Thermostat with replaceable carbon monoxide sensor module

A thermostat is provided that includes a peripheral edge that, at least in part, defines an opening in the thermostat. The thermostat further includes a carbon monoxide sensor capable of sensing the presence of carbon monoxide gas in the ambient air near the thermostat, and providing a measurable output value that is indicative of the level of carbon monoxide gas. The thermostat also includes a replaceable battery that applies a voltage to the carbon monoxide sensor. The thermostat further includes a microprocessor disposed on a circuit board. The circuit board, sensor and battery are together disposed on or in the thermostat. The circuit board is configured to establish an electrical connection with the carbon monoxide sensor and the battery. The microprocessor is configured to periodically read the carbon monoxide sensor output, and to activate an audible alarm in a continuous manner to indicate an emergency upon detecting a carbon monoxide level that exceeds a predetermined value.

FIELD

The present disclosure relates to thermostats, and more particularly to sensors within digital thermostats for sensing carbon monoxide in occupied environments.

BACKGROUND

Although smoke detectors are typically installed throughout the home, carbon monoxide detectors are often only installed in a basement or utility room that encloses a furnace or water heater. While useful for their intended purpose of detecting carbon monoxide in the basement, such installations do not monitor the spaces occupied by persons in the home. This would require the installation within the occupied space of an additional sensor, which some occupants consider to be unsightly as well as costly.

SUMMARY

The present application discloses various embodiments of a wall-mounted thermostat that includes a replaceable carbon monoxide sensor that is independent from but located with or on a thermostat. In one embodiment, a thermostat is provided that includes a housing having at least one peripheral edge that, at least in part, defines an opening that provides access to the interior space of the thermostat. The thermostat further includes an access cover for covering the opening in the thermostat. The access cover is removably attached to the thermostat, to thereby allow the access cover to be removed to permit access to the interior space of the thermostat.

The thermostat further includes a carbon monoxide sensor capable of sensing the presence of carbon monoxide gas in the ambient air near the thermostat, and providing a measurable output value that is indicative of the level of carbon monoxide gas. The thermostat also includes a replaceable battery that applies a voltage to the carbon monoxide sensor. The thermostat further includes a microprocessor disposed on a circuit board that is secured within the interior space of the thermostat, adjacent the opening. The circuit board is configured to establish an electrical connection with the carbon monoxide sensor and the battery, which electrical connection permits the microprocessor to monitor the output value of the carbon monoxide sensor that has been inserted and/or connected to the circuit board. The microprocessor is configured to periodically read the carbon monoxide sensor output, and is further configured to activate an audible alarm in a continuous manner to indicate an emergency upon detecting an output value from the carbon monoxide sensor that exceeds a predetermined value.

DETAILED DESCRIPTION

Referring toFIGS. 1-3, a first embodiment of thermostat100is shown. The thermostat100includes a housing104having at least one peripheral portion108that, at least in part, defines an opening110in the thermostat100, which provides access to the interior space112of the thermostat (SeeFIG. 3). The thermostat100further includes an access cover116for covering the opening110in the thermostat100. The access cover116is removably attached to the thermostat100, to thereby allow the access cover116to be removed to permit access to the interior space112of the thermostat100.

The thermostat100further includes a carbon monoxide sensor122capable of sensing the presence of carbon monoxide gas in the ambient air near the thermostat100. The carbon monoxide sensor122is configured to provide a measurable output value that is indicative of the level of carbon monoxide gas. The thermostat100also includes a replaceable battery124that applies a voltage to the carbon monoxide sensor122. The thermostat100further includes a microprocessor128disposed on a circuit board126that is secured within the interior space112of the thermostat100, adjacent the opening110and between the base portion102and thermostat cover104. The circuit board126is configured to establish an electrical connection with the carbon monoxide sensor122and the battery124, which electrical connection permits the microprocessor128to monitor the output value of the carbon monoxide sensor122that has been inserted and/or connected to the circuit board126. The microprocessor128is configured to periodically read the carbon monoxide sensor output, and is further configured to activate a speaker132to provide an audible alarm in a continuous manner to indicate an emergency upon detecting an output value from the carbon monoxide sensor122that exceeds a predetermined value. The microprocessor128may also activate the emergency alarm where the sensor's output value changes by at least a 50 percent over a prior sensor output value received within a period of time of between about 15 to 90 minutes. The microprocessor128, which is in communication with the carbon monoxide sensor122, thus provides an audible emergency alarm signal to alert an occupant of the presence of a harmful level of carbon monoxide gas (a harmful level of carbon monoxide gas may be the presence of at least 300 parts per million of carbon monoxide gas, for example).

This embodiment of a thermostat100with an integral or co-located carbon monoxide sensor122is advantageous because it is configured to provide an emergency alarm upon detecting a harmful level of carbon monoxide gas in the ambient air surrounding the thermostat100where the occupants are. Positioning the carbon monoxide sensor122on the thermostat100ensures that the sensor is positioned properly to sense the level of carbon monoxide in the space that is being occupied, rather than at the location of a furnace or water heater in a basement or garage. The carbon monoxide sensor122is also protected by the thermostat housing104against exposure to water or humidity that could cause the carbon monoxide sensor122to become inoperable or provide an inaccurate reading. Accordingly, the thermostat100provides the advantage of including an integral or co-located carbon monoxide sensor122for detecting the presence of carbon monoxide within the space that is being occupied by humans, rather than that of a basement or separate furnace/utility room. The thermostat100and co-located carbon monoxide sensor122also provide an audible emergency alarm which can be easily heard within the space being occupied, unlike carbon monoxide sensors located in a basement or separate furnace/utility room which cannot be readily heard. The inclusion of the carbon monoxide sensor122within the thermostat100would also provide a less costly and more appealing alternative to a stand-alone sensor. Also, the location of the sensor with or on the thermostat provides easy access to the carbon monoxide sensor for inspection, periodic operational testing, and replacement by the user, and would be more easily replaced by elderly persons than a separate carbon monoxide sensor mounted on a wall that may require the aid of a ladder.

Preferably, the carbon monoxide sensor122provides an output value that changes in response to sensing an increase in the presence of carbon monoxide gas. For example, the carbon monoxide sensor122may be an electrochemical sensor of the Colorimetric type that senses the build-up of carbon monoxide over time and increases in resistance in response to an increase in the level of carbon monoxide gas concentration. Such a sensor could be a Colorimetric sensor detector, which measures the build-up of carbon monoxide over time, and may take up to 48 hours to reset. For example, where a typical carbon monoxide sensor may have a low resistance when sensing less than 100 parts per million of carbon monoxide over a 90 minute period, 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 carbon monoxide sensor122may also be a Metal Oxide Semiconductor (MOS) sensor, which may be made of a tin dioxide (SnO2) on a sintered alumina ceramic, for example. One example of a MOS carbon monoxide sensor may be a CGS-200 CO sensor manufactured by City Technology. In the case of a Metal Oxide Semiconductor (MOS) carbon monoxide sensor, the electrical conductivity is low in clean air, but the conductivity increases when exposed to a carbon monoxide presence. The MOS carbon monoxide sensor accordingly has a conductivity output that increases (or a resistance that decreases) with carbon monoxide level, as opposed to the electrochemical sensor which has a resistance that increases with carbon monoxide level. The MOS carbon monoxide sensors offer the ability to detect low (0-100 ppm) concentrations of carbon monoxide gases over a wide temperature range. Accordingly, the measurable output value of the replaceable carbon monoxide sensor122may be a resistance value that increases with an increase in the level of carbon monoxide, or may be a resistance value that decreases with an increase in the level of carbon monoxide. The measurable output value of the replaceable carbon monoxide sensor122may also be a voltage drop across the replaceable carbon monoxide sensor122, where the voltage may change by at least 50 percent within a period of time of between about 15 to 90 minutes upon exposure to a level of carbon monoxide of at least 300 parts per million. The carbon monoxide sensor122may also comprise an electrolyte solution, such as a water based gel MicroSir sensor manufactured by Quantum Group, as disclosed in U.S. Pat. No. 6,998,991.

However, it has been observed that carbon monoxide sensors may undergo changes in resistance due to general ageing, even in a mild environment. Electro-chemical sensors may dry out, or may erode as a result of chemical vapors, e.g., chlorines commonly found in household bleaches. Over time, a carbon monoxide sensor may gradually increase in resistance sufficient to cause a false shut-down of a furnace system. On the other hand, the resistance of a carbon monoxide sensor may diminish gradually over time due to other circumstances, possibly to such a low level that it might not trip a shut-down of a heating system if a harmful level of carbon monoxide gas were to occur. Some sensors encounter an output increase with an increase in humidity, and sensor output may fall to zero even in the presence of gas when humidity drops to very low levels. Environmental exposure of the sensor and the effects of humidity on sensor output can lead to difficulties in the interpretation of positive readings of the sensor. Accordingly, the output of such carbon monoxide sensors will not be reliable after a given period of time of continuous use.

To address this concern, the first embodiment of a thermostat100includes a replaceable carbon monoxide sensor122that is configured to be removably inserted through the opening110leading into the interior space112of the thermostat100. The thermostat100also includes a replaceable battery124that applies a voltage to the replaceable carbon monoxide sensor122, where the battery124is also configured to be removably inserted through the opening110in the thermostat100. The thermostat100further includes a microprocessor128disposed on a circuit board126that is secured within the interior space112of the thermostat100, adjacent the opening110. The thermostat100has a separate circuit (not shown) that operates independent of the stand-alone circuit board126and microprocessor128, which may be removed or replaced without interfering with the operation of the thermostat100. The circuit board126includes a receptacle130configured to releasably receive the replaceable carbon monoxide sensor122and the battery124in a manner that establishes electrical connection between the carbon monoxide sensor122, battery124and the circuit board126.

The replaceable carbon monoxide sensor122is configured to provide a signal or a measurable output value that is indicative of the level of carbon monoxide presence in the ambient air surrounding the thermostat100, where the output or measurable value changes over time due to the nature of the sensor. With Electro-chemical or Metal Oxide Semiconductor (MOS) carbon monoxide sensors, continuous use of the sensor over an extended period of time causes the sensor's nominal output value to change substantially over time. Since a certain conductivity or resistance level of the sensor is typically relied upon for indicating the presence of a harmful level of carbon monoxide gas (such as 400 parts per million, for example), a substantial change in the sensor's conductivity or resistance over time would accordingly cause the replaceable carbon monoxide sensor122to become subject to providing output values that would be unreliable after a given time period of use. Similarly, the resistive value of some carbon monoxide sensors may change relative to the ambient temperature that the sensor is exposed to. Since a certain resistance level of the sensor is typically relied upon for indicating the presence of a harmful level of carbon monoxide gas, a shift in the sensor's resistance due to a warm ambient temperatures in high ceiling areas, or cooler ambient temperatures in basement areas could accordingly cause the replaceable carbon monoxide sensor122to become subject to providing inconsistent or unreliable output values.

Accordingly, the microprocessor128on the circuit board126is configured to monitor the carbon monoxide sensor122and to responsively activate a speaker132to provide a service alarm when the microprocessor128detects that the replaceable carbon monoxide sensor122has exceeded a predetermined duration of use. The predetermined duration of use may be, for example, a period of at least 4 years. The microprocessor128thereby prompts a user to replace the replaceable carbon monoxide sensor122with a new carbon monoxide sensor (not shown). The access cover116is releasably attached to the thermostat100to permit access to the interior space112, to thereby allow for the removal of the battery124and the replaceable carbon monoxide sensor122for replacement thereof. In the thermostat100shown inFIGS. 1-3, the replaceable carbon monoxide sensor122, battery124and stand-alone circuit board126are located completely within the interior space112of the thermostat100. This provides the advantage of a thermostat100including an integral or co-located replaceable carbon monoxide sensor122for detecting the presence of carbon monoxide within the space that is being occupied by humans (rather than that of a basement or separate furnace/utility room), which also prompts the user to replace the replaceable carbon monoxide sensor122upon determining that the carbon monoxide sensor is no longer reliable, such that the occupants are provided with reliable protection against the danger of carbon monoxide gas within the home.

The thermostat100with a replaceable carbon monoxide sensor122also provides an additional function beyond that of the sensor's function of detecting a harmful level of carbon monoxide gas, in locating the carbon monoxide sensor122in a location where ambient temperatures will be maintained relatively constant by the thermostat100. By positioning the carbon monoxide sensor within the thermostat. Unlike ceiling areas where temperatures tend to increase as heat rises, or basement areas that tend to be cooler or subject to humidity, the present carbon monoxide sensor122located within the thermostat100is exposed to a relatively consistent ambient temperature that is maintained by the thermostat100. In this manner, the resistive output of the carbon monoxide sensor122is more consistent, and less likely to be affected by temperature. Since a certain resistance level of the sensor is typically relied upon for indicating the presence of a harmful level of carbon monoxide gas, the thermostat100of the present invention provides the added function of ensuring that the carbon monoxide sensor122is exposed to a consistent ambient temperature, so as to provide for more reliable sensor operation.

Additionally, the thermostat100having a replaceable carbon monoxide sensor122provides an additional function beyond that of the sensor's function of detecting a harmful level of carbon monoxide gas. The thermostat100is configured to provide the added function of permitting heating operation only when the carbon monoxide sensor122and battery124are installed, as explained below.

The thermostat100may comprise a mechanical switch activated by displacement of a lever140, which is positioned within the interior space112of the thermostat, such that the lever140closes the switch only when the carbon monoxide sensor122and battery124are installed or received within the connector130. Similarly, the switch could comprise a photo-optic emitter and collector positioned on opposite sides of the battery, for example, which would activate a switch when the battery is present between the emitter and collector. Alternatively, the thermostat100may employ a lever140that is displaced upon installation of the carbon monoxide sensor122and battery124, where the cover116can only be attached upon displacement of the lever140. The cover116could then cause a switch or electrical connection to occur upon attachment to the thermostat100.

In the thermostat embodiment100shown inFIG. 3, the lever140preferably establishes electrical connection between the battery124and a thermostat control circuit associated with a circuit board142. In this manner, the thermostat100would accordingly sense the presence of a voltage via the lever140when a battery124is received within the connector130. When the carbon monoxide sensor122and battery124are installed (or alternatively when access cover116is attached), a switch or electrical connection occurs, which establishes a voltage that is detected by the control circuit associated with the circuit board142for controlling the thermostat's operation. The thermostat100enables heating operation only when this voltage is present and detected by the circuit board142. Without installation of the carbon monoxide sensor122and battery124, the disabled switch or lack of a connection would cause the thermostat to be incapable of operating the heating system. This ensures that a fuel-fired heating system would only be operated when a carbon monoxide sensor122and battery124have been installed, to provide for proper monitoring of carbon monoxide that may be produced by the fuel-fired heating system. Similarly, where the installed battery voltage is below a minimum detectable level, the thermostat control circuit associated with the circuit board142for controlling the thermostat100is configured to display a low battery indication and alter the temperature setting of the thermostat100. The altered temperature setting may be a setting of 60 degrees Fahrenheit, for example, which would urge an occupant to check the thermostat and discover the display of a low level condition for the carbon monoxide sensor battery124. Where the thermostat100does not detect the presence of a sufficient voltage via the electrical connection to the circuit board142, the thermostat would not operate the heating system. This ensures that a fuel-fired heating system would only be operated when the battery124associated with the carbon monoxide sensor122has a sufficient voltage level to provide for proper monitoring of carbon monoxide that may be produced by the fuel-fired heating system.

Accordingly, the thermostat100and replaceable carbon monoxide sensor122provide an additional function beyond that of the sensor's function of detecting a harmful level of carbon monoxide gas, in preventing operation of a heating system that could produce carbon monoxide gas unless a carbon monoxide sensor122and battery124with a sufficient voltage level are installed. This ensures that the heating system will only be operated during periods when the carbon monoxide sensor is present and operating, to thereby monitor for carbon monoxide that may be produced by the fuel-fired heating system, which function is not provided by other commercially available carbon monoxide sensors.

In the above embodiment, the microprocessor128may be further configured to activate an audible service alarm output upon detecting that the battery level is below a predetermined threshold. While the thermostat100depicted inFIGS. 1-2shows the replaceable carbon monoxide sensor122as being removable, alternatively, the circuit board126, the replaceable carbon monoxide sensor122and battery124may all be removable through the opening110, to thereby permit replacement of both the circuit board126and carbon monoxide sensor122together.

In an alternate embodiment, a thermostat may be provided that includes a microprocessor128disposed on a circuit board126(within the interior of the thermostat), which periodically reads the output value of the replaceable carbon monoxide sensor122and stores at least one output value of the carbon monoxide sensor122in a memory. In some embodiments, the microprocessor128responsively activates a service alarm when the microprocessor128detects that the sensor output value has changed by more than a predetermined amount over at least one previously stored sensor output value.

In a second embodiment shown inFIG. 4, the thermostat200includes a housing204having at least one peripheral edge208that defines, at least in part, an opening210in the thermostat200which provides access to the interior space212of the thermostat200. The thermostat200further includes a replaceable carbon monoxide sensor module220that is disposed within the interior space212of the thermostat200. The replaceable carbon monoxide sensor module220is configured to be removably received within the thermostat200through the opening210. The replaceable carbon monoxide sensor module220includes a circuit board226having a connector or receptacle230thereon, a replaceable battery224configured to be releasably received within the receptacle230, and a replaceable carbon monoxide sensor222configured to be releasably received within the receptacle230in a manner that establishes electrical connection between the battery224, the carbon monoxide sensor222and the circuit board226. The replaceable carbon monoxide sensor222provides a measurable output value that is indicative of the level of carbon monoxide gas in the ambient air surrounding the thermostat200. The nature of the replaceable carbon monoxide sensor222is such that continuous use of the sensor over an extended period of time causes the sensor's nominal output value to change substantially over time. The replaceable carbon monoxide sensor module220further includes a microprocessor228disposed on the circuit board226that is configured to activate a speaker232to provide continuous audible alarm to indicate an emergency upon detecting a sensor output value indicative of a harmful level of carbon monoxide gas (a harmful level of carbon monoxide gas may be the presence of at least 300 parts per million of carbon monoxide gas, for example). The microprocessor228is also configured to monitor the replaceable carbon monoxide sensor222and to activate an intermittent audible service alarm when the replaceable carbon monoxide sensor222has exceeded a predetermined duration of use, to thereby prompt a user to remove and replace the replaceable carbon monoxide sensor module220. The predetermined duration of use may be, for example, a period of at least 4 years.

Accordingly, the microprocessor228thereby prompts a user to replace the replaceable carbon monoxide sensor module220with a new carbon monoxide sensor module220. The cover216on the carbon monoxide sensor module220is releasably attached to the thermostat200to permit access to the interior space212, to thereby allow for the removal of the battery224and the replaceable carbon monoxide sensor module220for replacement thereof. In the thermostat200shown inFIG. 4, the replaceable carbon monoxide sensor module220is located completely within the interior space212of the thermostat200. This provides the advantage of including an integral or co-located replaceable carbon monoxide sensor module220for detecting the presence of carbon monoxide within the space that is being occupied by humans (rather than that of a basement or separate furnace/utility room), which also prompts the user to replace the replaceable carbon monoxide sensor module220upon determining that the carbon monoxide sensor222is no longer reliable, such that the occupants are provided with reliable protection against the danger of carbon monoxide gas within the home.

In the second embodiment, the microprocessor228may be further configured to activate an audible service alarm upon detecting that the battery level is below a predetermined threshold. The thermostat200that is depicted inFIG. 4shows the replaceable carbon monoxide sensor module220with a carbon monoxide sensor222and battery224that are together removably received through the opening210within the thermostat200. Alternatively, a third embodiment of a thermostat300, as shown inFIG. 5, may have a portion of the replaceable carbon monoxide sensor module220, and the cover portion216attached thereto, that extend outside of the opening210and protrude from the thermostat housing204, which provides a grip portion that can aid a user in the replacement of the carbon monoxide sensor module220.

In a fourth embodiment shown inFIG. 6, the thermostat400includes a housing having a front surface404and at least one peripheral edge508that defines, at least in part, an opening (not shown) in the thermostat400. A replaceable carbon monoxide sensor module420is provided, which is disposed adjacent to the thermostat400. The replaceable carbon monoxide sensor module420has a portion that is configured to be removably received within the opening in the housing404, so as to abut to the peripheral edge408of the thermostat400in a manner such that the replaceable carbon monoxide sensor module420is positioned against the peripheral edge408of the housing404. In this manner, the replaceable carbon monoxide sensor module420and the thermostat housing404thereby form a single unit. Much like the above embodiments, the replaceable carbon monoxide sensor module420further includes a circuit board having a receptacle thereon, and a replaceable battery configured to be releasably received within the receptacle. On the circuit board is a replaceable carbon monoxide sensor that is configured to be releasably received within the receptacle in a manner that establishes electrical connection between the battery, the carbon monoxide sensor and the circuit board. The replaceable carbon monoxide sensor provides a measurable output value that is indicative of the level of carbon monoxide gas in the ambient air surrounding the thermostat, and continuous use of the sensor over an extended period of time causes the sensor's nominal output value to change substantially over time. The circuit board includes a microprocessor that is configured to activate a continuous audible alarm to indicate an emergency upon detecting a sensor output value indicative of a harmful level of carbon monoxide gas (a harmful level of carbon monoxide gas may be the presence of at least 300 parts per million of carbon monoxide gas, for example). The microprocessor is configured to monitor the replaceable carbon monoxide sensor and to activate an intermittent audible service alarm when the replaceable carbon monoxide sensor has exceeded a predetermined duration of use, to thereby prompt a user to remove and replace the replaceable carbon monoxide sensor module.

Accordingly, the microprocessor thereby prompts a user to replace the replaceable carbon monoxide sensor module420with a new carbon monoxide sensor module420. The carbon monoxide sensor module420is releasably attached to the thermostat400, to thereby allow for the removal of the carbon monoxide sensor module420for replacement thereof. In the thermostat400shown inFIG. 6, the replaceable carbon monoxide sensor module420is located on the thermostat400adjacent a peripheral edge408so as to form a single unit. This provides the advantage of including an integral or co-located replaceable carbon monoxide sensor module420for detecting the presence of carbon monoxide within the space that is being occupied by humans (rather than that of a basement or separate furnace/utility room). The replaceable carbon monoxide sensor module420also prompts the user to replace the replaceable carbon monoxide sensor module420upon determining that the carbon monoxide sensor is no longer reliable, such that the occupants are provided with reliable protection against the danger of carbon monoxide gas within the home.

Referring toFIG. 7, a fifth embodiment of a thermostat and replaceable carbon monoxide sensor is shown. The thermostat500includes a housing504having an opening in a peripheral side thereof, which provides access to the interior space of the thermostat, and a thermostat control circuit (not shown) within the housing504for controlling operation of at least a heating system. As shown inFIG. 7, the housing504has at least one peripheral portion508that, at least in part, defines an opening510in the thermostat500, which provides access to the interior space512of the thermostat. The thermostat500further includes an access cover516for covering the opening510in the thermostat500. The access cover516is removably attached to the thermostat500, to thereby allow the access cover516to be removed to permit access to the interior space512of the thermostat500.

The thermostat further includes a carbon monoxide sensor circuit comprising a circuit board554having a connector552thereon, the circuit board and connector552being disposed within the interior space512of the thermostat500. The thermostat further includes a replaceable carbon monoxide sensor522and a battery524that applies a voltage to the replaceable carbon monoxide sensor522. The replaceable carbon monoxide sensor522and battery524are configured to be to be removably inserted through the opening510into the interior space of the thermostat, and to be connected to the connector544. The access cover516may also be connected to the circuit board526on which the battery524and replaceable carbon monoxide sensor522are disposed, and may be attached or connected simultaneously with the circuit board526to the thermostat500.

The thermostat500further includes a carbon monoxide sensor522capable of sensing the presence of carbon monoxide gas in the ambient air near the thermostat500. The carbon monoxide sensor522is configured to provide a measurable output of the sensed level of carbon monoxide gas that changes substantially with continuous use of the sensor over an extended period of time. The thermostat500also includes a replaceable battery524that applies a voltage to the carbon monoxide sensor522. The thermostat500further includes a circuit board526that is inserted within the thermostat500, adjacent the opening510in the thermostat cover504. The circuit board526is configured to establish an electrical connection with the carbon monoxide sensor522and the battery524, which electrical connection permits the circuit board528to monitor the output value of the carbon monoxide sensor522. The circuit board526has a connector550that is configured to establish connection with the connector552of carbon monoxide sensor circuit554. The circuit board526is configured to periodically read the carbon monoxide sensor output, and is further configured to activate a speaker532to provide an audible alarm in a continuous manner to indicate an emergency upon detecting an output value from the carbon monoxide sensor522that exceeds a predetermined value. The microprocessor528may also activate the emergency alarm where the sensor's output value changes by at least a 50 percent over a prior sensor output value received within a period of time of between about 15 to 90 minutes. The microprocessor528, which is in communication with the carbon monoxide sensor522, thus provides an audible emergency alarm signal to alert an occupant of the presence of a harmful level of carbon monoxide gas.

The thermostat further includes a detection means540for detecting when the replaceable carbon monoxide sensor component520is installed within the interior of the thermostat, and providing an input to the thermostat control circuit554when the replaceable carbon monoxide sensor is installed within the interior of the thermostat. The thermostat control circuit (not shown) disables operation of the heating system when the replaceable carbon monoxide sensor component520is not installed, to thereby ensure that the heating system is operated only when said replaceable carbon monoxide sensor is present.

The detection means540may comprise a mechanical switch activated by displacement of a lever540, which is positioned within the interior space512of the thermostat, such that the lever540closes the switch only when the carbon monoxide sensor522and battery524are installed or received within the connector530. Similarly, the switch could comprise a photo-optic emitter and collector positioned on opposite sides of the battery, for example, which would activate a switch when the battery is present between the emitter and collector. Alternatively, the thermostat500may employ a lever540that is displaced upon installation of the carbon monoxide sensor522and battery524, where the cover516can only be attached upon displacement of the lever540. The cover516could then cause a switch or electrical connection to occur upon attachment to the thermostat500.

In the thermostat embodiment500shown inFIG. 7, the lever540preferably establishes electrical connection between the battery524and a thermostat control circuit associated with a circuit board542. In this manner, the thermostat500would accordingly sense the presence of a voltage via the lever540when a battery524is received within the connector530. When the carbon monoxide sensor522and battery524are installed (or alternatively when access cover516is attached), a switch or electrical connection occurs, which establishes a voltage that is detected by the control circuit associated with the circuit board542for controlling the thermostat's operation. The thermostat500enables heating operation only when this voltage is present and detected by the circuit board542. Without installation of the carbon monoxide sensor522and battery524, the disabled switch or lack of a connection would cause the thermostat to be incapable of operating the heating system. This ensures that a fuel-fired heating system would only be operated when a carbon monoxide sensor522and battery524have been installed, to provide for proper monitoring of carbon monoxide that may be produced by the fuel-fired heating system. Similarly, where the installed battery voltage is below a minimum detectable level, the thermostat control circuit associated with the circuit board542for controlling the thermostat500is configured to display a low battery indication and alter the temperature setting of the thermostat500. The altered temperature setting may be a setting of 60 degrees Fahrenheit, for example, which would urge an occupant to check the thermostat and discover the display of a low level condition for the carbon monoxide sensor battery524. Where the thermostat500does not detect the presence of a sufficient voltage via the electrical connection to the circuit board542, the thermostat would not operate the heating system. This ensures that a fuel-Tired heating system would only be operated when the battery524associated with the carbon monoxide sensor522has a sufficient voltage level to provide for proper monitoring of carbon monoxide that may be produced by the fuel-fired heating system.

Accordingly, the thermostat500and replaceable carbon monoxide sensor522provide an additional function beyond that of the sensor's function of detecting a harmful level of carbon monoxide gas, in preventing operation of a heating system that could produce carbon monoxide gas unless a carbon monoxide sensor522and battery524with a sufficient voltage level are installed. This ensures that the heating system will only be operated during periods when the carbon monoxide sensor is present and operating, to thereby monitor for carbon monoxide that may be produced by the fuel-fired heating system, which function is not provided by other commercially available carbon monoxide sensors.

In the above embodiment, the microprocessor528may be further configured to activate an audible service alarm output upon detecting that the battery level is below a predetermined threshold. While the thermostat500depicted inFIG. 7shows the replaceable carbon monoxide sensor522as being removable, alternatively, the circuit board526, the replaceable carbon monoxide sensor522and battery524may all be removable through the opening510, to thereby permit replacement of both the circuit board526and carbon monoxide sensor522together.

In a sixth embodiment shown inFIG. 8, the thermostat600includes a housing602having a front surface604and at least one peripheral edge608that include, at least in part, openings on at least two sides (front and side) of the thermostat600. The openings on at least two sides of the thermostat are configured to define a pocket or slot opening in the front of the thermostat. The pocket or slot opening extends horizontally across front of the thermostat600, and a replaceable carbon monoxide sensor module620is disposed within the pocket/slot opening. The replaceable carbon monoxide sensor module620is configured to be removably received within the slot opening in the housing602in a manner such that the entire replaceable carbon monoxide sensor module620fits within the pocket opening/slot, and is flush with the front surface604and peripheral edge608of the housing602. In this manner, the replaceable carbon monoxide sensor module620and the thermostat housing602thereby form a single unit. Much like the above embodiments, the replaceable carbon monoxide sensor module620further includes a circuit board having a receptacle thereon, and a replaceable battery configured to be releasably received within the receptacle. On the circuit board is a replaceable carbon monoxide sensor that is configured to be releasably received within the receptacle in a manner that establishes electrical connection between the battery, the carbon monoxide sensor and the circuit board. The replaceable carbon monoxide sensor provides a measurable output value that is indicative of the level of carbon monoxide gas in the ambient air surrounding the thermostat, and continuous use of the sensor over an extended period of time causes the sensor's nominal output value to change substantially over time. The circuit board includes a microprocessor that is configured to activate a continuous audible alarm to indicate an emergency upon detecting a sensor output value indicative of a harmful level of carbon monoxide gas (a harmful level of carbon monoxide gas may be the presence of at least 300 parts per million of carbon monoxide gas, for example). The microprocessor is configured to monitor the replaceable carbon monoxide sensor and to activate an intermittent audible service alarm when the replaceable carbon monoxide sensor has exceeded a predetermined duration of use, to thereby prompt a user to remove and replace the replaceable carbon monoxide sensor module.

Accordingly, the microprocessor thereby prompts a user to replace the replaceable carbon monoxide sensor module620with a new carbon monoxide sensor module620. The carbon monoxide sensor module620is releasably attached to the thermostat600, to thereby allow for the removal of the carbon monoxide sensor module620for replacement thereof. In the thermostat600shown inFIG. 6, the replaceable carbon monoxide sensor module620is located on the thermostat600flush with the front and the peripheral edge608so as to form a single unit. This provides the advantage of including an integral or co-located replaceable carbon monoxide sensor module620for detecting the presence of carbon monoxide within the space that is being occupied by humans (rather than that of a basement or separate furnace/utility room). The replaceable carbon monoxide sensor module620, which includes a battery, a carbon monoxide sensor and a microprocessor in connection with the battery and carbon monoxide sensor, may be removed and replaced with a new replaceable carbon monoxide sensor module620that may include a microprocessor carbon monoxide sensor with newer technology so as to allow for upgrade of the module disposed on the thermostat600. The replaceable carbon monoxide sensor module620also prompts the user to replace the replaceable carbon monoxide sensor module620upon determining that the carbon monoxide sensor is no longer reliable, such that the occupants are provided with reliable protection against the danger of carbon monoxide gas within the home.

It will be understood by those skilled in the art that the above thermostat and separate carbon monoxide sensor module located on the thermostat may be employed in various types of thermostats with any combination of the above disclosed features, without implementing the others. It will be understood that the thermostat and separate carbon monoxide sensor feature described above may be utilized in other forms of heating and cooling equipment, including remote temperature sensors. Accordingly, it should be understood that the disclosed embodiments, and variations thereof, may be employed in any type of thermostat or heating and cooling component.