF24H3/105
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for increasing the circulating airflow of induced-draft, gas-fired multi-stage furnaces without creating conditions that result in cold spot corrosion therein. Control circuitry is provided to selectably increase the circulating airflow of the furnace during low stage operation. The control circuitry is arranged so that increases in the magnitude of the circulating airflow of the furnace are accompanied by predetermined increases in the magnitude of the combustion airflow of the furnace. The magnitudes of the circulating and combustion airflows are so related to one another that the temperature at the output of the heat exchanger is maintained at a value which is approximately constant, and which is high enough to assure that water cannot condense thereon. The control circuitry may include a relay or relay-like device that is connected to prevent the high stage solenoid of the gas valve from becoming actuated during low stage operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.