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 combustion chamber assembly unit for a fuel-operated vehicle heater is provided. The combustion chamber assembly includes a combustion chamber housing (12) with a combustion chamber (18), which is defined by a circumferential wall (14) and by a bottom area (16). An oxidation catalytic converter device (54), through which combustion waste gases can flow, is provided downstream in relation to the combustion chamber (18). The combustion chamber assembly further includes a hydrocarbon storage device (74) or/and a nitrogen storage device (76).

A method to operate a fuel-operated vehicle heater comprising the lowering of a combustion air ratio λ between supplied combustion air and supplied fuel to a combustion chamber of the fuel-operated vehicle heater from a starting value λ.sub.start>1 to a range λ<λ.sub.start for a time period Δt.

A vehicle heater includes a burner assembly unit (12) with a combustion chamber (18) to be fed with combustion air (V) and fuel (B) and a flame tube (24). A heat exchanger assembly unit (14) includes an inner heat exchanger housing (28) with an inner circumferential wall (30) and an outer heat exchanger housing (34) with an outer circumferential wall (36). A heat transfer medium flow space (40) is between the inner and outer heat exchanger housings, which are elongated in a longitudinal axis (L) direction. A waste gas backflow space (44), between the inner circumferential wall (30) and the flame tube, opens towards an exhaust gas outlet. A catalytic converter device (52) is provided in the waste gas backflow space associated with an energizable heating unit (58), or/and insulation material (64) is provided on an outer side (62) facing away from the heat transfer medium flow space.

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 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 combustion chamber assembly unit for a fuel-operated vehicle heater includes a combustion chamber housing (14), a combustion chamber (18) formed in the combustion chamber housing (14), an evaporator medium (28) for the absorption of liquid fuel and for the discharge of fuel vapor into the combustion chamber (18), and a heating/ignition device (36) for heating the evaporator medium (28) or/and for igniting a mixture of fuel and combustion air formed in the combustion chamber (18). The heating/ignition device (38) includes at least one radiation source (38) for the emission of electromagnetic radiation into the combustion chamber (18) and at least one absorption body (29, 46) for the absorption of electromagnetic radiation emitted into the combustion chamber (18).

A vehicle heater includes a heat exchanger assembly unit (10) and a blower assembly unit (38). The heat exchanger assembly unit (10) has a first sealing surface (28) and the blower assembly unit (38) includes a second sealing surface (50), which is positioned opposite the first sealing surface (28) at a predefined location determined by the spacer arrangement (34). A sealing element (60) is clamped in between the first sealing surface (28) and the second sealing surface (50).

A combustion chamber assembly unit for a fuel-operated vehicle heater includes a combustion chamber housing (14) elongated in a direction of a housing longitudinal axis (L), with a combustion chamber (16) radially outwardly bounded by a circumferential wall (18), and with a combustion chamber bottom (20) axially delimiting the combustion chamber (16). A combustion air feed volume (36) is provided that is open to the combustion chamber (16) via a plurality of passage openings (38). A cooling medium feed device (46) is provided for feeding a liquid cooling medium to the combustion air feed volume (36).

A vehicle heater includes a burner area includes 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.