Abstract: The gas-fired heating unit has an atmospheric gas burner including a mixing chamber and a burner medium covering the mixing chamber, a combustion chamber in which the atmospheric gas burner is arranged, a fuel gas/air supply system that has respective inlets for fuel gas and combustion air and an ignition device having at least one pilot flame and supply pipe for pilot flame gas associated the mixing chamber. In order to reduce NOx emissions and reduce ignition noise, the ignition device has an upwardly open mixing space arranged in the mixing chamber and immediately under the burner medium, the supply pipe for the pilot flame gas is connected to the mixing space and the mixing space is provided with an inlet for primary air.

Abstract: The gas-fired heating apparatus, especially a water heater, has a combustion chamber (2a); an atmospheric gas burner (5) within the combustion chamber (2a); a combustion gas/air supply system (18) having an intake device (16) for combustion gas and primary air to be mixed with the combustion gas, which is arranged outside of the combustion chamber, and an oscillation-damping air supply chamber (11) provided with at least one air inlet (12), which is connected upstream to the intake device (16) and is constructed as a Helmholtz resonator to reduce noise and stabilize combustion. To provide sufficient primary air under adverse spatial conditions the air supply chamber (11) has an exterior wall (11?) and a pattern (13, 14) of perforations in the exterior wall, which are formed as additional air inlets for additional supply of the primary air.

Abstract: The water heating apparatus has an upright cylindrical thermally insulated storage tank, an axially extending exhaust gas pipe passing centrally through the storage tank and a combustion chamber under the storage tank. An atmospheric gas burner, which has a complete premixing fuel gas/air supply system, is arranged within the combustion chamber. The exhaust gas pipe has a section extending within the combustion chamber, which preferably extends towards the bottom of the combustion chamber and has an end located a few centimeters from the bottom, so that the combustion gases have a longer dwell time in the combustion chamber and the exhaust gas pipe in order to improve heating efficiency.

Abstract: The gas-fired heater, especially a water heater, has an atmospheric gas burner (5) arranged within a nearly or completely closed combustion chamber (2) and associated with a premixing gas/air supply system (8) with a fuel gas feed nozzle (10). In order to avoid oscillations, which lead to sound waves and combustion instabilities, an oscillation-damping air supply chamber (11, 11?, 11?) is connected to the entrance (8a) of the gas/air supply system (8) for combustion air, within which the fuel gas feed nozzle is arranged. The air supply chamber (11, 11?, 11?) is provided with at least one air entrance (12, 12?, 12?). The air supply chamber can be box-like, duct-like embracing or extending around the combustion chamber or it can be a pipe with different diameter pipe sections.