Vent overpressurization detection system for a fuel-fired, induced draft furnace
US4951651A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 28, 1989 |
| Grant date | Aug 28, 1990 |
| Priority date | — |
| Expiry date | Sep 28, 2009 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2233/02
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
In an inducted draft, fuel-fired furnace a flow restriction in the external exhaust flue is detected, and the furnace burners responsively deactivated, by a thermal sensing switch mounted in a spaced relationship with a small flow opening formed in a sensor housing externally secured to the inducer fan outlet section over a wall opening therein. During normal burner combustion product discharge flow through the exhaust flue, a small vane within the inducer fan outlet section creates a venturi therein which draws ambient air within the furnace housing across the temperature sensing switch and into the fan outlet section through the sensor housing opening. The temperature of this ambient air is below the switch set point so that continued burner operation is permitted. However, if the exhaust flue becomes restricted or blocked the resulting pressure increase within the inducer fan outlet section overcomes the venturi effect therein and forces hot burner combustion products outwardly through the sensor housing and across the temperature sensing switch. When the temperature of the switch reaches its set point, the switch operates to deactivate the furnace burners.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.