CA2119194A1 - Smoke detector system for furnace - Google Patents
Smoke detector system for furnaceInfo
- Publication number
- CA2119194A1 CA2119194A1 CA002119194A CA2119194A CA2119194A1 CA 2119194 A1 CA2119194 A1 CA 2119194A1 CA 002119194 A CA002119194 A CA 002119194A CA 2119194 A CA2119194 A CA 2119194A CA 2119194 A1 CA2119194 A1 CA 2119194A1
- Authority
- CA
- Canada
- Prior art keywords
- smoke
- furnace
- housing
- air duct
- air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000779 smoke Substances 0.000 title claims description 151
- 238000001514 detection method Methods 0.000 claims description 43
- 238000003780 insertion Methods 0.000 claims description 5
- 230000037431 insertion Effects 0.000 claims description 5
- 238000005070 sampling Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- 239000002984 plastic foam Substances 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims 1
- 239000003990 capacitor Substances 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 239000004033 plastic Substances 0.000 description 4
- 229920003023 plastic Polymers 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 229920002457 flexible plastic Polymers 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
- G08B17/113—Constructional details
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fire-Detection Mechanisms (AREA)
- Fire Alarms (AREA)
Abstract
A combined smoke detection and furnace shut-off apparatus includes a smoke detector for sensing the presence of smoke in air. There are means for mounting this detector adjacent a return air duct for a furnace. A suitable conduit conducts a portion of air in the return air duct to the smoke detector. An alarm device is electrically connected to the detector and is operated thereby so that an alarm is sounded when smoke is sensed. The apparatus includes means for shutting down at least an ignition device and a blower in the furnace when a shut-down signal is generated by the smoke detector. Preferably the device includes a housing that is mounted on the exterior of the return air duct that contains the smoke detector. A perforated air intake pipe is connected to this housing and can be inserted into the return air duct through an opening. An air filter is mounted on this pipe.
Description
~, 2119194 This invention relates to smoke detectors and, in particular, smoke detectors adapted to control the operation of a furnace.
Smoke detectors for use in homes and offices are well known and the purpose of such detectors is to sound an alarm when a certain level of smoke is detected in the air surrounding the detector. A common form of smoke detector is the ionization type but other types are known. Often smoke detectors are battery operated so they need not be hooked up to electrical circuitry in the building and are able to operate independently. Generally said detectors are mounted on the ceiling of a room or hallway and it is often recommended that a detector be located on each floor of a building or residence.
United States patent No. 4,171,944 issued October 23, 1979 to J.B. Hirschm~nn teaches the use of a combined smoke detector and furnace shut-off device wherein the smoke detector is mounted to the wall or ceiling of the furnace room or possibly in one of the hot air ducts leading from the furnace. The purpose of this smoke detector is to sense the presence of smoke unnaturally expelled from the furnace into the furnace room or the hot air duct. When the smoke detector senses smoke, a signal is sent through a wire to an electrical relay connected to the ignition electrodes of the furnace, effectively shutting off the electrical supply to the ignition device. In addition, the smoke detector is able to generate ; a signal to operate a solenoid valve to shut-off the supply of fuel to the furnace.
There are several perceived difficulties with the smoke detection device taught in the aforementioned patent specification. One such difficulty is that if the smoke detector is mounted in the furnace room and not in any air duct, it will not detect any smoke that is entering into or passing through the furnace but which is not escaping from the furnace. Thus, the furnace may continue to operate even though there may be a fire in or smoke in other rooms in the house or building.
A second difficulty with the Hirschmann device is that, even if smoke is sensed by the device, the device will only shut-off the ignition mechanism for the furnace and perhaps also the supply of fuel to the furnace and this may permit the blower in the furnace to continue to operate. Experts in fire fighting note that a furnace fan or blower which continues to operate after a fire has started can only make matters worse by both distributing smoke to other rooms in the house through the duct system and by feeding the fire with the fresh air that it needs to sustain combustion and grow.
Even if the smoke detection mechanism is mounted in the hot air duct of the furnace rather than in the furnace room, the Hirschmann device may not operate satisfactorily. One reason for this is that the very hot air that enters a hot air duct from a furnace is too hot for most standard smoke detectors and would quickly cause the smoke detector to fail or to simply not operate. Another difficulty with the Hirschmann proposal is that any smoke returning to the furnace through the return air duct may not be passed into the hot air ~, .
duct in which the smoke detector is mounted and this would result in the smoke detector failing to operate even when there is smoke being circulated in or being generated in the house. Also, Hirschmann teaches no mechanism or system for drawing an adequate sample of air that is passing through a hot air duct to the smoke detector. For example, it is possible that smoke could pass through the hot air duct containing the smoke detector yet never come into contact with the smoke detector (for instance, the smoke might be blown past the smoke detector on the opposite side of the duct due to the arrangement or layout of the duct).
Recent U.S. patent No. 5,239,980, issued August 31, 1993 to F. E. Hilt et al., describes a forced air furnace control system for preventing the build up of dangerous concentrations of CO gas within a building. A CO sensor is mounted in the air exit plenum of the furnace and is connected in a circuit which produces an output signal when the concentration of CO
gas in the plenum reaches an unsafe level. A disable control signal is then triggered through the circuit for switching the furnace off.
U.S. patent No. 2,727,203 issued December 13, 1955 to Heat Timer Corporation describes an apparatus for detecting the presence of smoke in a chimney and subsequently shutting off a burner unit. This system employs an electronic control that becomes non-conductive with the presence of smoke to in turn de-energize a relay and initiate the operation of a - timer/burner/motor shut-off.
The present invention provides a unique smoke detection 211919~
.
apparatus designed for use in conjunction with a return air duct of a furnace. The smoke detector is able to detect the presence of smoke in an air sample drawn from the return air duct. If a certain level of smoke is detected, an alarm device connected to the smoke detector will sound an alarm and/or the apparatus will act to shut down the furnace and this may include both its ignition device and a blower or fan.
According to one aspect of the invention, a smoke detection apparatus comprises a housing adapted for mounting on the exterior of a return air duct for a furnace and smoke detection means for detecting the presence of smoke in the air present in the housing, the detection means being mounted in the housing. There are also means for drawing a small portion of air in the return air duct into the housing. An alarm device is electrically connected to the smoke detection mechanism and is controlled thereby so that the alarm device sounds an alarm when the smoke detection mechanism senses a predetermined level of smoke in the air present in the housing.
In the preferred apparatus disclosed herein there are also means for shutting down the furnace, including its ignition device and blower.
According to another`aspect of the invention, a combined smoke detection and furnace shut-off apparatus includes a smoke detector for sensing the presence of smoke in air and means for mounting this detector adjacent a return air duct for a furnace. There is also means for conducting a portion of air in the return air duct to the smoke detector. An alarm 21 I919~
device is electrically connected to the detector and is operated thereby so that the alarm device sounds an alarm when the smoke detector senses smoke in said portion of air and generates an alarm signal. There are also means for shutting down at least an ignition device and a blower of the furnace when a shut down signal is generated by the smoke detector.
This shutting down mechanism is electrically connected to the smoke detector.
According to a further aspect of the invention, a furnace shut-off apparatus includes a smoke detector device for sensing the presence of smoke in an air sample taken from air in a return air duct for a furnace and a mechanism for shutting down the furnace when the smoke detector device senses a predetermined level of smoke in the air of the return air duct. The shutting down mechanism is electrically connected to the smoke detector device.
Further features and advantages will become apparent from the following detailed description taken in conjunction with the drawings.
In the drawings, Figure 1 is a perspective view of the top portion of a typical furnace equipped with a smoke detection apparatus constructed in accordance with the invention;
Figure 2 is a cross-sectional elevation taken through the ~ 25 axial centre of an air intake pipe of the smoke detection - apparatus;
Figure 3 is a detail view in elevation, and partly in cross-section, showing the mechanism for returning sampled air to a hot air duct of the furnace;
Figure 4 is a detail view showing a block connector that can be used to connect the apparatus of the invention to a furnace control box; and Figure 5 is an electrical circuit diagram illustrating the preferred form of electrical circuit for a combined smoke detection and furnace shut-off apparatus constructed in accordance with the invention.
Shown in Figure 1 is a standard forced furnace 10 which may be fuelled typically by natural gas or fuel oil. As is well know, these furnaces are equipped with a suitable ignition device (not shown) and a blower or fan for circulating air through the furnace. As illustrated, incoming ; air enters the top of the furnace through a return air duct- 15 12. It will be appreciated that this return air duct is connected to various rooms or hallways in the house or building by ductwork so as to enable the air in these rooms and hallways to return to the furnace where it can be reheated. The returned air passes through a suitable heat ; 20 exchanger in the furnace and then the hot air is delivered to the rooms in the house or building by means of one or more hot air ducts 14.
Such furnaces are normally electrically operated and are provided with power through a main power supply line indicated at 16. This line is connected to a furnace control box 18 which is typically mountèd on one side of the furnace or inside the exterior walls of the furnace. It will be understood that this control box provides electrical power to all of the electrically operated components of the furnace including an ignition device, a fuel pump (if required) and a blower or fan.
A preferred form of smoke detection apparatus constructed in accordance with the invention is indicated generally at 20.
It includes a box-like housing 22 which is adapted for mounting on the exterior of the return air duct 12. As shown in Figures 1 and 2, the housing can be provided with top and bottom connecting flanges 24 and 26 and sheet metal screws 28 can be used to connect these flanges to the side of the duct.
As shown, the housing includes a top wall 30, an outer wall 32, a bottom 34 and two smaller, vertical sidewalls 36. The housing is equipped with a further wall 38 which faces the adjacent duct wall and which has a circular opening at 40.
15Mounted inside of the housing is a suitable smoke sensor or smoke detector 42 which senses the presence of smoke in air present in the housing. This smoke detector 42 can be of standard, known construction and therefore a detailed description of the detector herein is deemed unnecessary. For example, it can be a standard ionization type detector or a photoelectric smoke detector. This detector can be provided with suitable electrical power through an electrical cord 44 that extends out of the housing. If, for example, the ; detector operates with 12 volt power, a standard step-down transformer 46 can be connected to the cord 44. This transformer has plugs at 48 for plugging the transformer into a standard wall socket capable of providing 120 volts.
The apparatus 20 is equipped with means for drawing a small portion of air from the return air duct into the housing 22. The preferred drawing mechanism, as illustrated, is a perforated air intake pipe 50 having a closed end 52 and an open end at the aforementioned opening 4D in the housing.
This suction tube is preferably made of a suitable rigid plastic but it could also be made of a metal such as steel or tin. This pipe is adapted for insertion into the return air duct and generally would have a length sufficient to extend substantially across the width of the return air duct. In one preferred embodiment, this pipe is about 12 inches long and has an external diameter of about 2 inches. Preferably, in order that the pipe will have an even draw across the duct, the pipe is provided with either more openings S4 at its end closer to the smoke detector housing than at its opposite end or it is provided with larger openings at the end closer to the housing. It will be understood that the pipe opens into a sample chamber 56 formed by the housing.
Preferably there is mounted on the pipe 50 an air filter 58 which, in one preferred embodiment, is a broken cell plastic foam filter in the form of a sleeve. The preferred illustrated filter extends around and along the length of the pipe 50 and thus the filter also has a length sufficient to extend substantially across the width of the duct. In one preferred embodiment the filter sleeve has an internal diameter of 2 inches and an outer diameter of 3 inches. It will be understood that there is cut or otherwise formed in the air duct wall 60 a circular opening 62 having a diameter large enough to permit insertion of both the pipe 50 and its
Smoke detectors for use in homes and offices are well known and the purpose of such detectors is to sound an alarm when a certain level of smoke is detected in the air surrounding the detector. A common form of smoke detector is the ionization type but other types are known. Often smoke detectors are battery operated so they need not be hooked up to electrical circuitry in the building and are able to operate independently. Generally said detectors are mounted on the ceiling of a room or hallway and it is often recommended that a detector be located on each floor of a building or residence.
United States patent No. 4,171,944 issued October 23, 1979 to J.B. Hirschm~nn teaches the use of a combined smoke detector and furnace shut-off device wherein the smoke detector is mounted to the wall or ceiling of the furnace room or possibly in one of the hot air ducts leading from the furnace. The purpose of this smoke detector is to sense the presence of smoke unnaturally expelled from the furnace into the furnace room or the hot air duct. When the smoke detector senses smoke, a signal is sent through a wire to an electrical relay connected to the ignition electrodes of the furnace, effectively shutting off the electrical supply to the ignition device. In addition, the smoke detector is able to generate ; a signal to operate a solenoid valve to shut-off the supply of fuel to the furnace.
There are several perceived difficulties with the smoke detection device taught in the aforementioned patent specification. One such difficulty is that if the smoke detector is mounted in the furnace room and not in any air duct, it will not detect any smoke that is entering into or passing through the furnace but which is not escaping from the furnace. Thus, the furnace may continue to operate even though there may be a fire in or smoke in other rooms in the house or building.
A second difficulty with the Hirschmann device is that, even if smoke is sensed by the device, the device will only shut-off the ignition mechanism for the furnace and perhaps also the supply of fuel to the furnace and this may permit the blower in the furnace to continue to operate. Experts in fire fighting note that a furnace fan or blower which continues to operate after a fire has started can only make matters worse by both distributing smoke to other rooms in the house through the duct system and by feeding the fire with the fresh air that it needs to sustain combustion and grow.
Even if the smoke detection mechanism is mounted in the hot air duct of the furnace rather than in the furnace room, the Hirschmann device may not operate satisfactorily. One reason for this is that the very hot air that enters a hot air duct from a furnace is too hot for most standard smoke detectors and would quickly cause the smoke detector to fail or to simply not operate. Another difficulty with the Hirschmann proposal is that any smoke returning to the furnace through the return air duct may not be passed into the hot air ~, .
duct in which the smoke detector is mounted and this would result in the smoke detector failing to operate even when there is smoke being circulated in or being generated in the house. Also, Hirschmann teaches no mechanism or system for drawing an adequate sample of air that is passing through a hot air duct to the smoke detector. For example, it is possible that smoke could pass through the hot air duct containing the smoke detector yet never come into contact with the smoke detector (for instance, the smoke might be blown past the smoke detector on the opposite side of the duct due to the arrangement or layout of the duct).
Recent U.S. patent No. 5,239,980, issued August 31, 1993 to F. E. Hilt et al., describes a forced air furnace control system for preventing the build up of dangerous concentrations of CO gas within a building. A CO sensor is mounted in the air exit plenum of the furnace and is connected in a circuit which produces an output signal when the concentration of CO
gas in the plenum reaches an unsafe level. A disable control signal is then triggered through the circuit for switching the furnace off.
U.S. patent No. 2,727,203 issued December 13, 1955 to Heat Timer Corporation describes an apparatus for detecting the presence of smoke in a chimney and subsequently shutting off a burner unit. This system employs an electronic control that becomes non-conductive with the presence of smoke to in turn de-energize a relay and initiate the operation of a - timer/burner/motor shut-off.
The present invention provides a unique smoke detection 211919~
.
apparatus designed for use in conjunction with a return air duct of a furnace. The smoke detector is able to detect the presence of smoke in an air sample drawn from the return air duct. If a certain level of smoke is detected, an alarm device connected to the smoke detector will sound an alarm and/or the apparatus will act to shut down the furnace and this may include both its ignition device and a blower or fan.
According to one aspect of the invention, a smoke detection apparatus comprises a housing adapted for mounting on the exterior of a return air duct for a furnace and smoke detection means for detecting the presence of smoke in the air present in the housing, the detection means being mounted in the housing. There are also means for drawing a small portion of air in the return air duct into the housing. An alarm device is electrically connected to the smoke detection mechanism and is controlled thereby so that the alarm device sounds an alarm when the smoke detection mechanism senses a predetermined level of smoke in the air present in the housing.
In the preferred apparatus disclosed herein there are also means for shutting down the furnace, including its ignition device and blower.
According to another`aspect of the invention, a combined smoke detection and furnace shut-off apparatus includes a smoke detector for sensing the presence of smoke in air and means for mounting this detector adjacent a return air duct for a furnace. There is also means for conducting a portion of air in the return air duct to the smoke detector. An alarm 21 I919~
device is electrically connected to the detector and is operated thereby so that the alarm device sounds an alarm when the smoke detector senses smoke in said portion of air and generates an alarm signal. There are also means for shutting down at least an ignition device and a blower of the furnace when a shut down signal is generated by the smoke detector.
This shutting down mechanism is electrically connected to the smoke detector.
According to a further aspect of the invention, a furnace shut-off apparatus includes a smoke detector device for sensing the presence of smoke in an air sample taken from air in a return air duct for a furnace and a mechanism for shutting down the furnace when the smoke detector device senses a predetermined level of smoke in the air of the return air duct. The shutting down mechanism is electrically connected to the smoke detector device.
Further features and advantages will become apparent from the following detailed description taken in conjunction with the drawings.
In the drawings, Figure 1 is a perspective view of the top portion of a typical furnace equipped with a smoke detection apparatus constructed in accordance with the invention;
Figure 2 is a cross-sectional elevation taken through the ~ 25 axial centre of an air intake pipe of the smoke detection - apparatus;
Figure 3 is a detail view in elevation, and partly in cross-section, showing the mechanism for returning sampled air to a hot air duct of the furnace;
Figure 4 is a detail view showing a block connector that can be used to connect the apparatus of the invention to a furnace control box; and Figure 5 is an electrical circuit diagram illustrating the preferred form of electrical circuit for a combined smoke detection and furnace shut-off apparatus constructed in accordance with the invention.
Shown in Figure 1 is a standard forced furnace 10 which may be fuelled typically by natural gas or fuel oil. As is well know, these furnaces are equipped with a suitable ignition device (not shown) and a blower or fan for circulating air through the furnace. As illustrated, incoming ; air enters the top of the furnace through a return air duct- 15 12. It will be appreciated that this return air duct is connected to various rooms or hallways in the house or building by ductwork so as to enable the air in these rooms and hallways to return to the furnace where it can be reheated. The returned air passes through a suitable heat ; 20 exchanger in the furnace and then the hot air is delivered to the rooms in the house or building by means of one or more hot air ducts 14.
Such furnaces are normally electrically operated and are provided with power through a main power supply line indicated at 16. This line is connected to a furnace control box 18 which is typically mountèd on one side of the furnace or inside the exterior walls of the furnace. It will be understood that this control box provides electrical power to all of the electrically operated components of the furnace including an ignition device, a fuel pump (if required) and a blower or fan.
A preferred form of smoke detection apparatus constructed in accordance with the invention is indicated generally at 20.
It includes a box-like housing 22 which is adapted for mounting on the exterior of the return air duct 12. As shown in Figures 1 and 2, the housing can be provided with top and bottom connecting flanges 24 and 26 and sheet metal screws 28 can be used to connect these flanges to the side of the duct.
As shown, the housing includes a top wall 30, an outer wall 32, a bottom 34 and two smaller, vertical sidewalls 36. The housing is equipped with a further wall 38 which faces the adjacent duct wall and which has a circular opening at 40.
15Mounted inside of the housing is a suitable smoke sensor or smoke detector 42 which senses the presence of smoke in air present in the housing. This smoke detector 42 can be of standard, known construction and therefore a detailed description of the detector herein is deemed unnecessary. For example, it can be a standard ionization type detector or a photoelectric smoke detector. This detector can be provided with suitable electrical power through an electrical cord 44 that extends out of the housing. If, for example, the ; detector operates with 12 volt power, a standard step-down transformer 46 can be connected to the cord 44. This transformer has plugs at 48 for plugging the transformer into a standard wall socket capable of providing 120 volts.
The apparatus 20 is equipped with means for drawing a small portion of air from the return air duct into the housing 22. The preferred drawing mechanism, as illustrated, is a perforated air intake pipe 50 having a closed end 52 and an open end at the aforementioned opening 4D in the housing.
This suction tube is preferably made of a suitable rigid plastic but it could also be made of a metal such as steel or tin. This pipe is adapted for insertion into the return air duct and generally would have a length sufficient to extend substantially across the width of the return air duct. In one preferred embodiment, this pipe is about 12 inches long and has an external diameter of about 2 inches. Preferably, in order that the pipe will have an even draw across the duct, the pipe is provided with either more openings S4 at its end closer to the smoke detector housing than at its opposite end or it is provided with larger openings at the end closer to the housing. It will be understood that the pipe opens into a sample chamber 56 formed by the housing.
Preferably there is mounted on the pipe 50 an air filter 58 which, in one preferred embodiment, is a broken cell plastic foam filter in the form of a sleeve. The preferred illustrated filter extends around and along the length of the pipe 50 and thus the filter also has a length sufficient to extend substantially across the width of the duct. In one preferred embodiment the filter sleeve has an internal diameter of 2 inches and an outer diameter of 3 inches. It will be understood that there is cut or otherwise formed in the air duct wall 60 a circular opening 62 having a diameter large enough to permit insertion of both the pipe 50 and its
2~1919 ~, surrounding air filter 58. It will be understood that the purpose of the filter 58 is to remove large particles from the sample of air being drawn into the housing 22. This will help ensure that such particles do not interfere with the operation of reduce the life of the smoke detector 42.
It is highly advantageous to have an air sampling pipe such as the perforated pipe 50 that extends across the width of the duct. This helps to ensure that any smoke passing through the return air duct will be drawn into the pipe and sensed by the smoke sensor 42. If there was only a simple opening 62 cut in the return air duct for sampling purposes, it is quite possible that smoke could pass down through the return air duct, for example on the side opposite the opening 62, and not be drawn into the housing 22. Thus, the use of the sampling pipe 50 helps to ensure the reliability of the smoke detection apparatus.
Also part of the drawing mechanism is a conduit or pipe 66 which is connected to the housing 22 and is adapted for connection to an adjacent hot air duct such as illustrated duct 14. It will be appreciated that there is a low pressure region created at the outlet 68 of the pipe 66 by the relatively fast moving hot air in the duct 14, which air is being blown through the duct by a blower or fan in the furnace. The direction of movement of this hot air is indicated by the arrow H in Figures 1 and 3. It is because the air in the housing 22 is drawn out of the housing through the pipe 66 that air is drawn into the housing via the sampling pipe 50. Instead of using the pipe 66 and the hot 211919~
air duct, it would also be possible to force air out of the housing 22 through an opening therein by means, for example, of a small fan or blower. However, this solution could be more expensive to construct and to maintain and operate over a long period of time. Moreover, if a fan is used, in order that the fan would not operate unnecessarily, for example, when the furnace itself is not operating, it may be desirable to provide an electrical control mechanism whereby the fan for the smoke detection apparatus would only operate when the blower or fan in the furnace is operating.
In a preferred embodiment, a pivoting damper is provided at the intake opening of the housing 22. This damper can be of standard design and is very simple in its construction. It is manually adjusted by the installer of the present smoke detection apparatus. It is mounted on the side of the housing 22 with its pivot pin projecting through the side of the housing where it can be turned to make an adjustment. The damper is normally set to permit an air flow of between 150 and 200 cu. ft. per minute. The liquid filled nonometer of standard construction and mounted on the housing can be used to set this air flow, which operation is done when the furnace is turned on and running.
; In one preferred embodiment of the invention, the pipe 66 is a one inch flexible plastic pipe that is attached to the hot air duct by means of a plastic flange connector 70 that is connected to the wall of the duct by means of sheet metal screws 72. In the illustrated preferred embodiment, the flange connector includes a plastic air deflector 74 that acts 211919~
to deflect the returning air from the pipe 66 in the direction of the hot air passing through the duct. Thus, in the illustrated embodiment of Figures 1 and 3, the deflector 74 is arranged to deflect the sampled air upwardly.
The preferred smoke detection apparatus of the invention includes an alarm device 76 that is electrically connected to the smoke detector or smoke sensor 42 and controlled thereby so that the alarm device sounds an alarm when the smoke detector senses a predetermined level of smoke in the air present in the housing. Except for the manner in which the alarm or buzzer is mounted, the alarm device can be of standard construction and similar to those used in previously known smoke detectors. However, in the preferred embodiment of the invention, the alarm device 76 is adapted for mounting on a hot air duct such as the duct 14. In this way, the sound made by the alarm will readily travel through the hollow hot air duct or ducts so that it can be heard at various locations and on different levels of the housing or dwelling. Although it is possible to mount the alarm device 76 right in the hot air duct, in the illustrated embodiment it is hard mounted to the plastic flange connector 70 on the outside of the hot air duct. Even in this outside position, testing has shown that the sound caused by the alarm readily travels through the hot air duct to distance locations in the house or building. The alarm device 76 is connected to the smoke detector by an electrical wire 78 of sufficient length to reach between the housing and the location of the buzzer on the hot air duct.
It will be understood that the alarm device is actuated and ; - 13 sounds an alarm when the smoke detector or sensor 42 senses smoke in the sampled air and generates an alarm signal.
In the preferred combined smoke detection and furnace shut-off apparatus of the invention there is also means for shutting down the furnace 10, including an ignition device and a blower thereof. This shutting down mechanism indicated generally at 80 is connected to the smoke sensor 42 and controlled thereby. The shutting down mechanism operates to shut down the furnace when the smoke detector senses a predetermined level of smoke in the air present in the ; housing. Generally speaking, this would be the same level of - smoke that sets off the alarm device 76. The preferred shutting down mechanism, when activated, breaks a power line L1 which is part of supply line 16, providing electrical power to the furnace. The shutting down mechanism includes an electrical lead 82 extending from the housing 22 and the smoke sensor therein to a line connector 84 illustrated in Figure 4.
In a typical furnace installation having a furnace control box ; 18, the apparatus of the invention is connected into this control box by first disconnecting the main power lead L1 from the control panel in the box. It is then simply necessary to connect the connector block 84 by pushing in the plug or jack 86 that extends from one side of the block. The plug or jack 86 is connected at the location where L1 was connected. The line L1 is then inserted into and connected to the block 84.
The lead or line 82 is connected to a suitable latching relay 46 located in the housing 22, which relay is illustrated schematically in the circuit diagram of Figure 5.
~, - 2119191 Although the illustrated embodiment of the smoke detection apparatus 20 is provided with electrical power from a wall outlet, it will be understood that the apparatus could also be provided with power from one or more batteries in the same manner as known smoke detectors.
The two electrical leads extending between the connector 84 and the junction box 90 in the housing 22 can comprise BX
cable. By means of this cable, the 120 volt power supply coming in through line 16 is rerouted to an inlet connection of the junction box. The second lead 82 connects a power outlet side of the junction box to the control box 18, thereby normally providing electrical power to the furnace components, including its blower and ignition device.
In the electrical circuit diagram of Figure 5 the wall socket power pack that provides power to the smoke detector 42 includes a four-way bridge 102 to rectify the alternating current and provide the DC power supply. Connected to this bridge is a resistor 103, which can be a lK resistor, which acts to limit current to the LED. Connected to the resistor is an LED 105. Also connected to the resistor is a capacitor 98 to smooth out the DC current. Connected in the line from the bridge 102 to the smoke detector is a 1/2W resistor 100 to current limit the voltage. Connected between power line 107 and the smoke detector 42 is a zenor diode 96 which acts as a voltage regulator providing 9 volts. There are two identical diodes indicated at 109 which act to rectify the square wave signal from the smoke detector in order to charge a capacitor 94. The purpose of the capacitor 94 is to provide a delay so i~ .
that two beeps from the smoke detector are required to shut down the furnace. As is usual, the smoke detector 42 is provided with a test switch indicated at 92, which switch can be closed manually in order to test the unit.
Indicated at 46 is a latching relay, which relay is located in the housing 22 containing the smoke detector. This latching relay is activated once the smoke detector has detected smoke and has set off an alarm and will continue to operate to keep the furnace off even if the electrical power fails. An electrical line 108 connects this latching relay to the smoke detector and the capacitor 94. The relay has two contacts indicated at 112 and 114. These contacts are shown in the reset condition and in the reset condition power is supplied to a second relay indicated at 118. This second relay must be energized in order to allow the furnace to operate.
However, in the set condition the upper contact 114 will supply 12 volt power to the remote beeper or alarm device 76 while the lower contact 112 supplies 12 volt power to a LED
diode 115. Also, in the set condition the upper contact disconnects power from the second relay 118. The second relay has a single contact 120 and this relay is connected to a terminal strip with two connecting screws indicated at 121.
It is the screws 121 which are connected to the furnace wires including electrical lead 82 indicated in Figure 1. Also shown in Figure 5 is a lK resistor 116. The resistor 116 which is connected to ground is a current limiting resistor for the alarm LED 115, this LED comprising a simple red light - 211919~
indicating that the alarm has been triggered and is shutting down the furnace.
In one preferred embodiment the zenor diode 96 is type IN5346B and the two diodes 109 are type IN4001.
It will be understood that the reset button at 104 is pushed to close the switch when smoke has been cleared from the system and one wishes the furnace now to operate.
It will be appreciated that various modifications and changes can be made to the described combined smoke detection and furnace shut-off apparatus without departing from the spirit and scope of this invention. Accordingly, all such modifications and changes as fall within the scope of the appended claims are intended to be part of this invention.
It is highly advantageous to have an air sampling pipe such as the perforated pipe 50 that extends across the width of the duct. This helps to ensure that any smoke passing through the return air duct will be drawn into the pipe and sensed by the smoke sensor 42. If there was only a simple opening 62 cut in the return air duct for sampling purposes, it is quite possible that smoke could pass down through the return air duct, for example on the side opposite the opening 62, and not be drawn into the housing 22. Thus, the use of the sampling pipe 50 helps to ensure the reliability of the smoke detection apparatus.
Also part of the drawing mechanism is a conduit or pipe 66 which is connected to the housing 22 and is adapted for connection to an adjacent hot air duct such as illustrated duct 14. It will be appreciated that there is a low pressure region created at the outlet 68 of the pipe 66 by the relatively fast moving hot air in the duct 14, which air is being blown through the duct by a blower or fan in the furnace. The direction of movement of this hot air is indicated by the arrow H in Figures 1 and 3. It is because the air in the housing 22 is drawn out of the housing through the pipe 66 that air is drawn into the housing via the sampling pipe 50. Instead of using the pipe 66 and the hot 211919~
air duct, it would also be possible to force air out of the housing 22 through an opening therein by means, for example, of a small fan or blower. However, this solution could be more expensive to construct and to maintain and operate over a long period of time. Moreover, if a fan is used, in order that the fan would not operate unnecessarily, for example, when the furnace itself is not operating, it may be desirable to provide an electrical control mechanism whereby the fan for the smoke detection apparatus would only operate when the blower or fan in the furnace is operating.
In a preferred embodiment, a pivoting damper is provided at the intake opening of the housing 22. This damper can be of standard design and is very simple in its construction. It is manually adjusted by the installer of the present smoke detection apparatus. It is mounted on the side of the housing 22 with its pivot pin projecting through the side of the housing where it can be turned to make an adjustment. The damper is normally set to permit an air flow of between 150 and 200 cu. ft. per minute. The liquid filled nonometer of standard construction and mounted on the housing can be used to set this air flow, which operation is done when the furnace is turned on and running.
; In one preferred embodiment of the invention, the pipe 66 is a one inch flexible plastic pipe that is attached to the hot air duct by means of a plastic flange connector 70 that is connected to the wall of the duct by means of sheet metal screws 72. In the illustrated preferred embodiment, the flange connector includes a plastic air deflector 74 that acts 211919~
to deflect the returning air from the pipe 66 in the direction of the hot air passing through the duct. Thus, in the illustrated embodiment of Figures 1 and 3, the deflector 74 is arranged to deflect the sampled air upwardly.
The preferred smoke detection apparatus of the invention includes an alarm device 76 that is electrically connected to the smoke detector or smoke sensor 42 and controlled thereby so that the alarm device sounds an alarm when the smoke detector senses a predetermined level of smoke in the air present in the housing. Except for the manner in which the alarm or buzzer is mounted, the alarm device can be of standard construction and similar to those used in previously known smoke detectors. However, in the preferred embodiment of the invention, the alarm device 76 is adapted for mounting on a hot air duct such as the duct 14. In this way, the sound made by the alarm will readily travel through the hollow hot air duct or ducts so that it can be heard at various locations and on different levels of the housing or dwelling. Although it is possible to mount the alarm device 76 right in the hot air duct, in the illustrated embodiment it is hard mounted to the plastic flange connector 70 on the outside of the hot air duct. Even in this outside position, testing has shown that the sound caused by the alarm readily travels through the hot air duct to distance locations in the house or building. The alarm device 76 is connected to the smoke detector by an electrical wire 78 of sufficient length to reach between the housing and the location of the buzzer on the hot air duct.
It will be understood that the alarm device is actuated and ; - 13 sounds an alarm when the smoke detector or sensor 42 senses smoke in the sampled air and generates an alarm signal.
In the preferred combined smoke detection and furnace shut-off apparatus of the invention there is also means for shutting down the furnace 10, including an ignition device and a blower thereof. This shutting down mechanism indicated generally at 80 is connected to the smoke sensor 42 and controlled thereby. The shutting down mechanism operates to shut down the furnace when the smoke detector senses a predetermined level of smoke in the air present in the ; housing. Generally speaking, this would be the same level of - smoke that sets off the alarm device 76. The preferred shutting down mechanism, when activated, breaks a power line L1 which is part of supply line 16, providing electrical power to the furnace. The shutting down mechanism includes an electrical lead 82 extending from the housing 22 and the smoke sensor therein to a line connector 84 illustrated in Figure 4.
In a typical furnace installation having a furnace control box ; 18, the apparatus of the invention is connected into this control box by first disconnecting the main power lead L1 from the control panel in the box. It is then simply necessary to connect the connector block 84 by pushing in the plug or jack 86 that extends from one side of the block. The plug or jack 86 is connected at the location where L1 was connected. The line L1 is then inserted into and connected to the block 84.
The lead or line 82 is connected to a suitable latching relay 46 located in the housing 22, which relay is illustrated schematically in the circuit diagram of Figure 5.
~, - 2119191 Although the illustrated embodiment of the smoke detection apparatus 20 is provided with electrical power from a wall outlet, it will be understood that the apparatus could also be provided with power from one or more batteries in the same manner as known smoke detectors.
The two electrical leads extending between the connector 84 and the junction box 90 in the housing 22 can comprise BX
cable. By means of this cable, the 120 volt power supply coming in through line 16 is rerouted to an inlet connection of the junction box. The second lead 82 connects a power outlet side of the junction box to the control box 18, thereby normally providing electrical power to the furnace components, including its blower and ignition device.
In the electrical circuit diagram of Figure 5 the wall socket power pack that provides power to the smoke detector 42 includes a four-way bridge 102 to rectify the alternating current and provide the DC power supply. Connected to this bridge is a resistor 103, which can be a lK resistor, which acts to limit current to the LED. Connected to the resistor is an LED 105. Also connected to the resistor is a capacitor 98 to smooth out the DC current. Connected in the line from the bridge 102 to the smoke detector is a 1/2W resistor 100 to current limit the voltage. Connected between power line 107 and the smoke detector 42 is a zenor diode 96 which acts as a voltage regulator providing 9 volts. There are two identical diodes indicated at 109 which act to rectify the square wave signal from the smoke detector in order to charge a capacitor 94. The purpose of the capacitor 94 is to provide a delay so i~ .
that two beeps from the smoke detector are required to shut down the furnace. As is usual, the smoke detector 42 is provided with a test switch indicated at 92, which switch can be closed manually in order to test the unit.
Indicated at 46 is a latching relay, which relay is located in the housing 22 containing the smoke detector. This latching relay is activated once the smoke detector has detected smoke and has set off an alarm and will continue to operate to keep the furnace off even if the electrical power fails. An electrical line 108 connects this latching relay to the smoke detector and the capacitor 94. The relay has two contacts indicated at 112 and 114. These contacts are shown in the reset condition and in the reset condition power is supplied to a second relay indicated at 118. This second relay must be energized in order to allow the furnace to operate.
However, in the set condition the upper contact 114 will supply 12 volt power to the remote beeper or alarm device 76 while the lower contact 112 supplies 12 volt power to a LED
diode 115. Also, in the set condition the upper contact disconnects power from the second relay 118. The second relay has a single contact 120 and this relay is connected to a terminal strip with two connecting screws indicated at 121.
It is the screws 121 which are connected to the furnace wires including electrical lead 82 indicated in Figure 1. Also shown in Figure 5 is a lK resistor 116. The resistor 116 which is connected to ground is a current limiting resistor for the alarm LED 115, this LED comprising a simple red light - 211919~
indicating that the alarm has been triggered and is shutting down the furnace.
In one preferred embodiment the zenor diode 96 is type IN5346B and the two diodes 109 are type IN4001.
It will be understood that the reset button at 104 is pushed to close the switch when smoke has been cleared from the system and one wishes the furnace now to operate.
It will be appreciated that various modifications and changes can be made to the described combined smoke detection and furnace shut-off apparatus without departing from the spirit and scope of this invention. Accordingly, all such modifications and changes as fall within the scope of the appended claims are intended to be part of this invention.
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A smoke detection apparatus comprising:
a housing adapted for mounting on the exterior of a return air duct for a furnace;
smoke detection means for detecting the presence of smoke in air present in said housing, said detection means being mounted in said housing;
means for drawing a small portion of air in said return air duct into said housing;
an alarm device electrically connected to said smoke detection means and controlled thereby so that said alarm device sounds an alarm when said smoke detection means senses a predetermined level of smoke in the air present in said housing.
a housing adapted for mounting on the exterior of a return air duct for a furnace;
smoke detection means for detecting the presence of smoke in air present in said housing, said detection means being mounted in said housing;
means for drawing a small portion of air in said return air duct into said housing;
an alarm device electrically connected to said smoke detection means and controlled thereby so that said alarm device sounds an alarm when said smoke detection means senses a predetermined level of smoke in the air present in said housing.
2. A smoke detection apparatus according to claim 1 including means for shutting down said furnace including an ignition device and blower of the furnace, said shutting down means being connected to said smoke detection means and controlled thereby so that said shutting down means operates to shut down the furnace when said smoke detection means senses said predetermined level of smoke in the air present in said housing.
3. A smoke detection apparatus according to claim 1 wherein said drawing means includes a perforated air intake pipe connected to said housing and adapted for insertion into said return air duct and an air filter mounted in or on said pipe.
4. A smoke detection apparatus according to claim 3 wherein said drawing means includes conduit means connected to said housing and adapted for connection to a hot air duct, said conduit means in use acting to draw sampled air from said housing and into said hot air duct.
5. A smoke detection apparatus according to any one of claims 1 to 4 wherein said alarm device is adapted for mounting on a hot air duct extending from said furnace, said alarm device being connected to said smoke detection means by an electrical wire of sufficient length to reach the hot air duct.
6. A smoke detector apparatus according to claim 3 or 4 wherein said air intake pipe and filter have a length sufficient to extend substantially across the width of said return air duct when they are mounted therein.
7. A smoke detection apparatus according to claim 3 or 4 wherein said air filter is a plastic foam filter in the form of a sleeve that extends around and along the length of said air intake pipe.
8. A smoke detection apparatus according to any one of claims 1 to 4 wherein said smoke detection means comprises an ionization type smoke detector.
9. A smoke detector apparatus according to any one of claims 1 to 4 including a step-down transformer means electrically connected to said smoke detection means for providing low voltage electrical power to said smoke detection means, said transformer means including an electrical plug for connecting said transformer to a 120 volt electrical circuit.
10. A smoke detection apparatus according to claim 2 wherein said shutting down means, when activated, breaks a power line providing electrical power to said furnace, said shutting down means including an electrical lead extending from said housing to a line connector.
11. A combined smoke detector and furnace shut-off apparatus comprising:
a smoke detector for sensing the presence of smoke in air;
means for mounting said detector adjacent a return air duct for a furnace;
means for conducting a portion of air in said return air duct to said smoke detector;
an alarm device electrically connected to said smoke detector and operated thereby so that said alarm device sounds an alarm when said smoke detector senses smoke in said portion of air and generates an alarm signal; and means for shutting down at least an ignition device and a blower in said furnace when a shut down signal is generated by said smoke detector, said shutting down means being electrically connected to said smoke detector.
a smoke detector for sensing the presence of smoke in air;
means for mounting said detector adjacent a return air duct for a furnace;
means for conducting a portion of air in said return air duct to said smoke detector;
an alarm device electrically connected to said smoke detector and operated thereby so that said alarm device sounds an alarm when said smoke detector senses smoke in said portion of air and generates an alarm signal; and means for shutting down at least an ignition device and a blower in said furnace when a shut down signal is generated by said smoke detector, said shutting down means being electrically connected to said smoke detector.
12. A combined smoke detection and furnace shut-off apparatus according to claim 11 wherein said conducting means is an air intake pipe adapted for insertion into said return air duct so as to extend transversely across said return air duct, said pipe being capable of sampling air across the width of the duct.
13. A combined smoke detection and furnace shut-off apparatus according to claim 12 including a large particle filter mounted in or on said air intake pipe.
14. A combined smoke detection and furnace shut-off apparatus according to any one of claims 11 to 13 including an air conduit for conducting sampled air from said smoke detector to a hot air duct connected to said furnace.
15. A combined smoke detection and furnace shut-off apparatus according to any one of claims 11 to 13 wherein said smoke detector includes a housing therefor and said conducting means is attached to said housing and extends from one side thereof.
16. A furnace shut-off apparatus comprising:
a smoke detector device for sensing the presence of smoke in an air sample taken from air in a return air duct for a furnace; and means for shutting down said furnace when said smoke detector device senses a predetermined level of smoke in the air of said return air duct, said shutting down means being electrically connected to said smoke detector device.
a smoke detector device for sensing the presence of smoke in an air sample taken from air in a return air duct for a furnace; and means for shutting down said furnace when said smoke detector device senses a predetermined level of smoke in the air of said return air duct, said shutting down means being electrically connected to said smoke detector device.
17. A furnace shut-off apparatus according to claim 16 wherein said smoke detector device includes a housing adapted for mounting outside said return air duct, means for drawing said air sample from said return air duct to the interior of said housing, and smoke detection means mounted in said housing.
18. A furnace shut-off apparatus according to claim 17 wherein said drawing means includes an air intake pipe adapted for insertion into said return air duct and an air conduit connected at one end to said housing and connectible at its opposite end to a hot air duct connected to said furnace.
19. A furnace shut-off apparatus according to any one of claims 16 to 18 including filtration means for removing any large particles from said air sample.
20. A furnace shut-off apparatus according to any one of claims 16 to 18 wherein said shutting down means, when activated, breaks off a power line providing electrical power to said furnace, said shutting down means including an electrical line extending from the smoke detector device to a line connector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002119194A CA2119194A1 (en) | 1994-03-16 | 1994-03-16 | Smoke detector system for furnace |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002119194A CA2119194A1 (en) | 1994-03-16 | 1994-03-16 | Smoke detector system for furnace |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2119194A1 true CA2119194A1 (en) | 1995-09-17 |
Family
ID=4153180
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002119194A Abandoned CA2119194A1 (en) | 1994-03-16 | 1994-03-16 | Smoke detector system for furnace |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2119194A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002009057A1 (en) * | 2000-07-25 | 2002-01-31 | Pyrone As | Device for monitoring the operation of equipment |
| US9905122B2 (en) | 2013-10-07 | 2018-02-27 | Google Llc | Smart-home control system providing HVAC system dependent responses to hazard detection events |
| DE202017101367U1 (en) * | 2017-03-10 | 2018-06-13 | Werner Wildeboer | duct smoke |
| CN113706812A (en) * | 2021-08-16 | 2021-11-26 | 杭州基础创新科技有限公司 | Monitoring device for realizing early warning of electrical fire |
-
1994
- 1994-03-16 CA CA002119194A patent/CA2119194A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002009057A1 (en) * | 2000-07-25 | 2002-01-31 | Pyrone As | Device for monitoring the operation of equipment |
| US9905122B2 (en) | 2013-10-07 | 2018-02-27 | Google Llc | Smart-home control system providing HVAC system dependent responses to hazard detection events |
| DE202017101367U1 (en) * | 2017-03-10 | 2018-06-13 | Werner Wildeboer | duct smoke |
| CN113706812A (en) * | 2021-08-16 | 2021-11-26 | 杭州基础创新科技有限公司 | Monitoring device for realizing early warning of electrical fire |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |