COMBUSTION BLOWER CONTROL FOR MODULATING FURNACE

• US 20080213710A1
• Filed: 05/19/2008
• Published: 09/04/2008
• Est. Priority Date: 10/18/2006
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Schultz, Michael W.
• Granted Patent: US 8,591,221 B2
• Time in Patent Office: Days
• US Class Current: 431/12
• CPC Class Codes: F23N 1/027 using mechanical means
• CPC Class Codes: F23N 2233/04 with variable speed
• CPC Class Codes: F23N 2241/02 Space-heating
• CPC Class Codes: Y10T 137/2496 Self-proportioning or correlating systems

Abstract

A forced air furnace may include a pneumatically modulated gas valve that is configured to provide gas to a burner. A pneumatic sampling device may be disposed proximate a combustion blower and may be configured to provide the pneumatically modulated gas valve with a first pneumatic signal and a second pneumatic signal that are representative of fluid flow through the pneumatic sampling device. The pneumatically modulated gas valve may regulate gas flow in accordance with the first and second pneumatic signals. In some cases, the pneumatic sampling device may include a restriction, a first pressure port disposed upstream of the restriction and a second pressure port disposed downstream of the restriction. The first and second pressure ports may provide the first and second pneumatic signals to the pneumatically modulated gas valve.

Claims

1. A forced air furnace comprising:

a burner;

a pneumatically modulated gas valve configured to provide gas to the burner;

a combustion blower in fluid communication with the burner; and

a pneumatic sampling device disposed proximate the combustion blower, the pneumatic sampling device configured to provide the pneumatically modulated gas valve with a first pneumatic signal and a second pneumatic signal, the first and second pneumatic signals representative of fluid flow through the pneumatic sampling device, the pneumatically modulated gas valve regulating gas flow in accordance with the first and second pneumatic signals.

2. The forced air furnace of claim 1, wherein the pneumatic sampling device is disposed upstream of the combustion blower.

3. The forced air furnace of claim 1, further comprising a collector box, the collector box is disposed in fluid communication between the burner and the combustion blower.

4. The forced air furnace of claim 3, wherein the pneumatic sampling device is disposed in fluid communication between the collector box and the combustion blower.

5. The forced air furnace of claim 4, wherein the pneumatic sampling device is in contact with an exterior of the collector box and an exterior of the combustion blower.

6. The forced air furnace of claim 3, wherein a combustion gas flow path extends from the collector box to the combustion blower, and the pneumatic sampling device is configured to form a portion of the combustion gas flow path from the collector box to the combustion blower.

7. The forced air furnace of claim 3, wherein the pneumatic sampling device comprises an annular housing and a restriction disposed within the annular housing.

8. The forced air furnace of claim 7, wherein the pneumatic sampling device further comprises a first pneumatic sampling port that provides the first pneumatic signal and a second pneumatic sampling port that provides the second pneumatic signal, the first and second pneumatic sampling ports being arranged to sample a pressure change across the restriction.

9. The forced air furnace of claim 8, wherein one of the first and second pneumatic sampling ports is disposed upstream of the restriction and another of the first and second pneumatic sampling ports is disposed downstream of the restriction.

10. A combustion appliance comprising:

a burner;

a pneumatically modulated gas valve configured to provide gas to the burner;

a combustion blower having a combustion blower inlet;

a restriction disposed in fluid communication with the combustion blower;

a first pressure port disposed upstream of the restriction; and

a second pressure port disposed downstream of the restriction;

wherein the first pressure port and the second pressure port are in fluid communication with the pneumatically modulated gas valve.

11. The combustion appliance of claim 10, wherein the restriction is upstream of the combustion blower.

12. The combustion appliance of claim 11, further comprising a collector box positioned upstream of the combustion blower, the restriction disposed between the collector box and the combustion blower.

13. The combustion appliance of claim 10, wherein the restriction comprises a plate and an orifice disposed within the plate, the plate disposed perpendicular or substantially perpendicular to fluid flow.

14. The combustion appliance of claim 13, wherein the first pressure port is proximate the plate but disposed upstream of the plate.

15. The combustion appliance of claim 13, wherein the second pressure port is proximate the plate but disposed downstream of the plate.

16. The combustion appliance of claim 13, wherein the restriction comprises a hollow structure with the plate disposed within the hollow structure.

17. The combustion appliance of claim 16, wherein the hollow structure includes a shape that is complementary to a shape of the combustion blower inlet.

18. The combustion appliance of claim 10, wherein the restriction is molded into the combustion blower inlet.

19. A method of operating a modulating combustion appliance having a pneumatically modulated gas valve, a burner, a combustion blower and a collector box, the method comprising the steps of:

obtaining a first pneumatic signal from a first location downstream of the collector box;

obtaining a second pneumatic signal from a second location downstream of the first location; and

controlling the pneumatically modulated gas valve in accordance with the first pneumatic signal and the second pneumatic signal in order to modulate gas flow to the burner.

20. The method of claim 19, wherein the first location and the second location are upstream of the combustion blower.

21. The method of claim 19, wherein the combustion appliance further comprises a restriction disposed between the collector box and the combustion blower, and the first location is upstream of the restriction while the second location is downstream of the restriction.

22. A pneumatic sampling device for sampling a flow rate of a combustion gas flow within a furnace, and for producing a first pressure signal and a second pressure signal that can be used by a pneumatically modulated gas valve to modulate the gas provided to a burner of the furnace, the pneumatic sampling device comprising:

a housing having an upstream end and a downstream end, and walls that define a lumen that extends from the upstream end to the downstream end, the lumen for passing a combustion gas flow therethrough;

a plate extending inwardly from the walls of the housing, the plate positioned intermediate between the upstream end and the downstream end of the housing and defining an opening that is smaller in cross-section that the lumen;

a first port situated upstream of the plate but downstream of the upstream end of the housing, the first port extending through the wall of the housing and establishing fluid communication with the lumen, the first port providing the first pressure signal; and

a second port situated downstream of the plate but upstream of the downstream end of the housing, the second port extending through the wall of the housing and establishing fluid communication with the lumen, the second port providing the second pressure signal.

23. The pneumatic sampling device of claim 22 wherein the housing is configured to be mounted to an inlet of a combustion blower of a furnace.

24. The pneumatic sampling device of claim 22 wherein the housing has an outer generally cylindrical shape.