US 8,126,320 B2 · Methods for preventing a dry fire condition and a water heater incorporating same

Abstract

Methods of determining the likelihood of the existence of a dry fire condition in a hot water heater without requiring energization of any of the heating elements are presented. Such methods utilize only the sensor inputs required for normal operation of the hot water heater. Such sensory inputs are characterized in a process of fuzzification to enable the utilization of fuzzy logic rules to determine the likelihood of a dry fire condition before any energization of a heating element occurs. Alternatively, the sensory inputs are assigned logical values and are processed using Boolean logic to determine if a dry fire condition exists, prior to the energization of any electrical heating element within the hot water heater. Upon the determination that a dry fire condition is likely, the controller may perform a soft or hard lockout, may allow reset(s), and may provide an indication to the user of the condition.

Claims10

Dependent claims

A method of preventing a dry fire condition in a liquid heating appliance having a tank in which liquid is heated by at least one electrical heating element, the appliance including at least one sensor required for normal operation thereof, comprising the steps of:

without energizing the at least one electrical heating element, reading the at least one sensor and determining whether a dry fire condition would occur if the heating element were energized based on the reading of the at least one sensor;
and
when the step of determining indicates that a dry fire condition is not likely, allowing energization of the at least one electrical heating element under normal control;
and
when the step of determining indicates that a dry fire condition is likely, disabling energization of the at least one electrical heating element for at least a period of time;
wherein the step of determining comprises the steps of:
calculating a temperature parameter from the reading of the at least one sensor;
characterizing the temperature parameter into a fuzzy value;
applying at least one fuzzy logic rule to the fuzzy value;
and
performing defuzzification of a result of the step of applying to determine if a dry fire condition is likely or not if energization of the at least one electrical heating element is permitted.

8 more elements

without energizing the at least one electrical heating element, reading the at least one sensor and determining whether a dry fire condition would occur if the heating element were energized based on the reading of the at least one sensor;
and
when the step of determining indicates that a dry fire condition is not likely, allowing energization of the at least one electrical heating element under normal control;
and
when the step of determining indicates that a dry fire condition is likely, disabling energization of the at least one electrical heating element for at least a period of time;
wherein the step of determining comprises the steps of:
calculating a temperature parameter from the reading of the at least one sensor;
assigning logical values to the temperature parameter;
and
applying at least one Boolean logic rule to the logical value to determine if a dry fire condition is likely or not if energization of the at least one electrical heating element is permitted.

7 more elements

Dependencies are inferred from the claim text.

Methods for preventing a dry fire condition and a water heater incorporating same

Life of this patent

Methods for preventing a dry fire condition and a water heater incorporating same

Life of this patent

Abstract

Claims10