Classifications

• • 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
  • F23N1/00—Regulating fuel supply
  • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
  • F23N1/082—Regulating fuel supply conjointly with another medium, e.g. boiler water using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
  • F23N2225/18—Measuring temperature feedwater temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
  • F23N2225/19—Measuring temperature outlet temperature water heat-exchanger
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
  • F23N2225/20—Measuring temperature entrant temperature
• • 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
• • 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

Definitions

• the present invention relates to a method for monitoring the heating water circulation in a gas water heater, with a temperature sensor arranged in the heating water supply line for the flow temperature control, the flow temperature being monitored continuously, with a stored in a control device which is connected to a burner control maximum flow temperature compared and the burner is switched off when this temperature is exceeded, and on a device for performing the method.
• Low water safety devices are known for combination gas water heaters and continuous gas water heaters. Such low water safety devices have a Venturi nozzle located in the cold water line to the process water heat exchanger, from the narrow point of which a pressure measuring line leads to a membrane switch, the other pressure measuring chamber of which is also connected via a pipeline to the water line in front of the Venturi nozzle.
• the drop in pressure at the membrane allows conclusions to be drawn about the throughput of water to the heat exchanger, so that the gas supply to the burner is released after a minimum throughput has been exceeded.
• This task is solved in a method according to the introductory part by the steps that the heating water temperature is measured at a further point on or in the heat exchanger approximately in the middle between the supply and return lines, that the temperature difference ⁇ T between the pre-heating temperature T 2 and this heating water temperature T 1 is determined that this temperature difference AT is compared with a maximum temperature difference ⁇ Tmax stored in the control device and a minimum temperature difference ⁇ Tmin and that in addition to the first switch-off criterion T 2 - T 1 > ⁇ Tmax, this temperature difference ⁇ T is used as the second switch-off criterion ⁇ T ⁇ Tmin.
• the switch-off criterion ⁇ T ⁇ Tmin is suppressed for a short time during the start-up phase after the burner has started.
• the invention provides that upon the occurrence of the switch-off criterion T 2 - T 1> ⁇ Tmax, the burner is switched off by the control device for a lock period of for example 5 minutes, while the if the heat is requested, a new burner start is prevented.
• Such a shutdown could occur, for example, if the heating water circulation becomes weaker due to thermostatic valves on the radiators.
• the burner is switched off in a locking manner by the control device and an optical water deficiency warning, for example via the display, is switched on.
• a device for carrying out the method for monitoring the heating water circulation in a gas water heater consisting of at least one heat exchanger heated by a burner, to which a heating water supply line with a temperature sensor for the flow temperature control and a heating water return line, in which a heating water circulation pump is located, is connected, with a control device into which set values such as the maximum flow temperature or the like can be entered and Can be stored and which is connected by line to an automatic burner control system, is characterized in that a temperature sensor known per se, in particular an NTC sensor with a small time constant, is provided approximately in the middle between the supply and return lines, in that a subtractor arranged in the control device is provided the temperature difference between the flow temperature sensor and this heating water temperature sensor is determined and that a known comparator circuit is provided in the control device, by means of which the occurrence of both switch-off criteria AT> ⁇ Tmax and AT ⁇ Tmin can be detected and a The burner can be switched off by the burner control via the line.
• the device according to the invention enables simple and reliable monitoring of the water circulation in the heating water line.
• the installation of a second temperature sensor and the provision of the electronic components in the control device require no special effort.
• the drawing schematically shows a partially shown circulation gas water heater.
• the circulating water heater partially shown in the figure has a two-part heating water heat exchanger 2, 3 heated by a burner 1.
• a temperature sensor 5 for detecting the temperature T 1 for example an NTC sensor, is installed in a connecting line 4, which can also be a water cap or other connection of or within a one-part heat exchanger.
• a heating water return line 7 provided with a circulation pump 6 is connected to the heat exchanger part 2, and a heating water supply line 8 is connected to the heat exchanger part 3.
• a second temperature sensor 9, which can also be an NTC sensor and which monitors the flow temperature T 2 is arranged in the heating water supply line 8 at a certain distance from the heat exchanger 3.
• the burner 1 is supplied with gas via a gas line 10, in which a gas valve 11, which is controlled by a magnetic switch 12, is also supplied with an ignition device 13 and a flame detection device and connected to a burner control 14 via lines.
• the magnetic switch 12 for the gas valve 11 is also connected via a control line 16 to the automatic firing device 14, which in turn is connected to a control device 15 via control lines 21 and feedback lines 22.
• a control line 17 leads from the control device 15 to the electric motor 18 of the heating water circulating pump 6. Furthermore, the control device 15 is connected to the heating water temperature sensor 5 via a line 19 and to the flow temperature sensor 9 via a line 20.
• the control device 15, which has a circuit with a subtractor for determining the temperature difference ⁇ T T 2 - T 1 and a comparator circuit for comparing this temperature difference with a minimum temperature difference ⁇ Tmin and a maximum temperature difference ⁇ Tmax, is also equipped with a display for reporting special operating states .
• the present method or the device has been set out here on a circulation gas water heater with a divided heat exchanger. If a one-piece heat exchanger is used, the heating water temperature sensor 5 according to the invention would have to be arranged approximately in the middle between the supply and return lines, that is to say approximately in the middle of the heat exchanger.
• the first switch-off criterion namely T 2 - T 1 > ⁇ T max
• the burner 1 will be switched off.
• the previously low circulation and the residual burner heat also enable the second switch-off criterion to be achieved, but this is no longer effective in the system already shut down by the first switch-off criterion.
• the device is blocked by the control device for a period of, for example, 5 minutes, during which a burner start is prevented when heat is requested.
• the burner is shut off by the control device 15 if the temperature drops below the minimum temperature difference , issued.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
• Heat-Pump Type And Storage Water Heaters (AREA)
• Steam Or Hot-Water Central Heating Systems (AREA)
• Control Of Steam Boilers And Waste-Gas Boilers (AREA)
• Control Of Combustion (AREA)
• Control For Baths (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=3540645

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (7)

Citations (2)

Family Cites Families (2)

• 1989
  • 1989-12-12 AT AT0280989A patent/AT395776B/de active
• 1990
  • 1990-12-12 DE DE4039643A patent/DE4039643A1/de not_active Withdrawn
  • 1990-12-12 ES ES199090710036T patent/ES2036106T3/es not_active Expired - Lifetime
  • 1990-12-12 EP EP90710036A patent/EP0433215B1/fr not_active Expired - Lifetime
  • 1990-12-12 DE DE9090710036T patent/DE59000349D1/de not_active Expired - Lifetime
  • 1990-12-12 DK DK90710036.6T patent/DK0433215T3/da not_active Application Discontinuation
  • 1990-12-12 AT AT90710036T patent/ATE81398T1/de not_active IP Right Cessation
• 1992
  • 1992-11-27 GR GR920402747T patent/GR3006373T3/el unknown

Patent Citations (2)

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