Method for detecting venting of a combustion appliance within an improper space

• US 6,250,133 B1
• Filed: 01/06/1998
• Issued: 06/26/2001
• Est. Priority Date: 01/06/1998
• Status: Expired due to Fees

• Current Assignee: Edwards Systems Technology, Inc.
• Original Assignee: Edwards Systems Technology, Inc.
• Inventors: Schell, Michael B.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Politzer, Jay L.
• Application Number:
  US09/004,142
• Time in Patent Office: 1,267 Days
• Field of Search: 73/232, 73/233.1, 250/343, 340/632, 126/116.A
• US Class Current: 73/23.31
• CPC Class Codes: G01N 1/2273 Atmospheric sampling
• CPC Class Codes: G01N 33/004 for CO, CO2
• CPC Class Codes: G01N 33/0063 using a threshold to release an alarm or displaying means alarm arrangements G08B, e.g. fire alarm actuated by the presence of smoke or gases G08B17/10, for other abnormal conditions G08B21/00
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A method for detecting improper venting of a combustion appliance within an interior space relies upon a carbon dioxide detector to determine whether a preselected criterion indicative of improper venting is exceeded. The preselected criterion can be a threshold concentration of carbon dioxide or a threshold level of rate of rise of carbon dioxide concentration that is exceeded at a specified time or over a specified interval of time. The method can be used to detect leaks in a residential furnace, at very low levels, during start up of the furnace by measuring the preselected criterion in a heated air duct.

Claims

1. A method for detecting venting of a combustion appliance within an improper space, comprising the steps of:

providing a combustion appliance;

operating the appliance in a manner to generate products of combustion, including carbon dioxide, and to generate heated air;

providing a space into which venting of the products of combustion is improper;

directing the products of combustion to a flue away from the improper space;

directing the heated air from said combustion appliance to a duct connecting to said improper space;

providing a carbon dioxide detector within the improper space;

establishing a preselected criterion for carbon dioxide within the improper space that is indicative of venting of products of combustion into the improper space;

operating the carbon dioxide detector in a manner to determine whether said preselected criterion for venting within the improper space is exceeded; and

generating an alarm signal in response to detecting that said preselected criterion for venting within the improper space is exceeded.

2. A method as recited in claim 1, wherein the preselected criterion is a threshold concentration of carbon dioxide.

3. A method as recited in claim 2, wherein the threshold concentration of carbon dioxide is approximately 4,000 ppm.

4. A method as recited in claim 1, wherein the preselected criterion is a threshold level of rate of rise of carbon dioxide concentration.

5. A method as recited in claim 4, wherein the threshold level of rate of rise of carbon dioxide concentration is approximately 25 ppm/minute while the combustion appliance is in operation.

6. A method as recited in claim 1, wherein the preselected criterion is a threshold level of rate of rise of carbon dioxide concentration which is exceeded over a preselected number of consecutive operational cycles of the combustion appliance.

7. A method as recited in claim 6, wherein the reduced threshold level of rate of rise of carbon dioxide concentration is approximately 25 ppm/minute while the combustion appliance is in operation.

8. A method as recited in claim 7, wherein the preselected number of consecutive operational cycles is 2 or more.

9. A method as recited in claim 1, wherein the duct includes a heated air duct that is connected to the combustion appliance by a fan.

10. A method as recited in claim 9, wherein the preselected criterion is measured in the heated air duct as close as practical to the heat exchanger.

11. A method as recited in claim 10, wherein the preselected criterion is measured when the combustion appliance is turned on to determine a warm up value of the preselected criterion before the fan begins blowing heated air through the heated air duct.

12. A method as recited in claim 11, wherein the preselected criterion is a rate of rise of carbon dioxide concentration.

13. A method as recited in claim 12, wherein the alarm signal is generated if the warm up value of the preselected criterion is greater than approximately zero ppm/minute.

14. A method as recited in claim 10, wherein the preselected criterion is measured when the combustion appliance is turned on and the fan has been blowing heated air through the heated air duct for greater than a preselected interval to determine an operational value of the preselected criterion.

15. A method as recited in claim 14, wherein the alarm signal is generated if the operational value of the preselected criterion is greater than approximately 5 ppm/minute.

16. A method as recited in claim 9, wherein the preselected criterion is measured in the immediate area outside of the heated air duct in the improper space.

17. A method for detecting improper venting of a combustion appliance within an interior space, comprising the steps of:

providing a combustion appliance;

operating the appliance in a manner to generate products of combustion, including carbon dioxide;

providing an interior space into which venting of the products of combustion is improper;

directing the products of combustion away from the interior space;

providing a carbon dioxide detector within the interior space;

operating the carbon dioxide detector in a manner to determine whether either of the following preselected criteria indicative of improper venting within the interior space is exceeded;

determining whether a threshold level of carbon dioxide is exceeded; and

either determining whether a threshold level of rate of rise of carbon dioxide concentration is exceeded or determining whether a threshold level of rate of rise of carbon dioxide concentration is exceeded over a preselected number of consecutive operational cycles of the combustion appliance; and

generating an alarm signal in response to detecting that any of said preselected criterion for venting within the interior space is exceeded.

18. A method as recited in claim 17, wherein the threshold level of carbon dioxide is approximately 4000 ppm, the threshold level of rate of rise of carbon dioxide concentration is approximately 25 ppm/minute while the combustion appliance is in operation and the number of consecutive operational cycles is 2 or more.

19. A method for detecting venting of a combustion appliance within an interior space, comprising the steps of:

providing a combustion appliance;

operating the appliance in a manner to generate products of combustion, including carbon dioxide, said combustion appliance heating air which is blown by a fan through a heated air duct that is disposed adjacent said combustion appliance;

directing the products of combustion to a flue away from the interior space;

providing a carbon dioxide detector within the heated air duct;

establishing a preselected criterion for carbon dioxide within the heated air duct that is indicative of venting of products of combustion into the interior space;

operating the carbon dioxide detector in the heated air duct in a manner to determine whether said preselected criterion for venting within the interior space is exceeded; and

generating an alarm signal in response to detecting that said preselected criterion for venting within the interior space is exceeded.