Patent Application
20080003530
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
In the various embodiments, a system for monitoring the operation of a fuel fired heater is provided that is capable of communicating to at least one external device. It should be noted that the system may be adapted to control the operation of any fuel-fired heating unit, such as a furnace, pool heater, or water heater appliance. In one embodiment shown in
The high temperature sensing means 124 may comprise a thermistor that is located within a combustion chamber 118 or flue 122, or mounted against an exterior surface of the combustion chamber or flue as shown in
The at least one other sensor 128 may comprise a carbon monoxide sensor capable of sensing the concentration of carbon monoxide gas, and providing an output indicative of the level of carbon monoxide (CO). The CO sensor output changes in response to sensing an increase in the presence of carbon monoxide, and the output preferably increases in response to an increase in the level of carbon monoxide gas concentration. For example, the at least one other sensor 128 may be an electrochemical sensor of the Colorimetric type that senses the build-up of CO over time and increases in resistance. One such sensor is a resettable Colorimetric Sensor Detector, which measures the build-up of CO over time. The CO sensor has a relatively low resistance when sensing less than 100 parts per million of carbon monoxide over a 90 minute period, but such resistance could rapidly increase by a factor of 3 to 1 when exposed to a carbon monoxide presence of 300 parts per million (ppm) over a 30 to 90 minute period.
The at least one other sensor 128 may also comprise a Metal Oxide Semiconductor (MOS) sensor, which may be made of a tin dioxide (SnO2) on a sintered alumina ceramic, for example. The electrical conductivity of this sensor is low in clean air, but increases when exposed to a carbon monoxide presence. The MOS CO sensor has a conductivity output that increases with a rise in carbon monoxide level, as opposed to the electrochemical sensor which has a resistance that increases with a rise in carbon monoxide level. One such sensor is a CGS-200 CO sensor manufactured by City Technology, Inc. The output of the CO sensor is preferably monitored by a microprocessor (not shown) of the controller 104, which responsively communicates a message when the sensor's output increases by more than a predetermined amount or exceeds some predetermined upper limit. In one embodiment, the predetermined amount may be a change of at least 20 percent from prior sensor readings over a time interval of less than 90 minutes.
The at least one other sensor may also comprise an electro-chemical sensor that is further capable of detecting the presence of a flammable vapor. Such a sensor may be a polymer-absorption Chemiresistor capable of changing in resistance based on the presence of a flammable vapor. One such sensor is a 25 VS sensor manufactured by Therm-O-Disc Corporation. The resistance of the sensor is about 7 to 25 kilo-ohms at 25 degrees Celsius in the absence of flammable vapors, and upon exposure to flammable vapors the resistance increases to over 100 kilo-ohms. At 50 percent of the low flammability level concentration of flammable vapors the resistance increases to at or near 50 kilo-ohms, preferably within about 60 seconds. It should be noted that the at least one other sensor 128 may comprise two or more of the above sensors for detecting the presence of one or more gasses within or around the appliance. Likewise, the at least one other sensor 128 may be two or more integral sensors for sensing the presence of one or more respective gasses. One example of such a sensor is the IRcel™ non-dispersive infrared gas sensor for detecting both carbon dioxide and hydrocarbons, which is manufactured by City Technology, Inc.
The controller 104 is configured to monitor (via the microprocessor) the at least one other sensor 128 that is capable of detecting the presence of a flammable vapor, and responding by communicating a message of the abnormal condition of a presence of a flammable vapor near the fuel fired appliance 112. For example, an occupant could be alerted of a potential fire hazard, through the detection of a flammable vapor concentration that is greater than 50 percent of the lower flammability level by the at least one other sensor 128. The controller 104 responds by wirelessly transmitting a signal that includes a message indicating an abnormal concentration of flammable vapor present near the water heater appliance 112. The controller 104 can also communicate the abnormal condition of a high temperature in the combustion chamber or flue 118, which could be indicative of a blocked flue that might cause carbon monoxide to collect near the appliance 112. Likewise, the controller 104 can also communicate the abnormal condition of a harmful level of carbon monoxide gas near the appliance 112. The controller 104 may, for example, be configured to respond to the detection of at least 100 parts per million of carbon monoxide gas in a 90 minute period by the at least one other sensor 128 by wirelessly transmitting a signal including a message indicating an abnormal condition of a harmful level of carbon monoxide gas.
In the first embodiment, the controller 104 further comprises a transmitter module 130 for wirelessly transmitting digital signals. The signals wirelessly transmitted by the controller 104 are preferably received by an external device 140 such as a thermostat for alerting an occupant. The thermostat 140 is configured to receive the wirelessly transmitted signal and immediately display a text message on a display device 144 on the thermostat 140. The thermostat 140 accordingly provides for displaying the abnormal condition for the fuel fired water heater appliance 112, to alert an occupant in the space of the abnormal condition.
The signal transmitted to an external device 140 (such as a thermostat) includes a message communicated by the controller 104 that includes information relating to the abnormal condition. The transmitted message may include a text message that is displayed in its entirety by a display device of the thermostat 140. In the first embodiment of a system 100, the message is displayed by the thermostat 140 independent of any input from a user, such that an occupant may be alerted of an abnormal condition without the occupant having to prompt the thermostat for information about the appliance.
Referring to
In the first embodiment, the wireless transmitter device or module 130 may be a low-power, short-range radio Local Area Network (LAN), which is in communication with a thermostat 140 that is also connected to the LAN. One such thermostat 140 that may be connected to a LAN is disclosed in U.S. patent application Ser. No. 11/156,391, filed on Jun. 20, 2005, entitled “Thermostat capable of displaying received information”, which is incorporated herein by reference in its entirety. In one embodiment, the transmitter 130 associated with the controller 104 for the fuel-fired water heating appliance 112 preferably comprises a wireless LAN IC chip such as a PRISM 3.0 802.11b wireless LAN chip set. Alternatively, the transmitter device 130 may be an AirWave WiFi wireless LAN, AW-ST-CB-EA-RS232 sold by Alpine Technology Ltd. Other commercially available wireless LAN devices include the Actiontec Mini 802.11B Modem Combo Card manufactured by Actiontec. The wireless LAN chip may be in communication with an antenna device that is either trace mounted on a circuit board of the controller 104 or the transmitter module 130, or externally mounted. The LAN transceiver 130 is preferably configured to communicate via a 9-pin RS-232 interface the microprocessor of the fuel-fired water heater controller 104. The microprocessor of the controller 104 preferably includes a UART digital data signal output for communicating signals to the transmitter device 130. The controller 104 may respond to a sensed abnormal condition by commencing successive wireless transmissions of a signal including a message indicating the presence of an abnormal condition. The controller 104 may also continuously re-transmit the message at predetermined intervals, to assure that the signal may be reliably received by the thermostat 140. Thus, the microprocessor of the controller 104 may communicate a message to the transmitter device 130, which accordingly transmits a signal including the message indicating an abnormal condition of the appliance via the LAN connection with the thermostat 140.
In a second embodiment shown in
In the second embodiment, the transmitter module 230 preferably comprises an RF transceiver module. The controller 204 and transceiver module 230 are capable of continuously transmitting a message at predetermined intervals, to assure that the signal may be properly received by the thermostat 240. The transmitter device 230 is in communication with an antenna device 232 that is either trace mounted on a circuit board of the controller 204 or a transmitter circuit 234, or externally mounted. The transmitter module 230 is configured to transmit at a frequency in the range of about 915 to 918 megahertz (MHz), but may alternatively transmit at other frequencies suitable for achieving wireless communication across the same distance. Such devices communicate across relatively closed distances of 20 to 40 feet, and typically operate at a low power transmission levels (under 1 watt) that fall within the un-licensed Federal Communications Commission (FCC) part 15 rules that limit maximum transmission power or field strength. In addition, FCC regulations limit some devices to communicating only once in a 100 millisecond interval. However, the FCC Part 15 rules permit a number of “periodic” devices to transmit on certain permitted frequencies at a much higher transmission power. Such devices may include signaling devices with very limited transmission times of not more than 5 seconds duration, for signaling an alarm during emergency situations involving fire or safety of life. The transceiver module 230 is preferably configured to transmit at a variable power level, which power level may be controlled by an external input to the transceiver. Such an external input could be provided by the microprocessor 208 of the controller 204, for establishing “periodic” transmissions of signals upon sensing an abnormal condition. The RF transceiver is generally capable of transmitting signals at a frequency of about 915 to 917 MHz, at a power level of less than 1 watt. It should be noted that the RF transceiver 230 may alternately be configured to transmit at 433 MHz, or any other frequency suitable for wireless communication across the present short range distance. The RF transceiver 230 is also configured to make “periodic” transmissions of signals at peak power transmission levels above 1 watt for a duration not more than 5 seconds (which is above the FCC limit), where the signal includes a message indicating an abnormal condition that involves a potential fire hazard or safety of life. This provides an effective transmission signal strength for reliably propagating signals and improving the likelihood that the signal will be reliably received by an external device such as a thermostat 240, for alerting an occupant of an abnormal condition.
One example of an RF transceiver 230 that is capable of transmitting at frequencies in the range of 915 to 917 MHz, at varying power levels is a TXM-916-ES RF Module manufactured by LINX Technologies, Inc. This RF Module includes an input for receiving a digital signal (such as from a UART output of the microprocessor 208), and an LADJ input for external adjustment and control of the transmit power up to a maximum of 7 milliamperes (+4 dBm). Another example of a transmitter 230 is a CC1070 wireless RF transmitter manufactured by Chipcon AS, of Germany. This RF transmitter also has a programmable output transmit power of up to a maximum of 28 milliamperes (+8 dBm). This transmitter includes a PA_Power bit register that can be set (by microprocessor 208 for example) to change the output transmit power. Where the transceiver module 230 is further capable of receiving signals, the controller 204 or microprocessor 208 may prohibit the reception of wireless transmissions by the transceiver 230 while an abnormal condition has been detected, to establish priority for transmission of signals indicating the presence of an abnormal condition. Accordingly, the controller 204 provides for detecting an abnormal condition and responding by wirelessly transmitting a signal indicating the abnormal condition to alert an occupant of the abnormal condition.
The advantages of the above described embodiment and improvements should be readily apparent to one skilled in the art, as to enabling communication from fuel-fired heating systems to other external devices. Additional design considerations may be incorporated without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited by the particular embodiment or form described above, but by the appended claims.
