COMBUSTION AIR VENT CONTROL FOR FURNACES

Abstract

Various apparatus are disclosed for controlling the combustion air vent of fuel-fired furnaces. For a first embodiment of the invention, a furnace-controlled air valve is placed in the combustion air duct. When the furnace begins a heating cycle, the valve is opened. When the heating cycle ends, the valve is closed and remains closed until the beginning of the next heating cycle. For a second embodiment of the invention, a positive-displacement air pump is placed in the combustion air duct. The air pump pumps air from the exterior into the mechanical room at a controlled rate during each heating cycle of the furnace. The air valve or the air pump is controlled directly or indirectly by the furnace thermostat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway view of a home in which a combustion furnace has been installed in the mechanical room;

FIG. 2 is an elevational view of a combustion air vent having a flapper valve installed therein, with the valve operated by a solenoid;

FIG. 3 is an elevational view of a combustion air vent having a butterfly valve installed therein, with the valve operated by a solenoid;

FIG. 4 is an elevational view of a combustion air vent having a ball valve installed therein, with the valve operated by a solenoid and in its open position;

FIG. 5 is an elevational view of a combustion air vent having a ball valve installed therein, with the valve operated by a solenoid and in its closed position;

FIG. 6 is an elevational view of a combustion air vent having a ball valve installed therein, with the valve operated by an electric motor;

FIG. 7 is an elevational view of a combustion air vent having a balloon valve installed therein, with the valve controlled by an electric pump and a solenoid-actuated pressure-release valve;

FIG. 8 is a cross-sectional view through a flexible vane pump;

FIG. 9 is a cross-sectional view through a sliding vane pump;

FIG. 10 is a cross-sectional view through a lobe pump;

FIG. 11 is a cross-sectional view through an internal gear, or gerotor, pump;

FIG. 12 is a cross-sectional view through an external gear, or Roots-type, pump;

FIG. 13 is an electrical block diagram of the control circuit for the control valve of FIGS. 2, 34 or 6;

FIG. 14 is an electrical block diagram of the control circuit for the forced air pump of either FIGS. 8, 9, 10, 11 or 12; and

FIG. 15 is an electrical block diagram of a control circuit for the balloon control valve of FIG. 700.

Claims

1. In combination with a fuel-burning furnace controlled by a thermostat, said furnace being installed in an enclosure located within a habitable structure and requiring a duct for admitting combustion air from outside the structure into the enclosure, a duct control device comprising: an apparatus having a first state which blocks the flow of combustion air through the duct and a second state which allows the flow of combustion air through the duct; anda control apparatus which establishes and maintains said first state during periods between furnace heating cycles and establishes and maintains said second state during furnace heating cycles.

2. The combination of claim 1, wherein said apparatus is a valve having a movable control element which either closes the duct when in a first position corresponding to said first state or opens the duct when in a second position corresponding to said second state, said movable control element operating under the control of said thermostat.

3. The combination of claim 2, wherein said valve is selected from the group consisting of balloon valves, flapper valves, ball valves, and butterfly valves.

4. The combination of claim 2, wherein said movable control element is moved between said first and second positions by mechanical actuators selected from the group consisting of an electromagnet in combination with a spring, an electromagnet in combination with gravitational force, DC electric motors and AC electric motors.

5. The combination of claim 1, wherein said apparatus is a positive-displacement pump which prevents combustion air from flowing through the duct when in said first state and pumps combustion air through the duct when in said second state.

6. The combination of claim 5, wherein said positive-displacement pump is selected from the group consisting of sliding vane pumps, flexible vane pumps, external gear pumps, internal gear pumps, Roots-type pumps, and rotary lobe pumps.

7. The combination of claim 5, wherein said positive-displacement pump is powered by electrical current that is controlled by a switch that, in turn, is controlled by said thermostat.

8. The combination of claim 7, which further comprises a transistor to which is applied a control voltage corresponding to an output voltage from said furnace thermostat, and wherein a high level control voltage causes said transistor to transmit power to said switch, thereby turning it ON, and a low level control voltage causes said transistor to cut power to said switch, thereby turning it OFF.

9. The combination of claim 5, wherein said positive-displacement pump is powered by an electric motor selected from the group consisting of DC and AC motors.

10. In combination with a fuel burning heating device controlled by a thermostat, said heating device installed in an enclosure located within a habitable structure and requiring a duct for admitting combustion air from outside the structure into the enclosure, a duct control apparatus comprising: means for blocking the flow of combustion air through said duct during periods between furnace heating cycles; andmeans for allowing the flow of combustion air through said duct during furnace heating cycles.

11. The combination of claim 10, wherein said means for blocking and said means for allowing is a valve having a movable control element which either closes the duct when in a first position or opens the duct when in a second position, said movable control element operating under the control of said thermostat.

12. The combination of claim 11, wherein said valve is selected from the group consisting of balloon valves, flapper valves, ball valves, and butterfly valves.

13. The combination of claim 11, wherein said movable control element is moved between said first and second positions by the combination of an electromagnet and a spring.

14. The combination of claim 11, wherein said movable control element is moved between said first and second positions by the combination of an electromagnet and gravity.

15. The combination of claim 11, wherein said movable control element is moved between said first and second positions by an electric motor selected from the group consisting of DC motors and AC motors.

16. The combination of claim 10, wherein said means for blocking and said means for allowing is a positive-displacement pump which operates under the control of said thermostat.

17. The combination of claim 13, wherein said positive-displacement pump is selected from the group consisting of vane pumps, flexible member pumps, external gear pumps, internal gear pumps, Roots-type pumps, and rotary lobe pumps.

18. The combination of claim 13, wherein said positive-displacement pump is powered by an electric motor selected from the group consisting of DC and AC motors.

19. The combination of claim 10, wherein said means for blocking and said means for allowing are directly controlled by electrical power passing through a switch that is controlled by a signal generated by said thermostat.

20. The combination of claim 10, wherein said switch is selected from the group consisting of solenoids, bipolar junction transistors, junction field-effect transistors, and insulated-gate field effect transistors.