Abstract: A device for mixing combustible gas and combustion air, hot water installation, and corresponding thermal mass flow sensor and method. The device includes an air line, a gas line with a control valve, a first measuring line connecting the air and gas lines, and a second measuring line connecting the first measuring line to the gas and/or air line, forming a three-way intersection. A thermal mass flow sensor includes first and second temperature sensors in the first measuring line, positioned respectively in a gas flow between the three-way intersection and the air line and in a gas flow between the three-way intersection and the gas line. A controller controls the control valve based on a difference, measured by the flow sensor, between mass flow rate of gas between the three-way intersection and the air line and mass flow rate of gas between the three-way intersection and the gas line.

Abstract: Fan housing for a fan for supplying a fuel/oxidizer mixture to a burner, comprising: a supply opening (22); a fluid supply space (26) debouching at the supply opening; a first supply means (28) for supplying a fluid-like fuel; a second supply means (52) for supplying an oxidizing fluid; wherein the fluid supply space comprises mixing means (50) for mixing the fluid-like fuel with the oxidizing fluid; and wherein the supply opening lies at an angle relative to the supply direction of the fluid in the fluid supply space.