Electronic control system for electric water heater
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Solution Overview
Problem
Electric water heaters lack advanced control systems to prevent dry firing and optimize energy usage, leading to inefficiencies and increased operational costs.
Innovation Solution
A dual element electric water heater with a multifunction electronic control system that includes a dry fire protection algorithm and user-selectable performance and energy saver modes, utilizing non-simultaneous energization of heating elements and temperature sensing to manage heat demands and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simple electrical/mechanical heating control systems are used, then device complexity is reduced, but reliability and protection against dry firing deteriorate
Solution Approach 1:
The control system performs preliminary verification by activating the upper heating element before the lower heating element to ensure water presence and prevent dry firing conditions before they can occur
Solution Approach 2:
The system continuously monitors temperature differentials between upper and lower heating elements and uses this feedback to detect dry firing conditions, shutting down the system when abnormal temperature differentials indicate water level problems
2Adaptability or versatility
If sophisticated electronic control systems are implemented, then functionality and performance are enhanced, but device complexity increases
Solution Approach 1:
The electronic control system provides multiple operational modes including energy saver mode and performance mode, allowing a single device to adapt to different user needs and operating conditions
Solution Approach 2:
The control system dynamically adjusts heating element activation sequences and temperature setpoints based on selected operational modes, transitioning between different control strategies to optimize for either energy efficiency or performance
3Productivity
If continuous heating operation is used, then productivity is maintained, but energy consumption increases
Solution Approach 1:
The control system uses periodic temperature monitoring and differential-based control to activate heating elements only when and where needed, rather than continuous operation, maintaining hot water availability while reducing energy consumption
Solution Approach 2:
The system applies heating locally based on detected temperature differentials between upper and lower elements, activating only the necessary heating element(s) rather than continuous full-system heating
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
The system effectively prevents dry firing, optimizes energy usage by adjusting heating elements based on user-selected modes, and reduces operational energy costs by dynamically managing heat demands and setpoint temperatures.
Implementation Method 1
an upper heating element disposed within the tank and adapted to heat water in an upper portion of the tank and a lower heating element disposed within the tank and adapted to heat water in a lower portion of the tank
Implementation Method 2
an upper thermistor operative to sense a temperature of water in the upper portion of the tank and a lower thermistor operative to sense a temperature of water in the lower portion of the tank
Data Source
AI summary
In an electric water heater having adjustable set point and differential temperatures, upper and lower heating elements, and associated temperature sensors respectively operative to sense upper and lower tank water temperatures, a specially designed control system is provided for controlling the heating elements. The control system is operative to automatically set a selected setpoint temperature to a second setpoint temperature less than or equal to a predetermined magnitude, and to reduced the second setpoint temperature and/or the differential temperature, as a predetermined function of the magnitudes of detected time intervals between successive heat demands of the water heater, to reduce the energy cost associated with the water heater.