Solid state emergency heat circuit
US4896828A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 23, 1989 |
| Grant date | Jan 30, 1990 |
| Priority date | — |
| Expiry date | Jun 23, 2009 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23N2231/10
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
An emergency heat circuit for a microprocessor-controlled furnace has a first emergency heat switch with one terminal in contact with a rectifier circuit that provides a DC voltage when the thermostat calls for heat, and another terminal connected to an emergency heat-active input of the microprocessor. A first opto-isolator has an optical actuator, such as an LED connected to the microprocessor failure output and a switched element unless such as a photo-transistor, with terminals connected in parallel to the first emergency heat switch. A second opto-isolator is also connected to the emergency heat switch and has an AC photo-actuated switch element, such as a photo-triac, connected, for example, to the W conductor and with an output connected to the rectifier circuit. The photo-triac latches on until the thermostat is satisfied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.