Gas water heater and wind pressure protection method and minimum load protection method thereof

The invention provides an air pressure protection method for a gas water heater, the gas water heater comprises a premixer, and the air pressure protection method comprises the following steps: (1) acquiring the gas secondary pressure SP and the air pressure FP of the premixer; (2) determining an alarm signal to be adopted according to the working condition, and determining the alarm signal and giving an alarm by adopting the following mode: when the wind pressure FP is lower than the lower limit value gmin (n) or higher than the upper limit value gmax (n), reporting a wind pressure fault; or when the gas secondary pressure SP is lower than the lower limit value fmin (n) or higher than the upper limit value fmax (n), a secondary pressure fault is reported. And when the external wind speed is increased, the rotating speed n of a fan of the gas water heater is increased, so that the gas secondary pressure SP and the wind pressure FP of the premixer reach the preset gas secondary pressure SP0 and the preset wind