The invention discloses a control method and
system of a gas
water heater and the gas
water heater. The control method comprises the following steps that in the working process of the gas
water heater, the current opening degree of a gas
proportional valve of the water heater is monitored, and current practical
combustion heat quantity is worked out; whether the current opening degree of the gas
proportional valve and the current practical
combustion heat quantity accord with a preset
standard function relation is judged; when the current opening degree of the gas
proportional valve and the current practical
combustion heat quantity do not accord with the preset
standard function relation, it is determined that
gas pressure is insufficient, and a low
pressure control process is executed according to the current low pressure maximum
thermal load; when the current opening degree of the gas proportional valve and the current practical combustion heat quantity accord with the preset
standard function relation, a
normal control process is executed. By applying the method and
system to the gas water heater, the problems that because the
gas pressure is insufficient,
flameout and fire spreading are caused and the temperature of discharged water cannot reach a set temperature can be solved.