A fan includes: an impeller including a main plate having a first plane, a plurality of first blades each formed the first plane, and a shroud formed integrally with the plurality of first blades; a fan case; a drive source; and a rotation shaft. The first blades each include a linearly protruding region that is linearly increased in height from an outer circumferential side to an inner circumferential side, and a curvedly protruding region that is curvedly increased in height from the outer circumferential side to the inner circumferential side, the height extending in a direction in which each first blade protrudes. The linearly protruding region is welded to the main plate. Accordingly, a highly durable fan can be implemented that allows sufficient durability to be maintained even under a high temperature environment or an acid environment.

A portable water heater includes an inner bracket and a thermostatic chamber. A burner and a heat exchanger are arranged in the inner bracket. An upper end of the heat exchanger is provided with a fume collecting hood. The burner includes multiple fire rows arranged side by side, and the fire rows are connected to each other through a gas-distributing rod. The gas-distributing rod is provided with a segmented self-priming valve. A gas-regulating valve is provided on a gas inlet pipe. An inlet end of an internal heat-exchanging pipe of the heat exchanger is communicated with a cold water feeding pipe. The thermostatic chamber has a water inlet connected to a hot water delivering pipe and a water outlet connected to a hot water discharging pipe, and a connecting pipe is provided between the cold water feeding pipe and the hot water delivering pipe.

Provided is a gas water heater. The gas water heater includes a pre-mixer, a combustor having a combustion chamber in communication with a premixing chamber, a condensate water assembly configured to receive and discharge condensate water, and an apparatus for controlling the gas water heater. The pre-mixer includes a premixing chamber and an air intake fan that is configured to supply air to the combustion chamber. The air intake fan is disposed in the premixing chamber. The method includes: acquiring an intake air pressure threshold; acquiring an air intake pressure value of the air intake fan; and controlling, in response to determining based on the air intake pressure value and the intake air pressure threshold that a water seal of the condensate water assembly is at risk of being blown away, the gas water heater to stop operation.