Low speed interlock for a two stage two speed furnace
US5379752A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1993 |
| Grant date | Jan 10, 1995 |
| Priority date | — |
| Expiry date | Jul 12, 2013 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2237/10
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
A two-stage induced draft furnace is operated at either high heat or low heat with the gas valve switched to high-fire or low-fire. High-fire and low-fire combustion pressure switches sense the collector box flue gas pressure and actuate respective solenoids of the gas valve. Under some conditions the inducer can produce sufficient negative pressure at low fire to prove the high fire pressure switch and cycle the burners on high fire. To prevent this, relay contacts are interposed between the high fire pressure switch and the gas valve solenoid to deny thermostat power to the high-fire solenoid whenever there is a call for low heat.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.