Method and controller for operating a gas burner appliance and gas burner appliance

Abstract

Method for operating a gas burner appliance ( 10 ), the gas burner appliance com-prising: a combustion chamber ( 11 ) in which a defined gas/air mixture is combusted after combustion has been started; a mixing device ( 25 ) to provide said gas/air mixture by mixing an air flow provided by an air duct ( 15 ) with a gas flow provided by a gas duct ( 16 ); a fan ( 14 ) to provide the air flow or the flow of the gas/air mixture; a gas safety valve unit ( 19 ) assigned to the gas duct to open or close the gas duct; a gas flow modulator ( 18 ) or a gas flow regulator ( 28 ) assigned to the gas duct to keep a mixing ratio of the defined gas/air mixture constant over the modulation range of the gas burner appliance; an absolute pressure sensor ( 21 ) positioned between the gas safety valve unit and the mixing device, wherein the gas burner appliance is operated to determine the air flow resistance of the same by executing the following steps before combustion becomes started: Measuring a first absolute pressure by the absolute pressure sensor ( 21 ) when the gas safety valve unit ( 19 ) is closed and when the fan ( 14 ) is stopped. Measuring a second absolute pressure by the absolute pressure sensor ( 21 ) when the gas safety valve unit ( 19 ) is closed and when the fan ( 14 ) is running. Determining a pressure difference between the first absolute pressure and the second absolute pressure. Determining on basis of the pressure difference the air flow resistance of the gas burner appliance.

1 . A method for operating a gas burner appliance, the gas burner appliance comprising:
 a combustion chamber in which a defined gas/air mixture is combusted after combustion has been started in connection with a burner start,   a mixing device to provide the gas/air mixture by mixing an air flow provided by an air duct with a gas flow provided by a gas duct,   a fan to provide the air flow or the flow of the gas/air mixture, wherein a fan speed of the fan depends on a burner-load of the gas burner appliance,   a gas safety valve unit assigned to the gas duct to open or close the gas duct,   a gas flow modulator or a gas flow regulator assigned to the gas duct to keep a mixing ratio of gas and air of the defined gas/air mixture constant over the modulation range of the gas burner appliance,   an absolute pressure sensor positioned between the gas safety valve unit and the mixing device,   wherein the gas burner appliance is operated to determine the air flow resistance of the gas burner appliance by executing the following steps before combustion becomes started in connection with a burner start:
 measuring a first absolute pressure by the absolute pressure sensor is closed and when the fan is stopped, 
 measuring a second absolute pressure by the absolute pressure sensor when the gas safety valve unit is closed and when the fan is running, 
 determining a pressure difference between the first absolute pressure and the second absolute pressure, 
 determining on basis of the pressure difference the air flow resistance of the gas burner appliance. 
   
     
     
         2 . The method of  claim 1 , wherein the air flow resistance of the gas burner appliance is determined from the pressure difference on basis of a characteristic map or characteristic curve. 
     
     
         3 . The method of  claim 1 , further comprising:
 comparing the air flow resistance or the pressure difference with at least one respective threshold,   adapting operation of the gas burner appliance for the combustion of the gas/air mixture on basis of the comparison.   
     
     
         4 . The method of  claim 1 , further comprising:
 measuring an ambient temperature,   determining from the first absolute pressure and the ambient temperature an air density,   determining from the air density and the pressure difference an air mass flow.   
     
     
         5 . The method of  claim 4 , wherein the air flow resistance of the gas burner appliance is determined from the air mass flow preferably on basis of a characteristic map or characteristic curve. 
     
     
         6 . The method of  claim 4 , further comprising:
 comparing the air mass flow with at least one respective threshold,   adapting operation of the gas burner appliance for the combustion of the gas/air mixture on basis of the comparison.   
     
     
         7 . The method of  claim 3 , further comprising:
 comparing the air flow resistance with a respective first threshold and a respective second threshold, wherein:   in response to the air flow resistance being below the respective first threshold, determining a regular air flow resistance of the gas burner appliance and operating the fan at a regular nominal fan speed,   in response to the air flow resistance being above the respective first threshold and below the respective second threshold, determining a permissible increased air flow resistance of the gas burner appliance and operating the fan at an increased nominal fan speed,   in response to the air flow resistance being above the respective second threshold, determining an impermissible increased air flow resistance of the gas burner appliance and generating a warning message and/or stopping operation of the gas burner appliance.   
     
     
         8 . The method of  claim 3 , further comprising:
 comparing the pressure difference with a respective first threshold and a respective second threshold, wherein:
 in response to the pressure difference being above the respective first thresh old, determining a regular air flow resistance of the gas burner appliance and operating the fan at a regular nominal fan speed, 
 in response to the pressure difference being below the respective first threshold and above the respective second threshold, determining a permissible increased airflow resistance of the gas burner appliance and operating the fan at an increased nominal fan speed, 
 in response to the pressure difference being below the respective second threshold, determining an impermissible increased airflow resistance of the gas burner appliance and generating a warning message and/or stopping operation of the gas burner appliance. 
   
     
     
         9 . The method of  claim 6 , further comprising:
 comparing the air mass flow with a respective first threshold and a respective second threshold, wherein:
 in response to the air mass flow being above the respective first threshold, determining a regular air flow resistance of the gas burner appliance and operating the fan at a regular nominal fan speed, 
 in response to the air mass flow being below the respective first threshold and above the respective second threshold, determining a permissible increased air flow resistance of the gas burner appliance and operating the fan at an increased nominal fan speed, 
 in response to the mass flow being below the respective second threshold, determining an impermissible increased air flow resistance of the gas burner appliance and generating a warning message and/or stopping operation of the gas burner appliance. 
   
     
     
         10 . The method of  claim 1 , further comprising:
 determining a reference value for the air flow resistance of the gas burner appliance by determining the air flow resistance of the gas burner appliance immediately after installation of the gas burner appliance in the field or during an initial operation of the gas burner appliance,   comparing an air flow resistance determined before combustion becomes started in connection with a burner start with the reference value, wherein:
 in response to a difference between the air flow resistance and the reference value being below a respective first threshold, determining a regular air flow resistance of the gas burner appliance at a regular nominal fan speed, 
 in response to the difference between the air flow resistance and the reference value being above the respective first threshold and below a respective second threshold, determining a permissible increased air flow resistance of the gas burner appliance at an increased nominal fan at an increased nominal fan speed, 
 in response to the difference between the air flow resistance and the reference value being above the respective second threshold, determining an impermissible increased air flow resistance of the gas burner appliance and generating warning message and/or stopping operation of the gas burner appliance. 
   
     
     
         11 . The method of  claim 1 , further comprising:
 comparing the air flow resistance determined before combustion becomes started in connection with a burner start with a factory provided reference value, wherein:
 in response to a difference between the air flow resistance and the factory provided reference value i-s-being below a respective first threshold, deter mining a regular air flow resistance of the gas burner appliance and operating the fan at a regular nominal fan speed, 
 in response to the difference between the airflow resistance and the factory provided reference value being above the respective first threshold and below a respective second threshold, determining a permissible increased air flow resistance of the gas burner appliance and operating the fan at an increased nominal fan speed, 
 in response to the difference between the airflow resistance and the factory provided reference value being above the respective second threshold, determining an impermissible increased air flow resistance of the gas burner appliance and generating warning message and/or stopping operation of the gas burner appliance. 
   
     
     
         12 . The method of  claim 7 , further comprising:
 bounding the increased nominal fan speed by a maximum fan speed preferably to prevent a blown free siphon.   
     
     
         13 . The method of  claim 1 , further comprising:
 after combustion has been started, the defined mixing ratio of gas and air or a l-value is controlled over the modulation range of the gas burner appliance using a pneumatic gas flow regulator.   
     
     
         14 . The method of  claim 1 , further comprising:
 after combustion has been started, the defined mixing ratio of gas and air or a l-value is controlled over the modulation range of the gas burner appliance using an electric gas flow modulator.   
     
     
         15 . A controller for a gas burner appliance wherein the controller is configured to operate the gas burner appliance according to the method of  claim 1 . 
     
     
         16 . A gas burner appliance comprising the controller of  claim 15 , wherein:
 the controller is configured to determine an air flow resistance of the gas burner appliance by executing the following steps before combustion becomes started in connection with a burner start:
 receive a first absolute pressure from an absolute pressure sensor of the gas burner appliance measured when a gas safety valve unit of the gas burner appliance is closed and when a fan is stopped, 
 receive a second absolute pressure from the absolute pressure sensor measured when the gas safety valve unit is closed and when the fan is running, 
 determine a pressure difference between the first absolute pressure and the second absolute pressure, 
 determine on basis of the pressure difference the air flow resistance of the gas burner appliance.