Water heater and method for controlling a water heater
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Solution Overview
Problem
Modern tankless water heaters with bare wire heating elements face issues of excessive leakage currents and overheating due to air bubbles, which existing control methods fail to adequately address, leading to potential damage and user safety risks.
Innovation Solution
A water heater system with a measuring sensor having two electrodes in the flow channel, applying an alternating voltage to measure resistance and control the heating element's output based on predefined threshold values, allowing for direct comparison and interruption of heating when resistance falls below a critical level, thereby preventing excessive leakage and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a bare wire heating element is used to heat water, then heating efficiency is improved, but leakage currents increase and overheating risk occurs
Solution Approach 1:
The patent applies preliminary action by measuring the electrical resistance of water before the heating element operates. The control unit evaluates the measured resistance value against threshold values to determine whether to activate the heating element. This preventive measurement approach identifies unsuitable water conditions (high conductivity, air bubbles, contamination) before heating begins, preventing leakage currents and overheating while maintaining efficient heating operation when conditions are appropriate.
Solution Approach 2:
The patent introduces an intermediary measurement system consisting of a measuring sensor with two electrodes and a control unit. This intermediary evaluates the electrical resistance of water as an intermediate parameter to infer water quality and suitability for heating. By using this intermediary assessment, the system indirectly detects conditions that would cause harmful leakage currents or overheating without directly measuring those harmful effects, enabling safe operation of the bare wire heating element.
2Object-affected harmful factors
If conductivity measurement is used to control leakage current, then leakage current control is achieved, but the controlled variable deviates from the measured variable and damage prevention is insufficient
Solution Approach 1:
The patent changes the measurement parameter from electrical conductivity to electrical resistance. By measuring resistance (which is inversely related to conductivity) and comparing it against threshold values, the system obtains a more direct and reliable indicator of water suitability for heating. This parameter change provides better correlation with actual heating safety conditions, enabling more reliable prevention of damage from leakage currents and overheating while maintaining effective leakage current control.
3Temperature
If an optical sensor is used to detect wire glow, then overheating detection is achieved, but device complexity and costs increase
Solution Approach 1:
The patent replaces the optical sensor system (which would require complex structural modifications and multiple sensors to monitor the heating element surface) with an electrical resistance measurement system. By measuring the electrical resistance of water before heating, the system indirectly detects conditions that would lead to overheating (such as air bubbles or contamination) without requiring direct optical monitoring of the heating element. This substitution significantly reduces device complexity while maintaining effective overheating prevention.
Solution Approach 2:
The patent uses water electrical resistance as an intermediary parameter to predict overheating risk before it occurs. Instead of directly monitoring the heating element temperature or glow with complex optical sensors, the system measures the resistance of water as an intermediate indicator that correlates with heating safety. This intermediary approach provides early warning of potential overheating conditions with simple electrical measurements, avoiding the need for complex thermal or optical monitoring systems.
4Measurement precision
If multiple optical sensors are used to monitor the entire heating element area, then overheating detection accuracy is improved, but device complexity increases significantly
Solution Approach 1:
The patent extracts the essential safety function from complex optical monitoring by identifying that water electrical resistance measurement contains sufficient information to predict overheating risk. Instead of extracting multiple optical sensors to cover the entire heating element surface, the system uses a single electrical resistance measurement of the water as a proxy indicator. This extraction approach achieves adequate overheating detection accuracy with minimal complexity by focusing on the root cause (water conditions) rather than the symptom (heating element glow).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures safe operation by reliably detecting resistance changes, preventing excessive leakage currents and overheating, and providing user safety by interrupting heating power when critical conditions are met, without the need for complex calculations or additional sensors.
Implementation Method 1
a measuring sensor (21) which has two spaced-apart electrodes extending into the flow channel and is designed to detect a resistance of a fluid flowing through the flow channel by applying an alternating voltage between the two spaced-apart electrodes
Implementation Method 2
one or more electrical heating elements, which, depending on the electrical power supplied to the heating elements, can heat a fluid, typically water, flowing through channels in the instantaneous water heater
Data Source
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AI summary
The invention relates to an electric through-flow heater (100), in particular an electronic through-flow heater, a hot water system, a drinking water heat pump, a small reservoir, a wall reservoir, a standing reservoir, and/or a boiling water heater for providing hot water, and to a corresponding method. The through-flow heater comprises a flow channel (9, 10, 11), which comprises a heating section (10); a heating element (12), in particular a bare-wire heating element which is arranged in the region of the heating section; a measuring sensor (21) which has two electrodes (22, 22') that are mutually spaced and reach into the flow channel and which is designed to measure the resistance of a fluid flowing through the flow channel (9, 10, 11) by applying an AC voltage between the two mutually spaced electrodes (22, 22'); and an electronic controller (3) for controlling the electric through-flow heater, wherein the electronic controller (3) is designed to control the heat output of the heating element (12) on the basis of the measured resistance, in particular to interrupt the heat output if a resistance threshold is undershot and/or exceeded.