EP1122498A2 - Gas appliances and control systems - Google Patents
Gas appliances and control systems Download PDFInfo
- Publication number
- EP1122498A2 EP1122498A2 EP01300583A EP01300583A EP1122498A2 EP 1122498 A2 EP1122498 A2 EP 1122498A2 EP 01300583 A EP01300583 A EP 01300583A EP 01300583 A EP01300583 A EP 01300583A EP 1122498 A2 EP1122498 A2 EP 1122498A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- blower
- gas
- thermistor
- flow
- enclosure
- 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.)
- Withdrawn
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/06—Regulating fuel supply conjointly with draught
- F23N1/062—Regulating fuel supply conjointly with draught using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/14—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors
- F23N5/143—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
- F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
- F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/08—Microprocessor; Microcomputer
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/10—Fail safe for component failures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/26—Fail safe for clogging air inlet
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2233/00—Ventilators
- F23N2233/02—Ventilators in stacks
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/12—Fuel valves
- F23N2235/14—Fuel valves electromagnetically operated
Definitions
- This invention relates to gas appliances of the kind including a gas burner, a blower for causing flow of air and combustion products in the appliance and a detector for detecting inadequate flow through the appliance.
- Gas appliances such as gas boilers, include various safety features and often have some means for ensuring that gas supply does not continue if air supply to the appliance is inadequate for correct combustion.
- a pressure sensor detects the pressure at the blower outlet. In this way, any failure of the blower or blockage to flow of air or combustion products can be detected.
- the problem with this previous arrangement is that the pressure sensors are relatively expensive, especially those needed to detect low air pressures. They can also be unreliable leading to unsatisfactory combustion or unnecessary boiler shut-down.
- multiple pressure sensors are needed in boilers having an output that can be modulated.
- a gas appliance of the above-specified kind characterised in that the detector includes a thermal sensor responsive to flow caused by the blower.
- the thermal sensor preferably includes a temperature-dependent electrical device, such as resistor or thermistor.
- the appliance includes two temperature-dependent electrical devices, the first of which is exposed to flow caused by the blower and the second of which is protected from such flow such that operation of the blower causes different changes in the first and second devices.
- the appliance is preferably a boiler having a heat exchanger located in an enclosure between the burner and the inlet of the blower, the thermal sensor being responsive to gas flow along a passage opening into the enclosure.
- the enclosure is preferably contained within an outer housing, the outlet of the blower opening to an exhaust passage of a balanced flue and an inlet passage of the balanced flue opening into the housing outside the enclosure.
- a gas boiler including a burner 1 connected to a gas supply pipe 2 via a gas valve 3.
- a heat exchanger 4 mounted above the burner 1 transfers heat produced by the burner to water or ventilation air.
- the boiler also includes an induced draught blower 5 having its inlet located above the heat exchanger 4 and its outlet coupled to the central, exhaust passage 6 along a balanced flue 7.
- the casing 8 of the boiler is sealed and opens into the outer, inlet passage 9 of the flue 7 so that, when the blower 5 operates it extracts combustion products from the boiler to the exhaust passage 6 of the flue and induces a draught of air along the outer, inlet passage of the flue to the burner 1 in order to enable combustion.
- An inner enclosure 80 extends between the burner 1, heat exchanger 4 and blower 5 to control flow of air and combustion products from the burner to the blower inlet.
- the boiler is conventional.
- the boiler also includes a control system 10 having an output on line 11 to the gas valve 3, to control its operation.
- the control system 10 is shown in greater detail in Figure 2 and comprises a flow-sensing detector unit 20 and a boiler logic unit 30.
- the flow-sensing unit 20 includes two negative temperature coefficient thermistors 12 and 13, or other temperature-responsive resistors, connected in series across a voltage source 14. A series of two further fixed resistors 15 and 16 is also connected across the voltage source 14, in parallel with the two thermistors 12 and 13.
- the sensing unit 20 includes a comparator 17 having one input 18 connected to the junction 19 between the two thermistors 12 and 13 and its other input 21 connected to the junction 22 between the two fixed resistors 15 and 16.
- the output 23 of the comparator 17 is connected to one input of the logic unit 30 and is also connected with the positive terminal of the voltage source 14 via a further resistor 24.
- the logic unit 30 has several further inputs 25 from other conventional safety sensors, such as a spark sensor 26 and provides the output on line 11 to open the gas valve 3 when all its inputs indicate that it is appropriate to supply gas to the burner 1.
- the two thermistors 12 and 13 are mounted adjacent to one another in a block 50 of metal or plastics located in an opening of the inner enclosure 80 adjacent the blower 5.
- One thermistor 12 is located in a channel 51 that opens at opposite ends of the block 50 so that one end is at the blower inlet pressure and the opposite end is at the (higher) ambient pressure within the casing 8, which is the pressure at the air inlet of the burner 1. There is, therefore, a pressure differential along the channel 51 causing air to flow down along the channel, over the thermistor 12.
- the other thermistor 13 is located in a second channel 52 through the block 50, which is blocked so that it is not exposed to any air flow.
- the blower 5 does not operate or if there is some restriction to flow through the exhaust 6 or inlet passage 9 of the flue 7, the flow over the exposed thermistor 12 will fall and its temperature will rise closer to that of the concealed thermistor 13.
- the voltage at the junction 19 between the thermistors will, therefore, rise to approximately half that across the series pair of the two thermistors.
- the comparator 17 is arranged so that its output causes the logic unit 30 to maintain the gas valve 3 off in such a condition.
- the present invention provides effective monitoring in a gas appliance of both air flow to a burner and the flow of combustion products from a burner without the need for a pressure sensor. It will be appreciated that the invention is not confined to gas boilers but could be used in other gas appliances. Other thermal means responsive to air flow could be used instead of thermistors.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Combustion (AREA)
- Regulation And Control Of Combustion (AREA)
Abstract
Description
- This invention relates to gas appliances of the kind including a gas burner, a blower for causing flow of air and combustion products in the appliance and a detector for detecting inadequate flow through the appliance.
- Gas appliances, such as gas boilers, include various safety features and often have some means for ensuring that gas supply does not continue if air supply to the appliance is inadequate for correct combustion. In gas boilers, where a blower is used to deliver air to the burner, a pressure sensor detects the pressure at the blower outlet. In this way, any failure of the blower or blockage to flow of air or combustion products can be detected. The problem with this previous arrangement is that the pressure sensors are relatively expensive, especially those needed to detect low air pressures. They can also be unreliable leading to unsatisfactory combustion or unnecessary boiler shut-down. Furthermore, multiple pressure sensors are needed in boilers having an output that can be modulated.
- It is an object of the present invention to provide an alternative gas appliance and control system for a gas appliance.
- According to the present invention there is provided a gas appliance of the above-specified kind, characterised in that the detector includes a thermal sensor responsive to flow caused by the blower.
- The thermal sensor preferably includes a temperature-dependent electrical device, such as resistor or thermistor. Preferably, the appliance includes two temperature-dependent electrical devices, the first of which is exposed to flow caused by the blower and the second of which is protected from such flow such that operation of the blower causes different changes in the first and second devices. The appliance is preferably a boiler having a heat exchanger located in an enclosure between the burner and the inlet of the blower, the thermal sensor being responsive to gas flow along a passage opening into the enclosure. The enclosure is preferably contained within an outer housing, the outlet of the blower opening to an exhaust passage of a balanced flue and an inlet passage of the balanced flue opening into the housing outside the enclosure.
- A gas boiler appliance including a control system according to the present invention, will now be described, by way of example, with reference to the accompanying drawing, in which:
- Figure 1 shows the boiler schematically; and
- Figure 2 shows the control system in greater detail.
-
- With reference first to Figure 1 there is shown a gas boiler including a
burner 1 connected to agas supply pipe 2 via agas valve 3. Aheat exchanger 4 mounted above theburner 1 transfers heat produced by the burner to water or ventilation air. The boiler also includes an induced draught blower 5 having its inlet located above theheat exchanger 4 and its outlet coupled to the central, exhaust passage 6 along a balanced flue 7. Thecasing 8 of the boiler is sealed and opens into the outer,inlet passage 9 of the flue 7 so that, when the blower 5 operates it extracts combustion products from the boiler to the exhaust passage 6 of the flue and induces a draught of air along the outer, inlet passage of the flue to theburner 1 in order to enable combustion. Aninner enclosure 80 extends between theburner 1,heat exchanger 4 and blower 5 to control flow of air and combustion products from the burner to the blower inlet. As so far described, the boiler is conventional. - The boiler also includes a
control system 10 having an output online 11 to thegas valve 3, to control its operation. Thecontrol system 10 is shown in greater detail in Figure 2 and comprises a flow-sensing detector unit 20 and aboiler logic unit 30. The flow-sensing unit 20 includes two negativetemperature coefficient thermistors voltage source 14. A series of two furtherfixed resistors voltage source 14, in parallel with the twothermistors sensing unit 20 includes acomparator 17 having oneinput 18 connected to thejunction 19 between the twothermistors other input 21 connected to thejunction 22 between the twofixed resistors output 23 of thecomparator 17 is connected to one input of thelogic unit 30 and is also connected with the positive terminal of thevoltage source 14 via afurther resistor 24. Thelogic unit 30 has severalfurther inputs 25 from other conventional safety sensors, such as a spark sensor 26 and provides the output online 11 to open thegas valve 3 when all its inputs indicate that it is appropriate to supply gas to theburner 1. - The two
thermistors block 50 of metal or plastics located in an opening of theinner enclosure 80 adjacent the blower 5. Onethermistor 12 is located in achannel 51 that opens at opposite ends of theblock 50 so that one end is at the blower inlet pressure and the opposite end is at the (higher) ambient pressure within thecasing 8, which is the pressure at the air inlet of theburner 1. There is, therefore, a pressure differential along thechannel 51 causing air to flow down along the channel, over thethermistor 12. Theother thermistor 13 is located in asecond channel 52 through theblock 50, which is blocked so that it is not exposed to any air flow. - When the blower 5 is operating and there is no impediment to the flow of air or combustion products through the boiler, air will flow through the
channel 51 over thefirst thermistor 12 in thechannel 51 but not over thesecond thermistor 13 in the blockedchannel 52. Since boththermistors thermistor 12 will increase the rate of dissipation of heat from it but will have no effect on theother thermistor 13. The temperature of the exposedthermistor 12 will, therefore, fall below that of theother thermistor 13 and its resistance will increase, causing the voltage atjunction 19 to fall. If flow is sufficient, this voltage is low enough to cause thecomparator 17 to produce and output to an input to thelogic unit 30 enabling it to hold open thegas valve 3, providing its other inputs are also appropriate. - If the blower 5 does not operate or if there is some restriction to flow through the exhaust 6 or
inlet passage 9 of the flue 7, the flow over the exposedthermistor 12 will fall and its temperature will rise closer to that of theconcealed thermistor 13. The voltage at thejunction 19 between the thermistors will, therefore, rise to approximately half that across the series pair of the two thermistors. Thecomparator 17 is arranged so that its output causes thelogic unit 30 to maintain thegas valve 3 off in such a condition. - The present invention provides effective monitoring in a gas appliance of both air flow to a burner and the flow of combustion products from a burner without the need for a pressure sensor. It will be appreciated that the invention is not confined to gas boilers but could be used in other gas appliances. Other thermal means responsive to air flow could be used instead of thermistors.
Claims (6)
- A gas appliance including a gas burner (1), a blower (5) for causing flow of air and combustion products in the appliance and a detector (20) for detecting inadequate flow through the appliance, characterised in that the detector (20) includes a thermal sensor (12, 13) responsive to flow caused by the blower (5).
- A gas appliance according to Claim 1, characterised in that the thermal sensor includes a temperature-dependent electrical device (12, 13).
- A gas appliance according to Claim 2, characterised in that the electrical device is a resistor or thermistor (12, 13).
- A gas appliance according to Claim 2 or 3, characterised in that the appliance includes two temperature-dependent electrical devices (12 and 13), the first of which (12) is exposed to flow caused by the blower (5) and the second of which (13) is protected from such flow such that operation of the blower (5) causes different changes in the first and second devices (12 and 13).
- A gas appliance according to any one of the preceding claims, characterised in that the appliance is a boiler having a heat exchanger (4) located in an enclosure (80) between the burner (1) and the inlet of the blower (5), and that the thermal sensor (12, 13) is responsive to gas flow along a passage (51) opening into the enclosure (80).
- A gas appliance according to Claim 5, characterised in that the enclosure (80) is contained within an outer housing (8), that the outlet of the blower (5) opens to an exhaust passage (6) of a balanced flue (7), and that an inlet passage (9) of the balanced flue (7) opens into the housing (8) outside the enclosure (80).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0002263 | 2000-02-02 | ||
GBGB0002263.2A GB0002263D0 (en) | 2000-02-02 | 2000-02-02 | Gas appliances and control systems |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1122498A2 true EP1122498A2 (en) | 2001-08-08 |
EP1122498A3 EP1122498A3 (en) | 2004-01-21 |
Family
ID=9884730
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01300583A Withdrawn EP1122498A3 (en) | 2000-02-02 | 2001-01-23 | Gas appliances and control systems |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP1122498A3 (en) |
GB (2) | GB0002263D0 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6766771B1 (en) | 2003-09-11 | 2004-07-27 | The Water Heater Industry Joint Research And Development Consortium | Fuel-fired water heater with dual function combustion cutoff switch in its draft structure |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106524219A (en) * | 2016-12-19 | 2017-03-22 | 大连圣鼎工业装备有限公司 | Environment-friendly automatic control low-index emission gas boiler unit |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0087539A1 (en) * | 1982-03-03 | 1983-09-07 | E.L.M. Leblanc, Société dite: | Furnaces with mechanical extraction |
JPS6284224A (en) * | 1985-10-09 | 1987-04-17 | Youei Seisakusho:Kk | Hot water heater |
US4951651A (en) * | 1989-09-28 | 1990-08-28 | Rheem Manufacturing Company | Vent overpressurization detection system for a fuel-fired, induced draft furnace |
DE9210862U1 (en) * | 1991-08-16 | 1992-10-15 | Joh. Vaillant Gmbh U. Co, 5630 Remscheid | Heating device |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4629113A (en) * | 1984-10-05 | 1986-12-16 | Rhr, Inc. | Furnace controller |
US4792089A (en) * | 1985-11-26 | 1988-12-20 | Carrier Corporation | Self-correcting microprocessor control system and method for a furnace |
KR900006243B1 (en) * | 1986-10-16 | 1990-08-27 | 린나이 가부시기가이샤 | Burner apparatus |
AT401569B (en) * | 1991-12-12 | 1996-10-25 | Vaillant Gmbh | HEATING DEVICE |
US5865611A (en) * | 1996-10-09 | 1999-02-02 | Rheem Manufacturing Company | Fuel-fired modulating furnace calibration apparatus and methods |
-
2000
- 2000-02-02 GB GBGB0002263.2A patent/GB0002263D0/en not_active Ceased
-
2001
- 2001-01-23 EP EP01300583A patent/EP1122498A3/en not_active Withdrawn
- 2001-01-25 GB GB0102221A patent/GB2358915A/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0087539A1 (en) * | 1982-03-03 | 1983-09-07 | E.L.M. Leblanc, Société dite: | Furnaces with mechanical extraction |
JPS6284224A (en) * | 1985-10-09 | 1987-04-17 | Youei Seisakusho:Kk | Hot water heater |
US4951651A (en) * | 1989-09-28 | 1990-08-28 | Rheem Manufacturing Company | Vent overpressurization detection system for a fuel-fired, induced draft furnace |
DE9210862U1 (en) * | 1991-08-16 | 1992-10-15 | Joh. Vaillant Gmbh U. Co, 5630 Remscheid | Heating device |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 0112, no. 89 (M-625), 18 September 1987 (1987-09-18) -& JP 62 084224 A (YOUEI SEISAKUSHO:KK), 17 April 1987 (1987-04-17) * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6766771B1 (en) | 2003-09-11 | 2004-07-27 | The Water Heater Industry Joint Research And Development Consortium | Fuel-fired water heater with dual function combustion cutoff switch in its draft structure |
Also Published As
Publication number | Publication date |
---|---|
GB2358915A (en) | 2001-08-08 |
GB0002263D0 (en) | 2000-03-22 |
GB0102221D0 (en) | 2001-03-14 |
EP1122498A3 (en) | 2004-01-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4708636A (en) | Flow sensor furnace control | |
CA2021001C (en) | Home heating system draft controller | |
US7250870B1 (en) | Back draft alarm assembly for combustion heating device | |
US5158446A (en) | Combination pressure and temperature limit control for a fuel-fired, forced draft heating appliance combustion product exhaust system | |
US8002199B2 (en) | Highly sensitive airflow direction sensing | |
CA2003799A1 (en) | Vent overpressurization detection system for a fuel-fired induced draft furnace | |
US4449569A (en) | Method and apparatus for regulating fluid flows in parallel-connected conduits (e.g. in furnace installations having air preheaters and by-pass conduits) | |
EP1122498A2 (en) | Gas appliances and control systems | |
GB2237665A (en) | Boiler control | |
US5143050A (en) | Water heater heat rollout sensor | |
US4113005A (en) | Waste heat boiler temperature control system | |
JP3777041B2 (en) | Combustion equipment | |
US6748163B2 (en) | Electric heater with dual overheat limits | |
ATE209319T1 (en) | BURNER SYSTEM | |
US10533771B2 (en) | Blower assembly with compensation for vent back pressure | |
GB2105888A (en) | Detecting flue blockage | |
GB2076574A (en) | Fuel-heated Heat Source | |
KR100862180B1 (en) | Automatic apparatus for shutting off the supply of gas | |
EP0036236A1 (en) | Heating device | |
JP3244995B2 (en) | Gas water heater with combustion abnormality detection function | |
JP3030167B2 (en) | Water heater combustion control device | |
JP2982063B2 (en) | Combustion control device | |
JP3569583B2 (en) | Gas water heater with abnormality detection function | |
JP2875377B2 (en) | Malfunction prevention method during pilot burner combustion | |
NL8701572A (en) | CONTROL AND SAFETY UNIT FOR A HEATER. |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
AX | Request for extension of the european patent |
Extension state: AL LT LV MK RO SI |
|
18D | Application deemed to be withdrawn |
Effective date: 20030801 |