Carbon monoxide sensor system

A safety system for a heating apparatus includes an inlet for receiving input gases for combustion and a flue for expelling flue gases. A carbon monoxide sensor is also included for monitoring carbon monoxide content in the heating apparatus. The safety system also includes a pressure switch which permits the input gases to mix with the flue gases based on the information from the carbon monoxide sensor.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to a carbon monoxide (CO) sensor and, more particularly, to CO sensor applications in heating systems.

Description of Related Art

Carbon monoxide (CO) forms after incomplete or partial combustion of a hydrocarbon. CO poisonous gas is the result when combustion occurs without a sufficient amount of oxygen present to react with the hydrocarbon. Heating systems that generate heat by combustion may include one or more sensors to detect a gas concentration of carbon monoxide. A controller communicates with the sensors to monitor the gas concentration to deactivate the heating system if and when deactivation is needed based on high CO content.

Current CO sensors detect gas concentration of a flue gas, therefore the sensor applications are often applied directly in a flue of a heating system. Such a location in a heating system is where ambient conditions for the sensor are extreme, therefore leading to a short sensor life.

Additionally, current systems include a pressure switch application which includes a safeguard switch that selectively permits air to enter a heating system to mix with a portion of flue gas. However, the switch application does not ensure that the air delivered for combustion is adequate for clean combustion.

Therefore, there is a continuing need for improved CO sensors that can help provide clean combustion in heating systems, while also prolonging sensor life to increase efficiency and lessen cost.

SUMMARY OF THE INVENTION

The general object of the invention can be attained, at least in part, through the application of a carbon monoxide (CO) sensor as part of a safety system for shutting off burner operation in a heating system. The safety system for a heating apparatus includes an inlet for receiving input gases for combustion, a flue for expelling flue gases, a CO sensor for monitoring CO content in the heating apparatus, and a pressure switch for permitting the input gases to mix with the flue gases.

The CO sensor is preferably positioned within a bypass circuit of the heating apparatus. The CO sensor can continuously monitor an amount of flue gas recirculation. The CO sensor can also communicate with the pressure switch to open or close a valve between the inlet and the flue. The CO sensor may be positioned within a recess between the inlet and the bypass circuit. The safety system may also include a blower for expelling flue gases out of the flue.

The general object of the invention can also be attained through a safety system for a heating apparatus with an inlet for receiving input gases for combustion and a flue for expelling flue gases. A bypass circuit is preferably positioned between the inlet and the flue. A CO sensor is also included for monitoring CO content in the heating apparatus. The CO sensor may be positioned within the bypass circuit.

The safety system may also include a pressure switch adapted to permit the input gases to mix with the flue gases. The pressure switch can also open and close the bypass circuit. The bypass circuit may include a valve between the inlet and the flue.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a CO sensor application for furnaces, boilers and water heaters. The invention identifies when a burner is operating unsafely. The invention also increases the life of CO sensors.

An operation of the invention includes shutting off burner operation for the conditions of a blocked flue, a blocked inlet and recirculation. The invention provides improved flue gas recirculation. The heating system of the invention captures recirculation within a combustion system and extends CO sensor life and reliability.

A CO sensor monitors the amount of flue gas recirculation in the heating system, ensuring that delivered air is adequate for clean combustion. The invention can identify when a vent or air inlet blockage or vent gas recirculation is occurring where the blockage is prohibiting clean combustion of a product.

The CO sensor is connected to the heating system by a bypass circuit where the CO sensor monitors the combustion performance of the unit. Here, the CO sensor sustains a longer life as the CO sensor is put in a benign environment in comparison to the overall combustion process.

The FIGURE shows a heating system100with a CO sensor102as part of a safety system according to one preferred embodiment of this invention. The heating system100includes a gas inlet104for incoming combustion gases and a flue106for exiting flue gases. The CO sensor102is preferably located inside the heating system100downstream from the gas inlet104. The CO sensor102may be positioned inside a recess116as part of the components of the heating system100. Downstream from the CO sensor102, the heating system100additionally includes a pressure switch108for monitoring and shutting off burner operation in the system.

The pressure switch108is included as part of a bypass circuit110of the heating system100. The bypass circuit110is arranged between the inlet104and the flue106. The bypass circuit110is downstream of the CO sensor102, thereby effectively separating the CO sensor from flue gases depending on whether the bypass circuit112is activated by the pressure switch108. The bypass circuit100further separates the CO sensor102from flue gases with the aid of a valve114. The valve114is part of the bypass circuit110and can be opened or closed as needed.

Gaseous products circulate throughout the heating system100with a blower112. The blower112may be any conventional or commonly used blower/blower system used in heating systems. Products generated by the heating system can exit the heating system through the flue106and/or enter the bypass circuit110and contact the pressure switch108before reaching the CO sensor102.

Using the CO sensor102and the pressure switch108, the invention can shut off burner operation in the system100for the conditions of a blocked flue, Burner operation can also be shut off for a blocked inlet104and for recirculation. The CO sensor102and corresponding pressure switch108monitor the amount of flue gas recirculation through the heating system100, ensuring that air delivered is adequate for clean combustion.

For example, a mixture of approximately 20-30% (preferably 22%) O2and 70-80% (preferably 78%) N2enter the heating system100through the gas inlet104. However, it is to be understood that other mixtures in additional proportions may also enter the gas inlet. When flue gases exit the heating system100after combustion, through the flue106, the flue gases approximately include 5-15% (preferably 9%) CO2and around 400 ppm of CO (along with some O2and N2as well). The specifics of the preferred gas content can be detected with the CO sensor102, and also monitored with the pressure switch108using the bypass circuit110.

In some embodiments of the invention, the pressure switch can also be a sensor. Other embodiments may include additional modification to the CO sensor to adjust sensor response and signal delay. Such modifications may include greater detection sensitivity in a feedback signal of the CO sensor, for example, adjusting between 100 ppm of CO and 400 ppm. A higher control signal may also be adjusted in terms of flue gas flow in the heating system. The control signal may include adjustments to a diameter for flue gas to flow through the heating system, or adjusting lengths of vent and/or air systems of the heating system.

Because the CO sensor102is connected by the bypass circuit110, the CO sensor102also monitors the overall combustion performance of the heating system100. Also due to placement in or near the bypass circuit110, the overall lifespan of the CO sensor102is increased since the sensor102is not placed in the path of combustion gases directed out of the flue106.