A forced-draft pre-mix burner device has a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet. A heat exchanger warms the air prior to discharge via the warm air outlet. A gas burner burns an air-gas mixture to thereby warm the heat exchanger. A fan mixes the air-gas mixture and forces the air-gas mixture into the gas burner. The fan has a plurality of blades having sinusoidal-modulated blade spacing.

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 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.

A combustion air blower, especially side channel blower, for a fuel-operated vehicle heater, includes a blower housing (38). An air flow space (44), through which combustion air being fed can flow, is formed in the blower housing (38). Air flowing over an inlet area (55) into the air flow space (44) flows to a feed area enclosing a feed wheel (48). At least one hydrocarbon storage element (70, 88) is formed in the air flow space (44), for storing gaseous hydrocarbon present in the air flow space (44).

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 heat exchanger arrangement (10), especially for a fuel-operated vehicle heater, includes an outer pot-shaped housing (12) having an outer bottom wall (16) and an outer circumferential wall (18) extending along a longitudinal axis (L). An inner pot shaped housing (14) has an inner bottom wall (20) and an inner circumferential wall (22) extending along the longitudinal axis (L). A flow space (24) for fluid whose temperature is to be regulated is formed between the inner housing (16) and the outer housing (12). At least one liquid uptake volume (46, 48) for taking up liquid condensed in the inner housing (14).

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 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.