Gas water heater and safety control method and system therefor

A gas water heater, comprising:

• a safety control system for a gas water heater, comprising:
• an exhaust fan, configured to exhaust waste gas generated when the gas water heater burns gas;
• a rotational speed detecting unit, configured to detect a rotational speed of the exhaust fan;
• a power obtaining unit, configured to obtain a set value for output power of the exhaust fan;
• a rotational speed difference obtaining unit, configured to obtain an actual value of the rotational speed and a reference value of the rotational speed according to the set value for the output power, and to calculate a difference between the actual value of the rotational speed and the reference value of the rotational speed;
• and
• an exhaust control unit, connected to the exhaust fan, the rotational speed detecting unit, the rotational speed difference obtaining unit and the power obtaining unit respectively, and configured to correct a predetermined wind pressure curve graph at an air outlet of the exhaust fan according to the difference, to determine a wind pressure situation at the air outlet according to the rotational speed, a corrected wind pressure curve graph and the set value for the output power, and to adjust the set value for the output power according to the wind pressure situation, wherein the predetermined wind pressure curve graph comprises a plurality of curves each indicating a predetermined rotational speed as a function of the set value for the output power.

A safety control method for a gas water heater, comprising:

• obtaining a set value for output power of an exhaust fan in the gas water heater and a reference value of a rotational speed of the exhaust fan corresponding to the set value for the output power;
• obtaining an actual value of the rotational speed according to the set value for the output power, and calculating a difference between the actual value of the rotational speed and the reference value of the rotational speed;
• correcting a predetermined wind pressure curve graph at an air outlet of the exhaust fan according to the difference, wherein the predetermined wind pressure curve graph comprises a plurality of curves each indicating a predetermined rotational speed as a function of the set value for the output power;
• detecting the rotational speed of the exhaust fan;
• and
• determining a wind pressure situation at an air outlet of the exhaust fan according to the rotational speed, a corrected wind pressure curve graph and the set value for the output power, and adjusting the set value for the output power according to the wind pressure situation.