A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

A fuel connection unit (10) for a fuel-operated vehicle heater (18) includes a connection unit body (12), which can be arranged at a heater housing (16). A fuel release line connection area (32) connects a fuel release line leading to a combustion chamber. A fuel feed line connection area (46) projects from the connection unit body (12) for connecting a fuel feed line. At least one functional unit (50), for influencing the flow of fuel in a fuel flow volume (36) formed in the connection unit body (12), is provided in the connection unit body (12).

A burner device (190) comprising an air intake, a burner head (192) including an ignition device, a body section (196) defining a fluid flow channel between said air intake and said burner head (192), and a gas injector (205) for injecting combustible gas into said fluid flow channel. The burner head (192) is oriented such that its longitudinal axis is substantially perpendicular to the plane in which the channel is defined and in which fluid flows, in use, along said channel.

A fuel gas-operated vehicle heater includes a burner area with a combustion chamber (60) formed in a combustion chamber housing (58). The combustion chamber housing (58) includes a circumferential wall (62) defining the combustion chamber (60) in relation to a housing longitudinal axis radially outwards and a bottom area (64) axially defining the combustion chamber (60). The bottom area (64) has a fuel gas feed chamber (116) between a first bottom wall (106) defining the combustion chamber (60) and a second bottom wall (112). A fuel gas feed line (118) opens into the fuel gas feed chamber (116). A fuel gas inlet opening assembly is provided in the first bottom wall (106) for the entry of fuel gas from the fuel gas feed chamber (116) into the combustion chamber (60).

A fuel connection unit for a fuel-operated vehicle heater includes a connection unit body (12) to be mounted on a heater body (78). A fuel release line connection area (16) is positioned such that it meshes with or faces an interior (80) of the heater body (78). The fuel release line connection area (16) connects a fuel release line (104), extending in the interior (80), with a fuel feed line connection area (20) to be positioned exposed on an outer side of the heater body (78), for connecting a fuel feed line.

A heater comprises a combustion chamber and a jacket extending about the combustion chamber. There is a fan having an output which communicates with the combustion chamber to provide combustion air. There is also a fuel delivery system having a variable delivery rate. A burner assembly is connected to the combustion chamber. The burner assembly has a burner mounted thereon adjacent the combustion chamber. The burner receives fuel from the fuel delivery system. There is an exhaust system extending from the combustion chamber. An oxygen sensor is positioned in the exhaust system to detect oxygen content of exhaust gases. There is a control system operatively coupled to the oxygen sensor and the fuel delivery system. The control system controls the delivery rate of the fuel delivery system according to the oxygen content of the exhaust gases.

A vehicle heater includes a burner area, a circumferential wall providing a combustion chamber, a flame tube with a first end forming or adjacent to a part of the combustion chamber circumferential wall and a second flame tube end. A heat exchanger housing has a circumferential wall enclosing the flame tube. A waste gas backflow space is formed, between an outer side of the flame tube and an inner side of the heat exchanger housing circumferential wall, with an inlet area at the second flame tube end and with an outlet area in the area of the first flame tube end. An inner dimension of the circumferential wall increases in the direction from an inlet area of the waste gas backflow space to an outlet area. An outer dimension of the flame tube increases in the direction from the second flame tube end to the first flame tube end.

A process for manufacturing a cast metal heat exchanger housing (12) for a vehicle heater having a pot-shape housing wall (14) extending in a direction of a housing longitudinal axis (L) and having a plurality of heat transfer ribs (22) extending on an outer side of the housing wall (14) in the area of a circumferential wall (16) and in the area of a bottom wall (18) of the housing wall (14) in the direction of the housing longitudinal axis (L). The process includes metal casting wherein a sprue cross-sectional area including at least some of the heat transfer ribs (22). The cast metal heat exchanger housing has an axial end face formed upon cutting off metallic material that is essentially at right angles to the housing longitudinal axis and extends into an area of at least some of the heat transfer ribs.

A method for operating a fuel-operated vehicle heater, wherein after receipt of a switch-off signal by a control unit of the fuel-operated vehicle heater, a shutdown phase is initiated, during which remaining fuel present in the fuel-operated vehicle heater is combusted, and wherein a restart phase is initiated by the control unit after receipt of a switch-on signal during the shutdown phase, without the shutdown phase being terminated after complete combustion of the remaining fuel.

A fuel-operated vehicle heater includes a burner area (12) with a combustion chamber (14); a fuel pump (24); and a combustion air blower (28). A pressure sensor (38) detects a feed back pressure. An actuating unit (36) actuates the fuel pump (24) with a predefined value of a pump operating variable, and actuates the combustion air blower with a predefined value of a blower operating variable. A heater process includes detecting the feed back pressure in case of a feed operating state set during the combustion operation and comparing the detected feed back pressure (P.sub.e) with an expected feed back pressure (P.sub.E) for the set feed operating state. If the detected feed back pressure deviates from the expected feed back pressure the pump operating variable is changed such that the feed back pressure changes toward the expected feed pressure and/or essentially corresponds to the expected feed back pressure.