Patent Application
20110277706
The present invention relates to heating devices, and particularly, to gas heating devices. More particularly, the invention relates to a controller used for controlling gas heating devices.
An exemplary gas-fired heating device is a gas water heater having a burner. Gas water heaters often include a combustion chamber and an air plenum disposed below a tank, such as a water tank. A gas manifold tube, an ignition source, a thermocouple, and a pilot tube typically extend into the combustion chamber. When the temperature of the water in the tank falls below a set minimum, fuel is introduced into the combustion chamber through the gas manifold tube and a burner element. This fuel is ignited by a pilot burner flame or the ignition source, and the flame is maintained around the burner element. Air is drawn into the plenum via an air inlet, and mixes with the fuel to support combustion within the combustion chamber. The products of combustion typically flow through a flue or heat exchange tube in the water tank to heat the water by conduction.
In one embodiment, the invention provides a new gas water heater having a burner, a pilot, a gas valve coupled to the pilot, a thermopile thermally coupled to the pilot flame and operable to generate an output voltage, and a controller powered by the thermopile and coupled to the gas valve.
In a more specific embodiment, the controller is operable to control the gas valve based on the output voltage it receives from the thermopile. The controller includes a processor that processes a voltage value received by the controller and communicates a shutdown signal for preventing gas flow to the pilot and/or burner when an insufficient amount of voltage is outputted by the thermopile.
In another embodiment, the invention provides a controller for a gas water heater. The gas water heater includes a burner, a pilot, an igniter, an electrically controlled gas valve, and a thermopile. The thermopile can be positioned in a standing pilot flame provided by the pilot. The standing pilot flame causes the thermopile to generate an output voltage that it used to power the controller and the electrically controlled gas valve. The controller responds to an insufficient amount of output voltage provided by the thermopile by, for example, closing the electrically controlled gas valve. The insufficient amount of output voltage can indicate the presence of a possible flammable vapor event or a possible lint, dust, or oil blockage event. Once the electrically controlled gas valve receives the shutdown signal it closes and prevents gas flow to the pilot and burner.
In another embodiment, the invention provides a method of controlling a gas water heater. The gas water heater includes a burner, a pilot, an igniter, a thermopile, a controller, and a gas valve. The method can include detecting a possible flammable vapor event or a possible lint, dust, or oil blockage event. The thermopile produces an output voltage in response to a standing pilot flame generated by the pilot and igniter. The output voltage generated by the standing pilot flame can be between about 400 and 800 millivolts. When the thermopile outputs an insufficient amount of voltage, a voltage less than 400 millivolts, for example, the controller generates a shutdown signal and closes the gas valve. Alternatively, when the thermopile outputs too much voltage, a voltage greater than 800 millivolts, for example, the controller generates the shutdown signal and closes the gas valve. The closing of the gas valve prevents gas flow to the pilot and burner, thereby preventing any combustion from occurring.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
In addition, the elevated step 30 supports a divider 60 that divides the space between the bottom of the tank 35, skirt 50, and the base pan 15 into a combustion chamber 65 (above the divider 60) and plenum 70 (below the divider 60).
A cold water inlet tube 75 and a hot water outlet tube 80 extend through a top wall of the water tank 35. A flue 85 extends through the tank 35, and water in the tank 35 surrounds the flue 85. The flue 85 includes an inlet end 90 and an outlet end 95.
The combustion chamber 65 and plenum 70 space are substantially air-tightly sealed, except for the air inlet opening 27 and inlet end 90 of the flue 85. Seals 105 between the skirt 50 and the tank 35 and base pan 15 assist in sealing the space. The seals 105 may be, for example and without limitation, fiberglass material or a high-temperature caulk material. A radiation shield 110 sits on the divider 60 within the sealed combustion chamber 65 and reflects radiant heat up toward the tank 35.
A flame arrester 115 is affixed in a sealed condition across an opening 120 in the divider 60 such that all air flowing from the plenum 70 into the combustion chamber 65 should flow through the flame arrester 115. The air inlet 27, air plenum 70, and opening 120 in the divider 60 together define an air intake for the combustion chamber 65, and air flowing into the combustion chamber 65 through the opening (see arrows in
With reference again to
A burner 155 in the combustion chamber 65 burns a mixture of fuel and air to create the products of combustion that flow up through the flue 85 to heat the water in the tank 35. The burner 155 receives fuel through a gas manifold 160 that extends in a sealed condition through an access door 165 mounted in a sealed condition over an access opening in the skirt 50.
The construction shown (illustrated in
The assembly 170 provides a flow of fuel to the pilot 185 to maintain a standing pilot burner flame, and this construction is therefore generally referred to as a “continuous pilot ignition” system. The igniter 195 is used to initiate the flame on the pilot 185 without having to reach into the combustion chamber with a match. A spark is generated by the igniter 195 in response to pushing a button on the assembly 170. The thermopile 190 provides feedback to the assembly 170 and controller 200 as to the presence of flame at the pilot 185. An exemplary thermopile 190 is a model Q313 thermopile generator manufactured by Honeywell.
The assembly 170 permits fuel to flow to the burner 155 in response to a water temperature sensor (e.g., the water temperature probe 180) indicating that the water temperature in the water tank 35 has fallen below a selected temperature. When fuel flows to the burner 155, it is mixed with air and the mixture is ignited when it contacts the pilot burner flame. Once the water temperature sensor indicates that the water has reached the desired temperature, the assembly 170 shuts off fuel flow to the burner 155, and the water heater 10 is in “standby mode” until the water temperature again drops to the point where the assembly 170 should again provide fuel to the burner 155.
An electrically controlled gas valve 205 (
The assembly 170 is shown in
In a more specific construction, the controller 200 issues a flag or signal after the output voltage traverses a first threshold voltage (e.g., about 400 millivolts). The signal can be provided to an output device (e.g., a light emitting diode, a display, an audible alarm, etc.) of the assembly 170. The controller 200 can close the gas valve 205, thereby deactivating the gas water heater 10, after the output voltage provided by the thermopile 190 traverses a second threshold voltage (e.g., about 300 millivolts). The gas valve 205 closes in response to a signal (e.g., the application or removal of a voltage, an instruction, etc.) being sent from the controller 200 to the gas valve 205.
In the construction shown in
Once the gas valve 205 closes due to a possible error condition, the gas water heater 10 will not reignite until it is serviced by the user or a serviceperson. The user or serviceperson can read the diagnostics from the controller 200 and appropriately address the condition causing the possible error condition.
As discussed above, the controller 200 can monitor a component (e.g., voltage) of the power supplied by the thermopile 190. For example, the controller 200 can monitor the voltage to determine the status of the pilot flame. For example, the controller 200 can monitor the voltage to determine whether the pilot flame indicates a normal flame burn (or normal state) or an abnormal flame burn (or fault state). The fault state can result from an improper burn by the pilot flame. Example events that may cause an improper burn can include a possible lint, dust, or oil (LDO) filter blockage event, a possible flammable vapor event, a possible improper ventilation event (e.g., the blower or exhaust system not properly discharging the exhaust), and a possible overheating event. For a specific example, a substantial blockage of the LDO filter results in an improper burn by the pilot flame, to which the voltage value provided by the thermopile 190 is reduced. When the voltage value traverses the threshold indicating a possible LDO filter blockage event, the controller 200 will take an action. The action may be providing an error output with the user interface 240 or may be providing a signal to the gas valve 205 to restrict gas to the burner 155 and/or pilot 185. Other thresholds can be used to determine other abnormal flame states. It is envisioned that the various thresholds can be determined by empirical testing and that a single threshold may be used for one or more fault states. In one construction, a nominal voltage range for the thermopile 190 is 400-800 millivolts, and consequently a range for a threshold indicating abnormal operation is between about 275 and 450 millivolts, with a preferred range of 330 and 400 millivolts. It is also envisioned that multiple thresholds can be used for a particular state—a first threshold for providing a warning and a second threshold for closing the gas valve 205.
Thus, the invention provides, among other things, a new and useful gas-fired heating device having a thermopile. Various features and advantages of the invention are set forth in the following claims.
