US20020134320A1 - Ignition inhibiting gas water heater and controller - Google Patents
Ignition inhibiting gas water heater and controller Download PDFInfo
- Publication number
- US20020134320A1 US20020134320A1 US10/145,312 US14531202A US2002134320A1 US 20020134320 A1 US20020134320 A1 US 20020134320A1 US 14531202 A US14531202 A US 14531202A US 2002134320 A1 US2002134320 A1 US 2002134320A1
- Authority
- US
- United States
- Prior art keywords
- flame
- fuel
- closure
- control valve
- water heater
- 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
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 118
- 230000002401 inhibitory effect Effects 0.000 title description 2
- 238000002485 combustion reaction Methods 0.000 claims abstract description 50
- 239000000446 fuel Substances 0.000 claims abstract description 46
- 239000007789 gas Substances 0.000 claims description 111
- 230000000903 blocking effect Effects 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 4
- 239000000523 sample Substances 0.000 claims description 3
- 239000003517 fume Substances 0.000 description 47
- 239000010410 layer Substances 0.000 description 11
- 239000007788 liquid Substances 0.000 description 11
- 238000010276 construction Methods 0.000 description 10
- 238000010791 quenching Methods 0.000 description 10
- 230000008901 benefit Effects 0.000 description 9
- 230000000171 quenching effect Effects 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 239000004677 Nylon Substances 0.000 description 6
- 238000001514 detection method Methods 0.000 description 6
- 239000000428 dust Substances 0.000 description 6
- 239000003502 gasoline Substances 0.000 description 6
- 238000005304 joining Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 6
- 229920001778 nylon Polymers 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- 238000009413 insulation Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000001273 butane Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 235000003642 hunger Nutrition 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 230000013011 mating Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 230000037351 starvation Effects 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000000994 depressogenic effect Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000001294 propane Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000779819 Syncarpia glomulifera Species 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000000077 insect repellent Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000011490 mineral wool Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000001739 pinus spp. Substances 0.000 description 1
- 238000009428 plumbing Methods 0.000 description 1
- 239000002952 polymeric resin Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- YZHUMGUJCQRKBT-UHFFFAOYSA-M sodium chlorate Chemical compound [Na+].[O-]Cl(=O)=O YZHUMGUJCQRKBT-UHFFFAOYSA-M 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229940036248 turpentine Drugs 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/20—Arrangement or mounting of control or safety devices
- F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
- F24H9/2035—Arrangement or mounting of control or safety devices for water heaters using fluid fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/25—Temperature of the heat-generating means in the heater
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/305—Control of valves
- F24H15/31—Control of valves of valves having only one inlet port and one outlet port, e.g. flow rate regulating valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/355—Control of heat-generating means in heaters
- F24H15/36—Control of heat-generating means in heaters of burners
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D2209/00—Safety arrangements
- F23D2209/10—Flame flashback
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/18—Water-storage heaters
- F24H1/20—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes
- F24H1/205—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes with furnace tubes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/128—Preventing overheating
Definitions
- the present invention relates to ignition inhibiting gas fired water heaters, particularly to improvements to gas fired water heaters and controllers adapted to render them safer for use.
- the most commonly used gas-fired water heater is the storage type, generally comprising an assembly of a water tank, a main gas burner to provide heat to the tank, a standing pilot burner to initiate the main burner on demand, an air inlet adjacent the burner near the base of the jacket, an exhaust flue and a jacket to cover these components.
- Another type of gas-fired water heater is the instantaneous type which has a water flow path through a heat exchanger heated, again, by a main burner initiated from a pilot burner flame.
- the following description is in terms of storage type water heaters but the invention is not limited to this type.
- water container water containment and flow means
- water flow paths such as pipes, tubes, conduits, heat exchangers and the like in gas-fired water heaters of the instantaneous type.
- Vapors from spilt or escaping flammable liquid or gaseous substances in a space in which an ignition source is present provides for ignition potential.
- “Fumes,” “extraneous gases” or “extraneous fumes” is sometimes hereinafter used to encompass gases, vapors or fumes generated by a wide variety of liquid volatile or semi-volatile substances such as gasoline, kerosene, turpentine, alcohols, insect repellent, weed killer, solvents and the like as well as non-liquid substances such as propane, methane, butane and the like. Many inter-related factors influence whether a particular fuel spillage leads to ignition.
- One surrounding circumstance is the relative density of the fumes.
- a spilt liquid fuel spreads on a floor normal evaporation occurs and fumes from the liquid form a mixture with the surrounding air that may, at some time and at some locations, be within the range that will ignite.
- that range for common gasoline vapor is between about 3% and 8% gasoline with air, for butane between about 1% and 10%.
- Such mixtures form and spread by a combination of processes including natural diffusion, forced convection due to air current draughts and by gravitationally affected upward displacement of molecules of one less dense gas or vapor by those of another more dense.
- the invention aims to substantially lower the probability of ignition in typical fuel spillage circumstances.
- the invention provides a gas water heater including a water container adapted to be heated by a gas burner.
- An enclosure surrounds the burner and the water container.
- the water heater has at least one opening adapted to allow air for combustion or extraneous fumes to enter the enclosure without igniting flammable extraneous fumes outside of the enclosure.
- the invention provides a water heater having a burner adapted to combust gas to heat a water container above the burner within an outer enclosure having an opening to admit air required to combust the gas and includes air and extraneous fume flow means co-operative with the opening to reduce or eliminate a possibility of extraneous fumes adjacent the enclosure being ignited outside the enclosure by a gas flame associated with the burner.
- the invention also provides a water heater having a burner adapted to combust gas to heat a water container above the burner within an outer enclosure having an opening to air required to combust the gas and includes air and extraneous fume flow means cooperative with the opening to reduce or eliminate a possibility of fumes adjacent the enclosure being ignited outside the enclosure by a gas flame associated with the burner.
- the water heater includes gas shut off means which has a flame detecting or sensing device located in a path of flame external to a combustion chamber of the water heater and also located in any path of flame of fumes ignited in the enclosure.
- the invention provides a gas control valve of the type used to supply a main burner in a combustion chamber of a water heater which has an electrical circuit associated with the valve powered by a thermocouple heated by a pilot burner flame. The resulting electrical potential maintains a solenoid valve open which keeps the pilot supplied with gas for combustion. The valve closes down the gas supply for safety if the pilot flame blows out.
- the valve of the invention includes an over-temperature fuse in the electrical circuit specifically located to be exposed to extraneous sources of flame and heat in the immediate surroundings of the valve.
- the valve has an externally accessible socket in the electrical circuit such that the thermal fuse can be removably inserted in such a way that if the thermal fuse opens the electrical circuit by being heated above a predetermined temperature, then the fuse can be subsequently independently and separately replaced without having to interfere with other parts of the electrical circuit.
- FIG. 1 is a schematic partial cross-sectional view of a gas water heater embodying aspects of the invention.
- FIG. 2 is a schematic partial cross-sectional view of a gas water heater similar to FIG. 1, with additional safety features.
- FIG. 3 is a cross-sectional view of the water heater of FIG. 2 taken through the line III-III.
- FIG. 4 is a schematic partial cross-sectional view of a gas water heater similar to that of FIG. 2.
- FIG. 5 is a cross-sectional view of the water heater of FIG. 4 taken through line V-V.
- FIG. 6 is a schematic partial cross-sectional view of a gas water heater with a safety feature in accordance with aspects of the invention.
- FIG. 7 is a schematic partial cross-sectional view of a gas water heater of another embodiment of the invention.
- FIG. 8 is a schematic partial cross-sectional view of a gas water heater of yet another embodiment of the invention.
- FIG. 9 is a schematic partial cross-sectional view of still another embodiment of the invention.
- FIG. 10 is a cross-sectional view of the water heater of FIG. 9 taken through the line X-X.
- FIG. 11 is an upright elevational view taken from the rear of a gas valve according to the aspects of invention.
- FIG. 12 is an upright elevational showing the left side of the gas valve shown in FIG. 11.
- FIG. 13 is an upright perspective view of the valve of FIGS. 11 and 12.
- FIG. 14 is a schematic partial cross-sectional view of a water heater with the gas valve as shown in FIGS. 11 - 13 .
- FIG. 15 is an electrical circuit embodied in the gas valve shown in FIGS. 11 - 13 .
- FIG. 16 is a cross-sectional view of the gas valve shown in FIGS. 11 - 13 .
- FIG. 1 illustrates a storage type gas water heater 2 including jacket 4 which surrounds a water tank 6 , a main burner 14 in a combustion chamber 15 .
- Water tank 6 is preferably of mains pressure capability and capable of holding heated water.
- Water tank 6 is preferably insulated by foam insulation 8 .
- Alternative insulation may include fiberglass or other types of fibrous insulation and the like.
- main burner 14 Located underneath water tank 6 is main burner 14 which preferably uses natural gas or other gases such as LPG, for example.
- Main burner 14 combusts a gas and air mixture and the hot products of combustion resulting rise up through flue 10 .
- Flue 10 in this instance, contains a series of baffles 12 to better transfer heat generated by main burner 14 .
- Near pilot burner 49 is a sheath 52 , preferably made of copper, containing wires from a flame detecting thermocouple 51 which is a known safety measure to ensure that in the absence of a flame at pilot burner 49 the gas control valve 48 shuts off the gas supply.
- Duct 22 is preferably constructed from sheet metal 20 . In a non-illustrated alternative construction, a part or all of duct 22 may be inside the external cylindrical envelope of jacket 4 .
- Water heater 2 is preferably mounted on legs 24 to raise the base 26 off the floor.
- base 26 is an aperture 28 which is closed, but not gas tightly, by a flame trap device 30 which operates on a flame quenching principle.
- Flame trap 30 is preferably made from two parallel sheets of mesh each about 0.010 inch diameter metal wire strands woven into mesh having about 30 to 40 strands per inch. Mild steel or stainless steel wire are suitable.
- a ported ceramic tile of the SCHWANK type registered trade mark
- the tile type functions as a flame quenching trap as long as the porosity is suitable.
- a single layer of mesh or a porous ceramic tile may be susceptible to clogging by lint or other “blocking” materials such as dust or the like. Lint caught in the openings of a single mesh or a tile might act as a wick which may allow flame, which would not otherwise pass through the flame trap, to do so. In this situation the flame trap device would tend not to function as efficiently.
- the flame trap is preferably constructed with either two layers of mesh or a layer of mesh and a tile. The mesh layers are most preferably in contact with one another. In this way the layer of mesh further from the source of fumes acts as a flame trap and the layer closer to the source of fumes acts as a lint trap.
- mating surfaces 32 can be sealed thoroughly to prevent ingress of air or flammable gas or vapor.
- mating surfaces 32 extend upwardly from base 26 around jacket 4 .
- the cylindrical wall of jacket 4 (the majority of gas water heaters are cylindrical; however, a cubic or other shaped jacket 4 may be utilized) can be sealed gas tightly so no openings or breaks remain upon assembly and installation.
- gas, water, electrical, control or other connections, fittings or plumbing, wherever they pass through jacket 4 or base 26 can be sealed airtight.
- the joining area (or mating surfaces 32 ) of base 26 to jacket 4 and all service entries or exits to jacket 4 or duct 22 need not be sealed airtight providing they are designed and constructed to have only minor surface to surface clearances or gaps, each of which is capable of acting as flame quenching traps.
- the structure of such service entries or exits are known in the art and not described herein. It is preferred, however, that the space around the burner be substantially air/gas tight except for means to supply combustion air.
- Pilot flame establishment can be achieved by a Piezo-electric igniter.
- a pilot flame observation window can be provided which is sealed.
- safety interlocks (not illustrated) are included to ensure complete closure against unprotected fume access during water heater operation.
- water heater 2 operates in the same fashion as conventional water heaters except that most air for combustion enters at air inlet 18 and a small proportion through flame trap 30 .
- flame trap 30 allows the combustible gas or vapor and air to enter but prevents flame escaping jacket 4 or duct 22 .
- the spilt fuel is burned within combustion chamber 15 and exhausted either through flue 10 via outlet 16 and duct 19 or through duct 22 and inlet 18 (which in this case will act as an outlet). Because flame does not pass outwardly through flame trap 30 , spilt fuel external to water heater 2 will not be ignited.
- FIGS. 2 and 3 show an embodiment similar to that of FIG. 1. Like parts use the same reference numbers as those of FIG. 1.
- gas control valve 48 there is adjacent gas control valve 48 , a flame sensitive switch 50 which may be inserted in the same circuit as pilot flame detecting thermocouple 51 .
- Flame sensitive switch 50 may be substituted by a light detector or a heat detector.
- the flame sensitive switch can also be substituted by a gas, fume or vapor detection switch which closes off gas control valve 48 when a flammable fume is detected.
- duct 22 contains gas control valve 48 and flame trap 30 is shown forming a bottom end of the duct.
- flame trap 30 may be positioned spanning the bottom end of duct 22 and an adjacent portion of base 26 .
- An advantage from such a positioning of flame trap 30 including that shown in FIGS. 2 and 3, by comparison with the center position of base 26 shown in FIG. 1, is that it permits positioning of flame sensitive switch 50 (FIG. 2) directly below gas control valve 48 which is also an ideal position to detect flame spillage from combustion chamber 15 which can occur if, for example, flue 16 , or exhaust duct becomes blocked. Similarly, it is ideally positioned to detect flame spillage such as would occur due to air starvation if inlet 18 were inadvertently blocked.
- opening 28 and flame trap 30 are at the base of duct 22 below gas control valve 48 and flame detecting thermocouple 50 (see FIG. 2).
- gas control valve 48 In this way, should fumes which enter through flame trap 30 be ignited, a flame forms and burns on the inside surface of the flame trap and flame detecting switch 50 actuates the gas control valve 48 to shut off the gas supply, thus removing it as a continuing source of ignition.
- any vapors of spilt fuel continuing to enter through flame trap 30 may continue to burn because of the initial ignition and resulting suction of air and may continue to burn until there is insufficient flammable vapor remaining to be drawn in from the vicinity of water heater 2 .
- the path for air entry to main burner 14 is provided by a combined flame trap and duct 54 fabricated of metallic mesh 21 .
- This arrangement provides that combustion air passes through a flame quenching surface 21 and the height of duct 54 need not be as high as jacket 4 nor need it necessarily extend upwardly.
- it is preferably composed of separated layers 21 a and 21 b of metallic mesh. This two layer construction avoids a layer of lint, deposited externally, providing a possible combustion path through the mesh, as previously explained.
- Lint deposition in the openings of the mesh may be a cause of gradual blockage. In due course such linting may cause starvation of combustion air. Therefore, an extended surface area (along the full height of water heater 2 as depicted for instance) of the combined flame trap and air duct 54 may be of advantage for prolonging the time taken for duct 54 to become occluded with lint and for providing an adequate path for free induction of the air normally required for combustion.
- gas valve 48 in its preferred position is shown in FIG. 5 outside of duct 54 .
- the entry of the gas pipe and thermocouple sheath into duct 54 is effected so that if a hole is left it is small enough either to be totally sealed or to act as a flame quenching trap.
- gas valve 48 outside duct 54 provides one way of providing user access to the control knob and any buttons on gas control valve 48 . It would be equally applicable in cases where duct 22 is made of imperforate sheet metal 20 as shown in FIGS. 1 and 2.
- thermocouple sheath can enter water heater 2 via an opening in jacket 4 , completely bypassing duct 54 . This opening can then be sealed or if a gap is left, the gap is sized to act as a flame trap.
- flame sensitive switch 50 or other sensor is located in relation to the position of flame trap 30 so that the relative positions co-operate in the event that a flame from spilt fuel forms on the flame trap.
- FIG. 6 Illustrated in FIG. 6 is a another embodiment of the present invention, similar to that of FIG. 1, with like parts like numbered.
- This embodiment includes an anchor 34 which anchors a nylon line 36 which is a heat sensitive frangible member.
- the nylon line 36 passes close to the upper surface of flame trap 30 and around a lower pulley 38 then continues on to an upper pulley 40 around which it passes through 180 degrees, to make connection with a flap 42 .
- Flap 42 is connected by hinge 44 either to the inside of passage 22 or to a flange 46 .
- Flange 46 if it is utilized, can have a sealing medium (not illustrated) around it so that when flap 42 makes contact with it, an air tight seal or a flame trap is formed. If flange 46 is not utilized, flap 42 can carry a seal so that, when released to move to a closed position, it will seal the inside of duct 22 to air tight quality or, in the alternative to form a flame trap. Flap 42 can be biased towards the closed position by a spring, which is a preferred method, or alternatively the biasing can be by means of gravity. If desired, flap 42 can be constructed from mesh, as described above to act as a flame trap.
- FIGS. 7 and 8 are illustrated a gas water heater 2 constructed similarly to that illustrated in FIG. 1.
- Water heater 2 includes a base 26 and jacket 4 which are either completely sealed (not illustrated) to air tight and flammable gas or vapor tight quality or, alternatively, unsealed gas paths are fine (small) enough to act as flame traps. In this instance, when completely sealed, air for combustion is drawn in from the air inlet 18 , and there is no means present to ignite spilt fuel at the lower portions of water heater 2 .
- FIGS. 7 and 8 have no flame trap 30 or opening 28 .
- an appreciable time delay will occur before gases or vapors from spilt fuel rise to the elevated level of air inlet 18 . Only then could the gases or vapors be drawn down passage 22 to main burner 14 . Many spillages, nevertheless are quite minor in terms of volume of liquid spilt and in such cases the embodiment of FIG. 7 would tend to provide an adequate level of protection and that of FIG. 8 even more so.
- the air inlet 18 if it does not include a flame trap 30 , should be at least about 500 millimeters (20 inches) from base 26 (if base 26 is near to the ground), in the presence of gasoline fumes (a different height may be required for other fumes). However, for added protection a greater distance is preferred.
- base 26 and jacket 4 has small gaps or openings limited in their size to act as flame traps, then its operation will be similar to the embodiment of FIG. 1.
- the features of FIG. 6 can be incorporated also with the embodiments described in FIGS. 7 and 8 when base 26 and jacket 4 are scaled.
- the water heater now includes a heat sensitive frangible member 36 located in an air passage in the vicinity of the main burner 14 , if gases or vapors ignite having flowed down the passage 22 (which would indicate that the volume of gases or fumes had risen to the level of air entry of the air inlet 18 ), the resulting flame would melt a frangible member such as nylon line 36 in the vicinity of main burner 14 .
- Nylon line 36 can be connected in turn to a non-flammable and non-frangible section which in turn makes connection with a spring biased flap similar to flap 42 capable of sealing passage 22 .
- the distance between nylon line 36 and flap 42 is sufficiently long to close passage 22 before a flame travelling back up passage 22 reaches flap 42 . If flap 42 is hinged so that its closing motion is in the direction that flame would have to travel to exit passage 22 , the hinging arrangement may be aided in closing by the movement of flame in a closing direction.
- a further improvement to the above embodiments shown in FIGS. 1 - 6 is to provide a snorkel 60 as shown in FIG. 8 extending the air inlet upwardly.
- Snorkel 60 allows air to be drawn to main burner 14 but, by taking air from a height above the top of jacket 4 , will further reduce the risk of water heater 2 being an ignition source of flammable gases or vapors from spilt fuel. If the height of jacket 4 is not greater than about 500 millimeters (20 inches) above base 26 , snorkel 60 can be used to draw combustion air from a more appropriate height, depending upon the spillage which may occur.
- thermocouple 51 is preferably located just inside of the flame trap 30 where ever it appears. Flame sensitive switches may also be used in circuit with the thermocouple (e.g., thermocouple 51 of FIG. 1) provided for confirming the establishment and retention of a pilot flame by raising an electric current flow to a level capable of keeping open a gas supply to the pilot burner.
- Flame sensitive switches may be used to reduce fire hazards in circumstances where flame of the burner can “spill” through an air access opening adjacent the main and pilot burners.
- the heat sensor is externally positioned and in some embodiments of the invention a flame sensitive switch 50 is positioned above flame trap 30 to sense flame heat input resulting from spilt flammable vapor burning on the inside of flame trap 30 after having entered the combustion chamber through a possible entry path.
- the preferred position of the flame sensitive switch (not illustrated) is immediately above the flame trap and it is preferred that a small heat shield (not shown) be placed above the flame sensitive switch to shield it from the normal radiant heat associated with the main burner 14 .
- the flame sensitive switch 50 is positioned a short way above flame trap 30 .
- An additional level of safety is provided by the addition of an oxygen depletion sensor in conjunction with pilot burner 49 .
- This makes available the entire air requirement for the pilot flame to the pilot burner only through a pilot air duct (not illustrated), gas tightly separate from air supply duct 22 and combustion chamber 15 .
- the pilot air duct has an air intake external to the remainder of the water heater assembly, preferably low to floor level where water heaters are generally installed, standing upright on a floor.
- a flame quenching insert composed of one or more of a variety of high thermal capacity gas porous heat resistant materials such as described in relation to flame trap 30 . Locating the flame quenching insert at or near the air intake end is advantageous to make it accessible for cleaning of lint or dust that may accumulate in it.
- An element sensitive to oxygen depletion is also located in the pilot air duct.
- use of the oxygen depletion sensor reduces the risk of ignition of flammable vapor in particular when pilot burner 49 is alight but main burner 14 is not, by sensing oxygen depletion in the incoming pilot air supply if a flammable component ignites in which case it would cause a gas control valve 48 of the type referred to in FIG. 1 to shut down gas flow to the pilot burner.
- the shut down provides a time period for flammable vapor to safely ventilate.
- An oxygen depletion sensor can be used alternatively in place of or in conjunction with the previously described flame sensitive switch 50 , and can be located similarly.
- the invention thus far described can function at three levels of safety.
- the embodiment as illustrated in relation to FIGS. 7 and 8, adds height and distance that fumes from spilt fuel must travel to reach main burner 14 or pilot burner 49 .
- the second embodiment as illustrated in FIGS. 1, 2, 3 and 6 , adds not only height and distance but also allows some and advantageously all the extraneous fumes to enter the base of water heater 2 and be consumed safely, conceivably until all residual risk of fire and explosion is avoided by dissipation of the spillage.
- the third level adds a further level of confidence by protecting all air entry with a flame arrestor, recognizing that high levels of airborne lint or other dust may tend to block the air intake and starve the burner of air for combustion if the air entry were not periodically cleared of that lint or other dust.
- the embodiment of FIGS. 4 and 5 can be constructed to protect against ignition of flammable gases and vapors outside of the enclosure or jacket regardless of the density of those gases and vapors relative to air.
- water heater 2 contains at least some of the following features:
- the opening includes an aperture which is covered by a flame trap, which prevents the burner from igniting extraneous fumes outside of the enclosure, and an air inlet through which air for combustion purposes is drawn;
- the opening is remote from the burner and includes a duct for passage of air to the burner;
- the opening and the aperture are collocated or are a single item
- the at least one opening is covered by a flame trap
- the aperture is in the enclosure
- the aperture is positioned close to a lower end of the enclosure
- the aperture is positioned in a lower end of the enclosure
- the aperture is positioned below the burner
- the aperture is positioned to allow air and fumes outside of the water heater to enter into an air passage leading to the burner;
- the aperture allows air and fumes to enter the lowest point of the air passage
- one of or a combination of: a light detection or sensitive device; a flame detecting or sensitive device; a temperature sensitive or detecting device; a heat detecting or sensitive device; and an oxygen depletion sensitive or detection device, is located in the water heater to detect flame from the fumes if they have been ignited inside the enclosure;
- the opening includes an air inlet which is not covered by a flame trap, the air inlet having its lowest opening at a height of not less than about 500 millimeters or about 20 inches or more from the bottom of the enclosure;
- the opening is located at or adjacent to the highest point of the enclosure, if the enclosure has a height of about 500 millimeters or greater, from the bottom of the enclosure;
- a snorkel device is provided to extend the at least one opening to a height above the highest point of the enclosure
- the flame trap includes a heat resistant permeable material having high thermal capacity
- the flame trap includes a screen selected from either woven or knitted mesh
- the flame trap is made of metal
- the flame trap is made from a metal selected from the group consisting of: steel, stainless steel, copper and aluminum;
- a lint trap is included to wholly cover the aperture and the flame trap
- the lint trap is formed by mesh placed in the path of lint or dust travelling to the flame trap means;
- the water heater includes a gas shut off means which shuts off the gas supply to the burner and or a pilot burner if the air and fumes are ignited after entering the enclosure;
- the gas shut off means includes a heat sensitive means
- the gas shut off means includes a flame sensitive switch
- the gas shut off means includes an oxygen depletion sensitive means
- the enclosure comprises a separable jacket and base
- the flame trap is provided at or as part of the construction of joining areas of the base to the jacket, or the jacket to other component or the base to other component or at any location where the fumes could enter the enclosure;
- the flame trap is inherent in or is formed by the joining areas including either only gaps or apertures of a size small enough to act as a flame trap;
- the flame trap has been added to the joining area or is deliberately incorporated as part of the joining area;
- the flame trap is a layer of metallic mesh cooperating with the joining area to achieve the flame quenching or arresting function
- the flame trap is inside of the water heater
- the gas shut off means includes a light detection means.
- One advantage provided by the invention is the provision of a barrier to unprotected entry, at the lower end of the jacket or enclosure, of flammable extraneous fumes.
- it provides a protected entry means for such fumes near or at the base of the enclosure in which case these extraneous fumes are consumed in a controlled manner.
- the protected entry is, in the most preferred form, a flame trap preventing ignition of the remaining fumes in the surrounding atmosphere or of any liquid remaining nearby.
- An advantage of locating the air intake for combustion purposes above the midpoint of the gas water system is that it reduces the chance of extraneous fumes entering the heater via the air intake because generally such flammables are heavier than air, which in the main do not attain dangerous levels at the air intake level.
- air close-off means and gas shut-off means activated by a trigger provides the advantage of suffocating any flame in the heater, or switching off the gas supply, or preventing uncontrolled or undirected ignition of gases or vapors from exiting the heater environment.
- FIGS. 9 and 10 show water heater 2 wherein aperture 28 having flame trap 30 across its mouth and positioned below pilot burner 49 , pilot burner 49 being located adjacent one edge of main burner 14 .
- Aperture 28 is positioned immediately underneath pilot burner 49 , preferably the closer the better to assist in achieving smooth ignition.
- Aperture 28 is connected to the lower end of the enclosure by an upwardly extending tube 70 , the upwardly extending portion of tube 70 being preferably impermeable to air, gas or fumes.
- Tube 70 is preferably constructed of sheet metal, although other suitable materials may be substituted.
- Locating flame trap 30 above base 26 minimizes the possibility of water condensate occluding the pores or openings in flame trap 30 or water splashing from, for example, hosing the floor near base 26 of water heater 2 .
- the length of tube 70 is not especially critical so long as it performs the function of preventing pore occlusion.
- a horizontal blocking plate 74 is located above flame trap 28 to prevent water condensate or particulate matter such as steel scale flakes falling on the flame trap, thereby reducing the chance of occluding it.
- FIG. 9 illustrates a lint filter 72 in addition to a double layer flame trap 30 .
- Filter 72 may be a different material from flame trap 30 .
- the potential for accumulation of lint over time has been a concern.
- structure such as that shown in FIGS. 9 and 10 is surprisingly free of lint accumulation problems. It is believed that the horizontal and very close positioning of flame trap 30 to main burner 14 results in small pressure pulses associated with main burner 14 igniting on each occasion. Apparently, the pulses blow away any lint from the face of flame trap 30 . This appears to provide a repeating self-cleaning effect.
- thermocouple and over-temperature fuse have been inconveniently located in an integrated structure sheathed in a copper capillary tube with significant thermal inertia. If either the thermocouple or the temperature fuse require replacement then it is not immediately apparent which one has failed and, because both are replaced as an integrated unit, unnecessary cost is involved.
- the thermal fuse is a relatively low cost item compared to the entire integrated structure and, therefore, it is advantageous to be able to test the circuit by merely removing the suspect fuse and replacing it. This test does not involve removal of the thermocouple which requires awkward access into the water heater combustion chamber.
- FIGS. 11 - 14 show a gas control valve 48 supplying main burner 14 having an adjacent pilot burner 49 in water heater 2 with combustion chamber 15 , including a gas inlet 120 for connection to a supply (not shown) of combustible gas.
- Valve 48 has a gas outlet 124 for connection to a conduit (not shown) leading to main burner 14 and an outlet 126 to connect to pilot burner 49 .
- Internal components of the valve include an orifice or conduit 127 for gas flow between the inlet 120 and outlet 124 and a closure 154 normally resiliently biased to close the orifice to prevent or permit flow of gas from the inlet 120 to the outlet 124 as required.
- valve 48 Incorporated in valve 48 is an electrical circuit 128 such as shown in FIG. 15, including thermocouple 51 connected to a solenoid 132 .
- Thermocouple 51 provides an electrical potential, sometimes hereinafter referred to as “signal,” when heated by a flame established at pilot burner 49 , typically 12 to 15 mV, to solenoid 132 which is sufficient to maintain solenoid 132 open against the normally closing bias of a spring 156 associated with closure 154 .
- the electrical potential is provided to solenoid 32 , creating a magnetic force which, via an armature connected to closure 154 , maintains closure 154 open. It should be noted that the electrical potential is not sufficient to open closure 154 from its closed position except when valve passage 127 is first opened by manual switch 142 being manually positioned in the “pilot” or “on” positions and the potential is adequate to maintain closure 154 in its open position.
- valve 48 When a flame is absent at pilot burner 49 , valve 48 remains shut except during a start up procedure.
- the circuit has a manual switch 142 with three positions, “off”, “pilot” and “on”. In the “pilot” position the switch may be depressed to hold open valve 48 while thermocouple 51 heats sufficiently to power circuit 128 .
- Manual switch 142 is depressed in the “pilot” and “on” on positions to lift closure 154 off its seat against the closing bias force of spring 156 .
- an electrical current passing through the coil of solenoid 158 generated by the thermocouple 51 when heated by the flame of the pilot burner 49 (FIG. 4) is adequate to maintain closure 154 in the open position during normal use of water heater 2 . Normal use of water heater 2 involves pilot burner 49 being alight at all times.
- An over-temperature energy cut out 144 is installed inside a temperature sensitive thermostat probe 146 (shown in FIG. 12) which interrupts all gas flow through the valve in the event that an unsafe temperature develops inside the tank.
- valve 48 has a fuse 134 connected in electrical circuit 128 and exposed at the bottom surface of valve 48 to be sensitive to extraneous sources of flame and heat external to and in the region of the valve, particularly underneath it.
- Valve 48 features an externally accessible socket 136 in electrical circuit 128 in which thermal fuse 134 is removably inserted. Socket 136 is positioned to receive thermal fuse 134 independently and separate from thermocouple 51 .
- Socket 136 and fuse 134 are accessible from the underside of valve 48 as shown in FIGS. 11 and 14 wherein valve 48 is mounted on an external vertical wall of water heater 2 .
- Extraneous flame and heat within water heater 2 may result from accidental combustion of a flammable substance near water heater 2 , the flame being likely to establish itself firstly adjacent to access point 138 .
- fuse 134 Another advantage of mounting fuse 134 to be accessible at a downward facing surface of valve 48 is that fuse 134 would not be as noticeable upon a casual inspection of water heater 2 and valve 48 and, therefore, not so likely to invite removal by personnel unaware of its safety-motivated purpose. Water heater 2 will not continue to function if it were removed and not replaced.
- Fuse 134 has minimal thermal inertia and to that end involves minimal mass and is not enclosed in a copper or similar sheath.
- a preferred fuse 134 is one encapsulated only in a small quantity of organic polymer resin.
- One presently preferred form of thermal fuse 134 is manufactured by Therm-O-Disc, Inc., Mansfield, Ohio, USA.
- the radial lead type is the most suitable for insertion into a socket 136 and a model available with a maximum rated opening temperature of 102° C. has a suitably rapid response time.
- the flame trap may be located at various positions other than those shown in the drawings and described above.
- One alternative position is in the side of the combustion chamber opposite the gas supply. In such a construction the flame trap would be located in an opening in the skirt below the water tank and extending through the corresponding portion of insulation.
- the flame trap is positioned above the height of entry to the combustion chamber and the flame sensitive switch is positioned above that height of entry in the flow path of combustion air toward the burner.
- the aperture covered by the flame trap is in radiant heat communication with a flame sensitive switch also positioned to be sensitive to flame roll out from flue blockage or combustion air starvation.
- tube 70 as shown in FIG. 9 can be made either partially or completely from flame trap materials, especially the upper portion.
- the flame trap may be made from a variety of materials such as those described above, but can be fabricated from others not specifically identified so long as they permit passage of air and fumes in one direction but prevent flames from travelling in the opposite direction.
- Suitable flame trap materials include those being porous, gas permeable and possessing sufficiently high thermal capacity to quench flame under typical conditions of use.
- Metallic structures having small holes, made from, for example, mild steel, stainless steel, copper or aluminum are suitable and porous ceramics including glass or mineral wool woven or non-woven constructions are also suitable.
- Fibre matrix ceramic is suitable as is flexible or rigid constructions.
- the air passage for combustion air can be located between water tank 6 and jacket 4 .
- the passageway can be of a variety of shapes and sizes and can be formed in and bounded by the insulation or can be formed by tubes, pipes conduits and the like.
- thermocouples 51 providing electrical potentials may be employed so long as they are capable of converting heat energy to assist in actuating closure 154 .
- Heat to mechanical, heat to optical, heat to magnetic and the like types of conversions are all within the scope of the invention. Accordingly, “signal” as used in the claims refers not only to “electrical potential” but to any means whereby closure 154 is actuated/deactuated as a result of detection of heat energy.
- main burner 14 and combustion chamber 15 can have different constructions such as those described in U.S. Pat. Nos. 4,924,816; 5,240,411; 5,355,841; and co-pending applications 08/333,871 and 08/113,618, for example, the subject matter of which is incorporated herein by reference.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- Control Of Combustion (AREA)
Abstract
A water heater including a water container having an inlet and an outlet; a main burner positioned to heat water in the water container; a pilot burner positioned to supply flame to the main burner; and a control valve to supply fuel to the main and pilot burners.
The control valve includes a fuel inlet adapted to connect to a supply of fuel; at least one fuel outlet adapted to connect to the main burner; a conduit for fuel flow between the inlet and outlet; a closure associated with the conduit to control flow of fuel from the inlet to the outlet; a circuit associated with the valve and including a thermally actuated device connected to the closure, the switch, when heated by the pilot burner providing a signal to the closure to open or close said closure; and a combustion sensitive fuse connected to the electrical circuit and positioned to be exposed to extraneous sources of flame and heat external to and adjacent the control valve.
Description
- The present invention relates to ignition inhibiting gas fired water heaters, particularly to improvements to gas fired water heaters and controllers adapted to render them safer for use.
- The most commonly used gas-fired water heater is the storage type, generally comprising an assembly of a water tank, a main gas burner to provide heat to the tank, a standing pilot burner to initiate the main burner on demand, an air inlet adjacent the burner near the base of the jacket, an exhaust flue and a jacket to cover these components. Another type of gas-fired water heater is the instantaneous type which has a water flow path through a heat exchanger heated, again, by a main burner initiated from a pilot burner flame. For convenience, the following description is in terms of storage type water heaters but the invention is not limited to this type. Thus, reference to “water container,” “water containment and flow means,” “means for storing or containing water” and similar such terms includes water tanks, reservoirs, bladders, bags and the like in gas-fired water heaters of the storage type and water flow paths such as pipes, tubes, conduits, heat exchangers and the like in gas-fired water heaters of the instantaneous type.
- A particular difficulty with many locations for water heaters is that they are also used for storage of other equipment such as lawn mowers, trimmers, snow blowers and the like. It is common for such machinery to be refueled in such locations.
- There have been a number of reported instances of spilled gasoline and associated fumes being accidently ignited. There are many available ignition sources, such as refrigerators, running engines, electric motors, electric light switches and the like. However, gas water heaters have sometimes been suspected because they often have a pilot flame.
- Vapors from spilt or escaping flammable liquid or gaseous substances in a space in which an ignition source is present provides for ignition potential. “Fumes,” “extraneous gases” or “extraneous fumes” is sometimes hereinafter used to encompass gases, vapors or fumes generated by a wide variety of liquid volatile or semi-volatile substances such as gasoline, kerosene, turpentine, alcohols, insect repellent, weed killer, solvents and the like as well as non-liquid substances such as propane, methane, butane and the like. Many inter-related factors influence whether a particular fuel spillage leads to ignition. These factors include, among other things, the quantity, nature and physical properties of the particular type of spilt fuel. Also influential is whether air currents in the room, either natural or artificially created, are sufficient to accelerate the spread of fumes, both laterally and in height, from the spillage point to an ignition point yet not so strong as to ventilate such fumes harmlessly, that is, such that air to fuel ratio ranges capable of enabling ignition are not reached given all the surrounding circumstances.
- One surrounding circumstance is the relative density of the fumes. When a spilt liquid fuel spreads on a floor, normal evaporation occurs and fumes from the liquid form a mixture with the surrounding air that may, at some time and at some locations, be within the range that will ignite. For example, that range for common gasoline vapor is between about 3% and 8% gasoline with air, for butane between about 1% and 10%. Such mixtures form and spread by a combination of processes including natural diffusion, forced convection due to air current draughts and by gravitationally affected upward displacement of molecules of one less dense gas or vapor by those of another more dense. Most common fuels stored in households are, as used, either gases with densities relatively close to that of air (e.g., propane and butane) or liquids which form fumes having a density close to that of air, (e.g., gasoline, which may contain butane and pentane among other components is very typical of such a liquid fuel).
- In reconstructions of accidental ignition situations, and when gas water heaters are sometimes suspected and which involved spilt fuels typically used around households, it is reported that the spillage is sometimes at floor level. It is reasoned that it spreads outwardly from the spill at first close to floor level. Without appreciable forced mixing, the air/fuel mixture would tend to be at its most flammable levels close to floor level for a longer period before it would slowly diffuse towards the ceiling of the room space. The principal reason for this observation is that the density of fumes typically involved is not greatly dissimilar to that of air. Combined with the tendency of ignitable concentrations of fumes being at or near floor level is the fact that many gas appliances often have their source of ignition at or near that level.
- The invention aims to substantially lower the probability of ignition in typical fuel spillage circumstances.
- The invention provides a gas water heater including a water container adapted to be heated by a gas burner. An enclosure surrounds the burner and the water container. The water heater has at least one opening adapted to allow air for combustion or extraneous fumes to enter the enclosure without igniting flammable extraneous fumes outside of the enclosure.
- In another aspect, the invention provides a water heater having a burner adapted to combust gas to heat a water container above the burner within an outer enclosure having an opening to admit air required to combust the gas and includes air and extraneous fume flow means co-operative with the opening to reduce or eliminate a possibility of extraneous fumes adjacent the enclosure being ignited outside the enclosure by a gas flame associated with the burner.
- The invention also provides a water heater having a burner adapted to combust gas to heat a water container above the burner within an outer enclosure having an opening to air required to combust the gas and includes air and extraneous fume flow means cooperative with the opening to reduce or eliminate a possibility of fumes adjacent the enclosure being ignited outside the enclosure by a gas flame associated with the burner. The water heater includes gas shut off means which has a flame detecting or sensing device located in a path of flame external to a combustion chamber of the water heater and also located in any path of flame of fumes ignited in the enclosure.
- In yet another aspect, the invention provides a gas control valve of the type used to supply a main burner in a combustion chamber of a water heater which has an electrical circuit associated with the valve powered by a thermocouple heated by a pilot burner flame. The resulting electrical potential maintains a solenoid valve open which keeps the pilot supplied with gas for combustion. The valve closes down the gas supply for safety if the pilot flame blows out. The valve of the invention includes an over-temperature fuse in the electrical circuit specifically located to be exposed to extraneous sources of flame and heat in the immediate surroundings of the valve. The valve has an externally accessible socket in the electrical circuit such that the thermal fuse can be removably inserted in such a way that if the thermal fuse opens the electrical circuit by being heated above a predetermined temperature, then the fuse can be subsequently independently and separately replaced without having to interfere with other parts of the electrical circuit.
- Selected embodiments of the invention will now be described, by way of example only, by reference to the accompanying drawings in which:
- FIG. 1 is a schematic partial cross-sectional view of a gas water heater embodying aspects of the invention.
- FIG. 2 is a schematic partial cross-sectional view of a gas water heater similar to FIG. 1, with additional safety features.
- FIG. 3 is a cross-sectional view of the water heater of FIG. 2 taken through the line III-III.
- FIG. 4 is a schematic partial cross-sectional view of a gas water heater similar to that of FIG. 2.
- FIG. 5 is a cross-sectional view of the water heater of FIG. 4 taken through line V-V.
- FIG. 6 is a schematic partial cross-sectional view of a gas water heater with a safety feature in accordance with aspects of the invention.
- FIG. 7 is a schematic partial cross-sectional view of a gas water heater of another embodiment of the invention.
- FIG. 8 is a schematic partial cross-sectional view of a gas water heater of yet another embodiment of the invention.
- FIG. 9 is a schematic partial cross-sectional view of still another embodiment of the invention.
- FIG. 10 is a cross-sectional view of the water heater of FIG. 9 taken through the line X-X.
- FIG. 11 is an upright elevational view taken from the rear of a gas valve according to the aspects of invention.
- FIG. 12 is an upright elevational showing the left side of the gas valve shown in FIG. 11.
- FIG. 13 is an upright perspective view of the valve of FIGS. 11 and 12.
- FIG. 14 is a schematic partial cross-sectional view of a water heater with the gas valve as shown in FIGS.11-13.
- FIG. 15 is an electrical circuit embodied in the gas valve shown in FIGS.11-13.
- FIG. 16 is a cross-sectional view of the gas valve shown in FIGS.11-13.
- It will be appreciated that the following description is intended to refer to the specific embodiments of the invention selected for illustration in the drawings and is not intended to define or limit the invention other than in the appended claims.
- FIG. 1 illustrates a storage type
gas water heater 2 includingjacket 4 which surrounds awater tank 6, amain burner 14 in acombustion chamber 15.Water tank 6 is preferably of mains pressure capability and capable of holding heated water.Water tank 6 is preferably insulated byfoam insulation 8. Alternative insulation may include fiberglass or other types of fibrous insulation and the like. - Located underneath
water tank 6 ismain burner 14 which preferably uses natural gas or other gases such as LPG, for example.Main burner 14 combusts a gas and air mixture and the hot products of combustion resulting rise up throughflue 10.Flue 10, in this instance, contains a series ofbaffles 12 to better transfer heat generated bymain burner 14. Nearpilot burner 49 is asheath 52, preferably made of copper, containing wires from aflame detecting thermocouple 51 which is a known safety measure to ensure that in the absence of a flame atpilot burner 49 thegas control valve 48 shuts off the gas supply. - The products of combustion pass upwardly and out the top of
jacket 4 viaflue outlet 16 after heat has been transferred from the products of combustion.Flue outlet 16 discharges conventionally into adraught diverter 17 which in turn connects to anexhaust duct 19 leading outdoors. - Close to the height of the top of
jacket 4 andflue outlet 16 is anair inlet 18 through which air is drawn downduct 22 tomain burner 14.Duct 22 is preferably constructed fromsheet metal 20. In a non-illustrated alternative construction, a part or all ofduct 22 may be inside the external cylindrical envelope ofjacket 4. -
Water heater 2 is preferably mounted onlegs 24 to raise the base 26 off the floor. Inbase 26 is anaperture 28 which is closed, but not gas tightly, by aflame trap device 30 which operates on a flame quenching principle.Flame trap 30 is preferably made from two parallel sheets of mesh each about 0.010 inch diameter metal wire strands woven into mesh having about 30 to 40 strands per inch. Mild steel or stainless steel wire are suitable. Alternatively, a ported ceramic tile of the SCHWANK type (registered trade mark) can be utilized although the recognized flame quenching ability of metallic woven or knitted mesh together with its robustness and ease of forming generally commends its use. The tile type functions as a flame quenching trap as long as the porosity is suitable. - A single layer of mesh or a porous ceramic tile may be susceptible to clogging by lint or other “blocking” materials such as dust or the like. Lint caught in the openings of a single mesh or a tile might act as a wick which may allow flame, which would not otherwise pass through the flame trap, to do so. In this situation the flame trap device would tend not to function as efficiently. To prevent this tendency, the flame trap is preferably constructed with either two layers of mesh or a layer of mesh and a tile. The mesh layers are most preferably in contact with one another. In this way the layer of mesh further from the source of fumes acts as a flame trap and the layer closer to the source of fumes acts as a lint trap.
- Where
base 26 meetsjacket 4, mating surfaces 32 (made up from surfaces ofbase 26 and jacket 4) can be sealed thoroughly to prevent ingress of air or flammable gas or vapor. In FIG. 1, mating surfaces 32 extend upwardly frombase 26 aroundjacket 4. The cylindrical wall of jacket 4 (the majority of gas water heaters are cylindrical; however, a cubic or other shapedjacket 4 may be utilized) can be sealed gas tightly so no openings or breaks remain upon assembly and installation. In particular, gas, water, electrical, control or other connections, fittings or plumbing, wherever they pass throughjacket 4 orbase 26, can be sealed airtight. The joining area (or mating surfaces 32) ofbase 26 tojacket 4 and all service entries or exits tojacket 4 orduct 22 need not be sealed airtight providing they are designed and constructed to have only minor surface to surface clearances or gaps, each of which is capable of acting as flame quenching traps. The structure of such service entries or exits are known in the art and not described herein. It is preferred, however, that the space around the burner be substantially air/gas tight except for means to supply combustion air. - Pilot flame establishment can be achieved by a Piezo-electric igniter. A pilot flame observation window can be provided which is sealed. Alternatively, if the
pilot 49 is to be lit by removing or opening an access, safety interlocks (not illustrated) are included to ensure complete closure against unprotected fume access during water heater operation. - During normal operation,
water heater 2 operates in the same fashion as conventional water heaters except that most air for combustion enters atair inlet 18 and a small proportion throughflame trap 30. However, if spilt fuel is in the vicinity ofwater heater 2 then some gas or vapor from the spilt fuel may be drawn throughflame trap 30 before it builds up to a level to enter viaair inlet 18.Flame trap 30 allows the combustible gas or vapor and air to enter but preventsflame escaping jacket 4 orduct 22. The spilt fuel is burned withincombustion chamber 15 and exhausted either throughflue 10 viaoutlet 16 andduct 19 or throughduct 22 and inlet 18 (which in this case will act as an outlet). Because flame does not pass outwardly throughflame trap 30, spilt fuel external towater heater 2 will not be ignited. - FIGS. 2 and 3 show an embodiment similar to that of FIG. 1. Like parts use the same reference numbers as those of FIG. 1. In FIG. 2, there is adjacent
gas control valve 48, a flamesensitive switch 50 which may be inserted in the same circuit as pilotflame detecting thermocouple 51. - Flame
sensitive switch 50 may be substituted by a light detector or a heat detector. The flame sensitive switch can also be substituted by a gas, fume or vapor detection switch which closes offgas control valve 48 when a flammable fume is detected. - With reference to the cross section depicted in FIG. 3,
duct 22 containsgas control valve 48 andflame trap 30 is shown forming a bottom end of the duct. In fact,flame trap 30 may be positioned spanning the bottom end ofduct 22 and an adjacent portion ofbase 26. An advantage from such a positioning offlame trap 30, including that shown in FIGS. 2 and 3, by comparison with the center position ofbase 26 shown in FIG. 1, is that it permits positioning of flame sensitive switch 50 (FIG. 2) directly belowgas control valve 48 which is also an ideal position to detect flame spillage fromcombustion chamber 15 which can occur if, for example,flue 16, or exhaust duct becomes blocked. Similarly, it is ideally positioned to detect flame spillage such as would occur due to air starvation ifinlet 18 were inadvertently blocked. - As shown in FIGS. 2 and 3, opening28 and flame trap 30 (including a lint trap device as mentioned above) are at the base of
duct 22 belowgas control valve 48 and flame detecting thermocouple 50 (see FIG. 2). In this way, should fumes which enter throughflame trap 30 be ignited, a flame forms and burns on the inside surface of the flame trap andflame detecting switch 50 actuates thegas control valve 48 to shut off the gas supply, thus removing it as a continuing source of ignition. After the pilot and main flames have been extinguished, any vapors of spilt fuel continuing to enter throughflame trap 30 may continue to burn because of the initial ignition and resulting suction of air and may continue to burn until there is insufficient flammable vapor remaining to be drawn in from the vicinity ofwater heater 2. - By providing an
air inlet 18 at a high position above thebase 26, the more commonplace liquid fuels, the flammable gases and vapors are far less likely to be available to a gas water heater flame. - In the
water heater 2 of FIGS. 4 and 5, the path for air entry tomain burner 14 is provided by a combined flame trap andduct 54 fabricated ofmetallic mesh 21. This arrangement provides that combustion air passes through aflame quenching surface 21 and the height ofduct 54 need not be as high asjacket 4 nor need it necessarily extend upwardly. As evident in FIG. 5, it is preferably composed of separatedlayers - Lint deposition in the openings of the mesh may be a cause of gradual blockage. In due course such linting may cause starvation of combustion air. Therefore, an extended surface area (along the full height of
water heater 2 as depicted for instance) of the combined flame trap andair duct 54 may be of advantage for prolonging the time taken forduct 54 to become occluded with lint and for providing an adequate path for free induction of the air normally required for combustion. - The positioning of
gas valve 48 in its preferred position is shown in FIG. 5 outside ofduct 54. The entry of the gas pipe and thermocouple sheath intoduct 54 is effected so that if a hole is left it is small enough either to be totally sealed or to act as a flame quenching trap. - The preference for
gas valve 48 outsideduct 54 is that it provides one way of providing user access to the control knob and any buttons ongas control valve 48. It would be equally applicable in cases whereduct 22 is made ofimperforate sheet metal 20 as shown in FIGS. 1 and 2. - For ease of construction one option is that the gas pipe and thermocouple sheath can enter
water heater 2 via an opening injacket 4, completely bypassingduct 54. This opening can then be sealed or if a gap is left, the gap is sized to act as a flame trap. However, whichever way the thermocouple sheath passes to enter the combustion chamber, if it includes flamesensitive switch 50 or other equivalent sensor, then it is greatly preferred that the flamesensitive switch 50 or other sensor is located in relation to the position offlame trap 30 so that the relative positions co-operate in the event that a flame from spilt fuel forms on the flame trap. - Illustrated in FIG. 6 is a another embodiment of the present invention, similar to that of FIG. 1, with like parts like numbered. This embodiment includes an anchor34 which anchors a
nylon line 36 which is a heat sensitive frangible member. Thenylon line 36 passes close to the upper surface offlame trap 30 and around alower pulley 38 then continues on to anupper pulley 40 around which it passes through 180 degrees, to make connection with aflap 42.Flap 42 is connected byhinge 44 either to the inside ofpassage 22 or to aflange 46. -
Flange 46, if it is utilized, can have a sealing medium (not illustrated) around it so that whenflap 42 makes contact with it, an air tight seal or a flame trap is formed. Ifflange 46 is not utilized,flap 42 can carry a seal so that, when released to move to a closed position, it will seal the inside ofduct 22 to air tight quality or, in the alternative to form a flame trap.Flap 42 can be biased towards the closed position by a spring, which is a preferred method, or alternatively the biasing can be by means of gravity. If desired,flap 42 can be constructed from mesh, as described above to act as a flame trap. - In the embodiment of FIG. 6, when fumes from split fuel passing through the
flame trap 30 are ignited, the heat of ignition breaksnylon line 36, which is heat sensitive and frangible, thereby causingflap 42 to move to a closed position, shutting off the air supply tomain burner 14. This leaves no path downduct 22 for air or combustible fumes which may have built up aroundwater heater 2 to sufficiently gain access tomain burner 14 and sopilot burner 49 andmain burner 14 may not have enough air available throughflame trap 30 to continue burning in which caseflame detection thermocouple 50 will cut off the gas supply until manual intervention can restore it when a safe atmosphere is restored. - In FIGS. 7 and 8 are illustrated a
gas water heater 2 constructed similarly to that illustrated in FIG. 1.Water heater 2 includes abase 26 andjacket 4 which are either completely sealed (not illustrated) to air tight and flammable gas or vapor tight quality or, alternatively, unsealed gas paths are fine (small) enough to act as flame traps. In this instance, when completely sealed, air for combustion is drawn in from theair inlet 18, and there is no means present to ignite spilt fuel at the lower portions ofwater heater 2. - The embodiments shown in FIGS. 7 and 8 have no
flame trap 30 oropening 28. However, an appreciable time delay will occur before gases or vapors from spilt fuel rise to the elevated level ofair inlet 18. Only then could the gases or vapors be drawn downpassage 22 tomain burner 14. Many spillages, nevertheless are quite minor in terms of volume of liquid spilt and in such cases the embodiment of FIG. 7 would tend to provide an adequate level of protection and that of FIG. 8 even more so. Theair inlet 18, if it does not include aflame trap 30, should be at least about 500 millimeters (20 inches) from base 26 (ifbase 26 is near to the ground), in the presence of gasoline fumes (a different height may be required for other fumes). However, for added protection a greater distance is preferred. - The more frequently used typical flammable fumes of spilt liquid fuels are far less likely to be available to a gas water heater flame by providing an
air inlet 18 at a high position abovebase 26. - If
base 26 andjacket 4 has small gaps or openings limited in their size to act as flame traps, then its operation will be similar to the embodiment of FIG. 1. The features of FIG. 6 can be incorporated also with the embodiments described in FIGS. 7 and 8 whenbase 26 andjacket 4 are scaled. In this instance, because the water heater now includes a heat sensitivefrangible member 36 located in an air passage in the vicinity of themain burner 14, if gases or vapors ignite having flowed down the passage 22 (which would indicate that the volume of gases or fumes had risen to the level of air entry of the air inlet 18), the resulting flame would melt a frangible member such asnylon line 36 in the vicinity ofmain burner 14.Nylon line 36 can be connected in turn to a non-flammable and non-frangible section which in turn makes connection with a spring biased flap similar toflap 42 capable of sealingpassage 22. The distance betweennylon line 36 andflap 42 is sufficiently long to closepassage 22 before a flame travelling back uppassage 22reaches flap 42. Ifflap 42 is hinged so that its closing motion is in the direction that flame would have to travel to exitpassage 22, the hinging arrangement may be aided in closing by the movement of flame in a closing direction. - A further improvement to the above embodiments shown in FIGS.1-6 is to provide a
snorkel 60 as shown in FIG. 8 extending the air inlet upwardly.Snorkel 60 allows air to be drawn tomain burner 14 but, by taking air from a height above the top ofjacket 4, will further reduce the risk ofwater heater 2 being an ignition source of flammable gases or vapors from spilt fuel. If the height ofjacket 4 is not greater than about 500 millimeters (20 inches) abovebase 26, snorkel 60 can be used to draw combustion air from a more appropriate height, depending upon the spillage which may occur. - In conjunction with any form of the invention as shown in FIGS.1 to 6, a gas shut down facility similar to the above mentioned gas shut down ability can be provided. In another form, the gas shut down facility can be initiated by a flame
sensitive switch 50 orthermocouple 51. Such a thermocouple is preferably located just inside of theflame trap 30 where ever it appears. Flame sensitive switches may also be used in circuit with the thermocouple (e.g.,thermocouple 51 of FIG. 1) provided for confirming the establishment and retention of a pilot flame by raising an electric current flow to a level capable of keeping open a gas supply to the pilot burner. - Flame sensitive switches may be used to reduce fire hazards in circumstances where flame of the burner can “spill” through an air access opening adjacent the main and pilot burners. In known flame sensitive switches, the heat sensor is externally positioned and in some embodiments of the invention a flame
sensitive switch 50 is positioned aboveflame trap 30 to sense flame heat input resulting from spilt flammable vapor burning on the inside offlame trap 30 after having entered the combustion chamber through a possible entry path. In the embodiment of FIG. 1, the preferred position of the flame sensitive switch (not illustrated) is immediately above the flame trap and it is preferred that a small heat shield (not shown) be placed above the flame sensitive switch to shield it from the normal radiant heat associated with themain burner 14. In FIG. 2, the flamesensitive switch 50 is positioned a short way aboveflame trap 30. - An additional level of safety is provided by the addition of an oxygen depletion sensor in conjunction with
pilot burner 49. This makes available the entire air requirement for the pilot flame to the pilot burner only through a pilot air duct (not illustrated), gas tightly separate fromair supply duct 22 andcombustion chamber 15. The pilot air duct has an air intake external to the remainder of the water heater assembly, preferably low to floor level where water heaters are generally installed, standing upright on a floor. At any convenient location in the pilot air duct between the air intake end and the pilot burner is a flame quenching insert, composed of one or more of a variety of high thermal capacity gas porous heat resistant materials such as described in relation toflame trap 30. Locating the flame quenching insert at or near the air intake end is advantageous to make it accessible for cleaning of lint or dust that may accumulate in it. An element sensitive to oxygen depletion is also located in the pilot air duct. - With these features added to the embodiments of FIGS.1 to 7, use of the oxygen depletion sensor reduces the risk of ignition of flammable vapor in particular when
pilot burner 49 is alight butmain burner 14 is not, by sensing oxygen depletion in the incoming pilot air supply if a flammable component ignites in which case it would cause agas control valve 48 of the type referred to in FIG. 1 to shut down gas flow to the pilot burner. The shut down provides a time period for flammable vapor to safely ventilate. Resumption of normal operation of the water heater requires human intervention but, even if done ill-advisedly, in any event the oxygen depletion sensor would continue to denypilot burner 49 of gas and the arrangement would behave safely even with extraneous flammable fumes remaining nearwater heater 2. An oxygen depletion sensor can be used alternatively in place of or in conjunction with the previously described flamesensitive switch 50, and can be located similarly. - The invention thus far described can function at three levels of safety. The embodiment, as illustrated in relation to FIGS. 7 and 8, adds height and distance that fumes from spilt fuel must travel to reach
main burner 14 orpilot burner 49. The second embodiment, as illustrated in FIGS. 1, 2, 3 and 6, adds not only height and distance but also allows some and advantageously all the extraneous fumes to enter the base ofwater heater 2 and be consumed safely, conceivably until all residual risk of fire and explosion is avoided by dissipation of the spillage. - The third level, as illustrated in FIGS. 4 and 5, adds a further level of confidence by protecting all air entry with a flame arrestor, recognizing that high levels of airborne lint or other dust may tend to block the air intake and starve the burner of air for combustion if the air entry were not periodically cleared of that lint or other dust. The embodiment of FIGS. 4 and 5 can be constructed to protect against ignition of flammable gases and vapors outside of the enclosure or jacket regardless of the density of those gases and vapors relative to air.
- In its most preferred
forms water heater 2 contains at least some of the following features: - the opening includes an aperture which is covered by a flame trap, which prevents the burner from igniting extraneous fumes outside of the enclosure, and an air inlet through which air for combustion purposes is drawn;
- the opening is remote from the burner and includes a duct for passage of air to the burner;
- the opening and the aperture are collocated or are a single item;
- the at least one opening is covered by a flame trap;
- the aperture is in the enclosure;
- the aperture is positioned close to a lower end of the enclosure;
- the aperture is positioned in a lower end of the enclosure;
- the aperture is positioned below the burner;
- the aperture is positioned to allow air and fumes outside of the water heater to enter into an air passage leading to the burner;
- the aperture allows air and fumes to enter the lowest point of the air passage;
- one of or a combination of: a light detection or sensitive device; a flame detecting or sensitive device; a temperature sensitive or detecting device; a heat detecting or sensitive device; and an oxygen depletion sensitive or detection device, is located in the water heater to detect flame from the fumes if they have been ignited inside the enclosure;
- the opening includes an air inlet which is not covered by a flame trap, the air inlet having its lowest opening at a height of not less than about 500 millimeters or about 20 inches or more from the bottom of the enclosure;
- the opening is located at or adjacent to the highest point of the enclosure, if the enclosure has a height of about 500 millimeters or greater, from the bottom of the enclosure;
- a snorkel device is provided to extend the at least one opening to a height above the highest point of the enclosure;
- the flame trap includes a heat resistant permeable material having high thermal capacity;
- the flame trap includes a screen selected from either woven or knitted mesh;
- the flame trap is made of metal;
- the flame trap is made from a metal selected from the group consisting of: steel, stainless steel, copper and aluminum;
- a lint trap is included to wholly cover the aperture and the flame trap;
- the lint trap is formed by mesh placed in the path of lint or dust travelling to the flame trap means;
- the water heater includes a gas shut off means which shuts off the gas supply to the burner and or a pilot burner if the air and fumes are ignited after entering the enclosure;
- the gas shut off means includes a heat sensitive means;
- the gas shut off means includes a flame sensitive switch;
- the gas shut off means includes an oxygen depletion sensitive means;
- the enclosure comprises a separable jacket and base;
- the flame trap is provided at or as part of the construction of joining areas of the base to the jacket, or the jacket to other component or the base to other component or at any location where the fumes could enter the enclosure;
- the flame trap is inherent in or is formed by the joining areas including either only gaps or apertures of a size small enough to act as a flame trap;
- the flame trap has been added to the joining area or is deliberately incorporated as part of the joining area;
- the flame trap is a layer of metallic mesh cooperating with the joining area to achieve the flame quenching or arresting function;
- the flame trap is inside of the water heater; and
- the gas shut off means includes a light detection means.
- One advantage provided by the invention is the provision of a barrier to unprotected entry, at the lower end of the jacket or enclosure, of flammable extraneous fumes. In alternative embodiments it provides a protected entry means for such fumes near or at the base of the enclosure in which case these extraneous fumes are consumed in a controlled manner. The protected entry is, in the most preferred form, a flame trap preventing ignition of the remaining fumes in the surrounding atmosphere or of any liquid remaining nearby.
- An advantage of locating the air intake for combustion purposes above the midpoint of the gas water system is that it reduces the chance of extraneous fumes entering the heater via the air intake because generally such flammables are heavier than air, which in the main do not attain dangerous levels at the air intake level.
- The use of air close-off means and gas shut-off means activated by a trigger provides the advantage of suffocating any flame in the heater, or switching off the gas supply, or preventing uncontrolled or undirected ignition of gases or vapors from exiting the heater environment.
- By providing an extended air intake, the risk of lint or dust affecting the efficiency of the water heater is reduced.
- Still further advantages of the invention are provided by the structure shown in FIGS. 9 and 10. FIGS. 9 and 10
show water heater 2 whereinaperture 28 havingflame trap 30 across its mouth and positioned belowpilot burner 49,pilot burner 49 being located adjacent one edge ofmain burner 14.Aperture 28 is positioned immediately underneathpilot burner 49, preferably the closer the better to assist in achieving smooth ignition.Aperture 28 is connected to the lower end of the enclosure by an upwardly extendingtube 70, the upwardly extending portion oftube 70 being preferably impermeable to air, gas or fumes.Tube 70 is preferably constructed of sheet metal, although other suitable materials may be substituted. Locatingflame trap 30 abovebase 26 minimizes the possibility of water condensate occluding the pores or openings inflame trap 30 or water splashing from, for example, hosing the floor nearbase 26 ofwater heater 2. Thus, the length oftube 70 is not especially critical so long as it performs the function of preventing pore occlusion. In FIG. 9, ahorizontal blocking plate 74 is located aboveflame trap 28 to prevent water condensate or particulate matter such as steel scale flakes falling on the flame trap, thereby reducing the chance of occluding it. - It has also been discovered that a two layer construction of
flame trap 30 with a lint filter is highly advantageous. FIG. 9 illustrates alint filter 72 in addition to a doublelayer flame trap 30.Filter 72 may be a different material fromflame trap 30. The potential for accumulation of lint over time has been a concern. However, it has been unexpectedly discovered that structure such as that shown in FIGS. 9 and 10 is surprisingly free of lint accumulation problems. It is believed that the horizontal and very close positioning offlame trap 30 tomain burner 14 results in small pressure pulses associated withmain burner 14 igniting on each occasion. Apparently, the pulses blow away any lint from the face offlame trap 30. This appears to provide a repeating self-cleaning effect. - Another significant advantage of the water heater of the invention is its improved gas control valve. In conventional gas valves, the thermocouple and over-temperature fuse have been inconveniently located in an integrated structure sheathed in a copper capillary tube with significant thermal inertia. If either the thermocouple or the temperature fuse require replacement then it is not immediately apparent which one has failed and, because both are replaced as an integrated unit, unnecessary cost is involved. The thermal fuse is a relatively low cost item compared to the entire integrated structure and, therefore, it is advantageous to be able to test the circuit by merely removing the suspect fuse and replacing it. This test does not involve removal of the thermocouple which requires awkward access into the water heater combustion chamber. Thus, there can be a considerable reduction in the time a water heater serviceperson needs to identify and correct a problem in the many cases where an open circuit is related to the fuse rather than the thermocouple. Therefore, the reason for replacement being necessary can be ascertained more directly and, thus, safe operation resumed more certainly.
- FIGS.11-14 show a
gas control valve 48 supplyingmain burner 14 having anadjacent pilot burner 49 inwater heater 2 withcombustion chamber 15, including agas inlet 120 for connection to a supply (not shown) of combustible gas.Valve 48 has agas outlet 124 for connection to a conduit (not shown) leading tomain burner 14 and anoutlet 126 to connect topilot burner 49. Internal components of the valve include an orifice orconduit 127 for gas flow between theinlet 120 andoutlet 124 and aclosure 154 normally resiliently biased to close the orifice to prevent or permit flow of gas from theinlet 120 to theoutlet 124 as required. - Incorporated in
valve 48 is anelectrical circuit 128 such as shown in FIG. 15, includingthermocouple 51 connected to asolenoid 132.Thermocouple 51 provides an electrical potential, sometimes hereinafter referred to as “signal,” when heated by a flame established atpilot burner 49, typically 12 to 15 mV, to solenoid 132 which is sufficient to maintainsolenoid 132 open against the normally closing bias of aspring 156 associated withclosure 154. Specifically, the electrical potential is provided tosolenoid 32, creating a magnetic force which, via an armature connected toclosure 154, maintainsclosure 154 open. It should be noted that the electrical potential is not sufficient to openclosure 154 from its closed position except whenvalve passage 127 is first opened bymanual switch 142 being manually positioned in the “pilot” or “on” positions and the potential is adequate to maintainclosure 154 in its open position. - When a flame is absent at
pilot burner 49,valve 48 remains shut except during a start up procedure. The circuit has amanual switch 142 with three positions, “off”, “pilot” and “on”. In the “pilot” position the switch may be depressed to holdopen valve 48 whilethermocouple 51 heats sufficiently topower circuit 128.Manual switch 142 is depressed in the “pilot” and “on” on positions to liftclosure 154 off its seat against the closing bias force ofspring 156. In the open position, an electrical current passing through the coil ofsolenoid 158 generated by thethermocouple 51 when heated by the flame of the pilot burner 49 (FIG. 4) is adequate to maintainclosure 154 in the open position during normal use ofwater heater 2. Normal use ofwater heater 2 involvespilot burner 49 being alight at all times. - An over-temperature energy cut out144 is installed inside a temperature sensitive thermostat probe 146 (shown in FIG. 12) which interrupts all gas flow through the valve in the event that an unsafe temperature develops inside the tank.
- As best seen in FIGS. 11 and 15,
valve 48 has afuse 134 connected inelectrical circuit 128 and exposed at the bottom surface ofvalve 48 to be sensitive to extraneous sources of flame and heat external to and in the region of the valve, particularly underneath it. -
Valve 48 features an externallyaccessible socket 136 inelectrical circuit 128 in whichthermal fuse 134 is removably inserted.Socket 136 is positioned to receivethermal fuse 134 independently and separate fromthermocouple 51. -
Socket 136 and fuse 134 are accessible from the underside ofvalve 48 as shown in FIGS. 11 and 14 whereinvalve 48 is mounted on an external vertical wall ofwater heater 2. This leads to the advantage of rapid response time since the underside is most likely to be impinged upon by extraneous flame becausevalve 48 is also vertically aboveaccess point 138 tomain burner 14 andpilot burner 49 such as for lighting, inspection and combustion air entry. Extraneous flame and heat withinwater heater 2 may result from accidental combustion of a flammable substance nearwater heater 2, the flame being likely to establish itself firstly adjacent to accesspoint 138. - Another advantage of mounting
fuse 134 to be accessible at a downward facing surface ofvalve 48 is thatfuse 134 would not be as noticeable upon a casual inspection ofwater heater 2 andvalve 48 and, therefore, not so likely to invite removal by personnel unaware of its safety-motivated purpose.Water heater 2 will not continue to function if it were removed and not replaced. - Despite the preferred downward facing position of
fuse 134, positions on other faces ofvalve 48 are possible. Fuse 134 has minimal thermal inertia and to that end involves minimal mass and is not enclosed in a copper or similar sheath. Apreferred fuse 134 is one encapsulated only in a small quantity of organic polymer resin. One presently preferred form ofthermal fuse 134 is manufactured by Therm-O-Disc, Inc., Mansfield, Ohio, USA. The radial lead type is the most suitable for insertion into asocket 136 and a model available with a maximum rated opening temperature of 102° C. has a suitably rapid response time. - Whilst the above embodiments are directed to room or indoor installed gas water heaters, the improvements described will function in an outdoor environment, if spillages occur nearby and fumes enter the gas water heater.
- The foregoing describes embodiments of the present invention and variations thereof and modification by those skilled in the art can be made thereto without departing from the scope of the invention. For example, the flame trap may be located at various positions other than those shown in the drawings and described above. One alternative position is in the side of the combustion chamber opposite the gas supply. In such a construction the flame trap would be located in an opening in the skirt below the water tank and extending through the corresponding portion of insulation.
- In a further construction the flame trap is positioned above the height of entry to the combustion chamber and the flame sensitive switch is positioned above that height of entry in the flow path of combustion air toward the burner. The aperture covered by the flame trap is in radiant heat communication with a flame sensitive switch also positioned to be sensitive to flame roll out from flue blockage or combustion air starvation.
- It is also possible that
tube 70 as shown in FIG. 9 can be made either partially or completely from flame trap materials, especially the upper portion. - Further, the flame trap may be made from a variety of materials such as those described above, but can be fabricated from others not specifically identified so long as they permit passage of air and fumes in one direction but prevent flames from travelling in the opposite direction.
- Suitable flame trap materials include those being porous, gas permeable and possessing sufficiently high thermal capacity to quench flame under typical conditions of use. Metallic structures having small holes, made from, for example, mild steel, stainless steel, copper or aluminum are suitable and porous ceramics including glass or mineral wool woven or non-woven constructions are also suitable. Fibre matrix ceramic is suitable as is flexible or rigid constructions.
- Also, the air passage for combustion air, such as in the structure labelled22 in FIG. 1, can be located between
water tank 6 andjacket 4. The passageway can be of a variety of shapes and sizes and can be formed in and bounded by the insulation or can be formed by tubes, pipes conduits and the like. - It should also be understood that utilization of the flame sensitive switch or similar devices may be used with all types of gas fired water heaters, including those not equipped with flame traps. Further, devices other than
thermocouples 51 providing electrical potentials may be employed so long as they are capable of converting heat energy to assist in actuatingclosure 154. Heat to mechanical, heat to optical, heat to magnetic and the like types of conversions are all within the scope of the invention. Accordingly, “signal” as used in the claims refers not only to “electrical potential” but to any means wherebyclosure 154 is actuated/deactuated as a result of detection of heat energy. - Finally,
main burner 14 andcombustion chamber 15 can have different constructions such as those described in U.S. Pat. Nos. 4,924,816; 5,240,411; 5,355,841; and co-pending applications 08/333,871 and 08/113,618, for example, the subject matter of which is incorporated herein by reference.
Claims (21)
1. A control valve for supplying fuel to a water heater containing a main burner and a pilot burner comprising:
a fuel inlet adapted to connect to a supply of fuel;
at least one fuel outlet adapted to connect to the main burner;
a conduit for fuel flow between the inlet and outlet;
a closure associated with the conduit to control flow of fuel from the inlet to the outlet;
a circuit associated with the valve and including a thermally actuated device associated with the closure, said device, when heated by the pilot burner providing a signal to the closure to open or close the closure; and
a combustion sensitive fuse connected to the circuit and positioned to be exposed to extraneous sources of flame and/or heat external to and adjacent the control valve.
2. The control valve defined in claim 1 further comprising an externally accessible socket in the circuit into which the fuse is removably insertable.
3. The control valve defined in claim 2 wherein the socket is adapted to receive the fuse independently separate from the thermally actuated device.
4. The control valve defined in claim 2 wherein the socket is accessible from an underside of the valve.
5. The control valve defined in claim 1 wherein the fuse is positioned at an underside of the valve.
6. The control valve defined in claim 1 wherein the closure comprises a member located in a portion of the conduit and is normally resiliently biased in a closed position.
7. The control valve defined in claim 1 wherein the circuit further comprises a solenoid associated with the closure, the solenoid being capable of receiving an electrical signal from the thermally actuated device and opening said closure in response.
8. The control valve defined in claim 1 wherein the fuse is temperature sensitive.
9. The control valve defined in claim 1 wherein the circuit further comprises an over temperature energy cut out switch associated with a temperature sensitive thermostat probe, said energy cut out switch being capable of interrupting gas flow through said control valve to the main burner and the pilot burner.
10. The control valve defined in claim 1 wherein the thermally actuated device is a thermocouple.
11. The control valve defined in claim 1 wherein the circuit further comprises a manual switch connected to the thermally actuated device and having on, off and pilot positions, said pilot position causing the closure to open until such time as the thermally actuated device is capable of providing a signal to open the closure.
12. A control valve for supplying fuel to a water heater containing a main burner and a pilot burner comprising:
a fuel inlet adapted to connect to a supply of fuel;
at least one fuel outlet adapted to connect to the main burner;
a conduit for fuel flow between the inlet and outlet;
a closure associated with the conduit to control flow of fuel from the inlet to the outlet, said closure comprising a member located in a portion of the conduit and which is normally resiliently biased in a closed position; and
a circuit associated with the valve comprising
a thermocouple associated with the closure, said thermocouple, when heated by the pilot burner providing a signal;
a solenoid associated with the closure, the solenoid being capable of receiving output from the thermocouple and maintaining open said closure in response to output indicative of a flame at said pilot burner;
an energy cut out switch associated with a temperature sensitive thermostat, the energy cut out switch being associated with a temperature sensitive thermostat probe, said energy cut out switch being capable of interrupting gas flow through said control valve to the main burner and the pilot burner; and
a combustion sensitive fuse positioned to be exposed to extraneous sources of flame and/or heat external to and adjacent the control valve.
13. A water heater comprising:
a water container having an inlet and an outlet;
a main burner positioned to heat water in the water container;
a pilot burner positioned to supply flame to the main burner; and
a control valve to supply fuel to the main and pilot burners, said control valve comprising:
a fuel inlet adapted to connect to a supply of fuel;
at least one fuel outlet adapted to connect to the main burner;
a conduit for fuel flow between the inlet and outlet;
a closure associated with the conduit to control flow of fuel from the inlet to the outlet;
a circuit associated with the valve and including a thermally actuated device associated with the closure, said device, when heated by the pilot burner providing a signal to means associated with the closure to maintain open the already opened closure or to release it to a closed position; and
a combustion sensitive fuse connected to the circuit and positioned to be exposed to extraneous sources of flame and/or heat external to and adjacent the control valve.
14. A water heater comprising:
a water container;
a combustion chamber located adjacent said tank;
a main burner and a pilot burner located inside said combustion chamber; and
a flame trap positioned at an opening in said combustion chamber, said flame trap permitting ingress of air and extraneous gases, if present, into said combustion chamber and prevent egress of flames from said structure, said flame trap being positioned below and adjacent said pilot burner.
15. The water heater defined in claim 14 further comprising a venturi extending into said combustion chamber to supply combustion air to said main burner.
16. The water heater defined in claim 14 further comprising a lint trap positioned exteriorly of said flame trap and across said opening.
17. The water heater defined in claim 14 further comprising a blocking plate positioned within said combustion chamber and adjacent said opening.
18. A water heater comprising:
a water container;
a combustion chamber located adjacent said tank, said combustion chamber having a floor portion with an opening;
a conduit extending upwardly from and being substantially sealed to said opening;
a burner located inside said combustion chamber; and
a flame trap positioned across said conduit, said flame trap permitting ingress of air and extraneous gases, if present, into said combustion chamber and prevent egress of flames from said structure.
19. The water heater defined in claim 18 further comprising a lint trap positioned exteriorly of said flame trap and across an upper portion of said conduit.
20. The water heater defined in claim 18 further comprising a lint trap positioned across said opening.
21. The water heater defined in claim 18 further comprising a blocking plate positioned within said combustion chamber and adjacent an upper portion of said conduit.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/145,312 US20020134320A1 (en) | 1995-04-04 | 2002-05-13 | Ignition inhibiting gas water heater and controller |
US10/405,203 US20030188699A1 (en) | 1995-04-04 | 2003-04-02 | Ignition inhibiting gas water heater and controller |
Applications Claiming Priority (9)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPN2136 | 1995-04-04 | ||
AUPN2136A AUPN213695A0 (en) | 1995-04-04 | 1995-04-04 | Improved gas water heating system |
AUPN5591 | 1995-09-22 | ||
AUPN5591A AUPN559195A0 (en) | 1995-09-22 | 1995-09-22 | Improved gas water heating system |
US08/626,844 US5797355A (en) | 1995-04-04 | 1996-04-03 | Ignition inhibiting gas water heater |
AUPO0786 | 1996-07-02 | ||
AUPO0786A AUPO078696A0 (en) | 1996-07-02 | 1996-07-02 | A gas control with short response time over-temperature fuse |
US74258796A | 1996-10-28 | 1996-10-28 | |
US10/145,312 US20020134320A1 (en) | 1995-04-04 | 2002-05-13 | Ignition inhibiting gas water heater and controller |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US74258796A Continuation | 1995-04-04 | 1996-10-28 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/405,203 Continuation US20030188699A1 (en) | 1995-04-04 | 2003-04-02 | Ignition inhibiting gas water heater and controller |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020134320A1 true US20020134320A1 (en) | 2002-09-26 |
Family
ID=27507447
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/145,312 Abandoned US20020134320A1 (en) | 1995-04-04 | 2002-05-13 | Ignition inhibiting gas water heater and controller |
US10/405,203 Abandoned US20030188699A1 (en) | 1995-04-04 | 2003-04-02 | Ignition inhibiting gas water heater and controller |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/405,203 Abandoned US20030188699A1 (en) | 1995-04-04 | 2003-04-02 | Ignition inhibiting gas water heater and controller |
Country Status (1)
Country | Link |
---|---|
US (2) | US20020134320A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6622661B1 (en) | 2003-01-16 | 2003-09-23 | The Water Heater Industry Joint Research And Development Consortium | Fuel-fired heating appliance with dilution air/flammable vapor bypass tube and elevated combustion air inlet |
US20060275720A1 (en) * | 2005-06-02 | 2006-12-07 | Hotton Bruce A | Low power control system and associated methods for a water heater with flammable vapor sensor |
US20080256821A1 (en) * | 2007-04-19 | 2008-10-23 | Jordan Janice A | Disposable lint catcher for electric or gas clothes dryers |
US20130042822A1 (en) * | 2011-08-18 | 2013-02-21 | Aerco International, Inc. | Water heating system with oxygen sensor |
US20130074786A1 (en) * | 2011-09-26 | 2013-03-28 | Claude Lesage | Gas water heater with increased thermal efficiency and safety |
US10330052B2 (en) * | 2017-06-29 | 2019-06-25 | Rheem Manufacturing Company | Low nitrogen oxide emission water heater |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7028642B2 (en) * | 2004-09-03 | 2006-04-18 | Rheem Manufacturing Company | Water heater having raw fuel jet pilot and associated burner clogging detection apparatus |
US7387089B2 (en) * | 2004-09-03 | 2008-06-17 | Rheem Manufacturing Company | Water heater with cross-sectionally elongated raw fuel jet pilot orifice |
US7162980B2 (en) * | 2004-11-18 | 2007-01-16 | Rheem Manufacturing Company | Water heater burner clogging detection and shutdown system |
US20070039568A1 (en) * | 2004-11-18 | 2007-02-22 | Rheem Manufacturing Company | Water Heater Burner Clogging Detection and Shutdown System with Associated Burner Apparatus |
US7261061B2 (en) * | 2004-12-03 | 2007-08-28 | American Water Heater Company | Water heater with lint collection detection |
US20110277706A1 (en) * | 2010-05-13 | 2011-11-17 | Arnold J Eric | Gas-fired heating device having a thermopile |
-
2002
- 2002-05-13 US US10/145,312 patent/US20020134320A1/en not_active Abandoned
-
2003
- 2003-04-02 US US10/405,203 patent/US20030188699A1/en not_active Abandoned
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6622661B1 (en) | 2003-01-16 | 2003-09-23 | The Water Heater Industry Joint Research And Development Consortium | Fuel-fired heating appliance with dilution air/flammable vapor bypass tube and elevated combustion air inlet |
US20060275720A1 (en) * | 2005-06-02 | 2006-12-07 | Hotton Bruce A | Low power control system and associated methods for a water heater with flammable vapor sensor |
US20080256821A1 (en) * | 2007-04-19 | 2008-10-23 | Jordan Janice A | Disposable lint catcher for electric or gas clothes dryers |
US20130042822A1 (en) * | 2011-08-18 | 2013-02-21 | Aerco International, Inc. | Water heating system with oxygen sensor |
US9175853B2 (en) * | 2011-08-18 | 2015-11-03 | Aerco International, Inc. | Water heating system with oxygen sensor |
US20130074786A1 (en) * | 2011-09-26 | 2013-03-28 | Claude Lesage | Gas water heater with increased thermal efficiency and safety |
US10330052B2 (en) * | 2017-06-29 | 2019-06-25 | Rheem Manufacturing Company | Low nitrogen oxide emission water heater |
Also Published As
Publication number | Publication date |
---|---|
US20030188699A1 (en) | 2003-10-09 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6418883B2 (en) | Ignition inhibiting gas water heater | |
US6003477A (en) | Ignition inhibiting gas water heater | |
US6295951B1 (en) | Ignition inhibiting gas water heater | |
CA2286504C (en) | Power vented water heater with air inlet | |
US6082310A (en) | Air inlets for water heaters | |
US6401668B2 (en) | Ignition inhibiting gas water heater | |
US20020134320A1 (en) | Ignition inhibiting gas water heater and controller | |
CA2528814A1 (en) | Water heater with lint collection detection | |
US6540504B2 (en) | Combustion appliance with flame blocking device | |
US6662757B2 (en) | Explosion proof gas-fired water heater | |
US6269779B2 (en) | Sealed access assembly for water heaters | |
US20020134322A1 (en) | Gas fired appliance safety device | |
US6302062B2 (en) | Sealed access assembly for water heaters | |
US6116195A (en) | Flame traps for water heaters | |
US7438023B2 (en) | Heating device having a thermal cut-off circuit for a fuel line and method of operating the same | |
CA2338078C (en) | Air inlets for gas water heaters | |
CA2556242A1 (en) | Gas heating device control | |
MXPA04008565A (en) | Fuel-fired water heater with dual function combustion cutoff switch in its draft structure. | |
US6085700A (en) | Heat sensitive air inlets for water heaters | |
US6446581B1 (en) | Flammable vapor resistant water heater with low NOx emissions | |
CA2565058C (en) | Air inlets for gas water heaters | |
US6443103B1 (en) | Flammable vapor resistant water heater with low NOx emissions | |
CA2280613C (en) | Water heater with heat sensitive air inlet | |
CA2401470C (en) | Explosion proof gas-fired water heater |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: FLAME GUARD WATER HEATERS, INC., GEORGIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SRP 687 PTY LTD.;REEL/FRAME:013774/0264 Effective date: 20030120 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |