Safety power connecting system and method for electric water heaters
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Solution Overview
Problem
Electric water heaters face issues during power cuts, leading to water temperatures below 140 degrees F, which can allow the propagation of harmful bacteria like legionella, especially during load shedding periods or control device malfunctions, posing health risks and operational challenges.
Innovation Solution
A safety power switching system that continuously monitors the water temperature in the upper portion of the tank and communicates with the power provider to maintain power to the resistive heating elements if the temperature drops below 140 degrees F, ensuring the water remains at a safe temperature by automatically connecting or disconnecting power as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power is cut off during load shedding, then energy consumption is reduced, but water temperature drops below safe levels allowing bacteria propagation
Solution Approach 1:
The control device receives advance notice from the power provider about upcoming load shedding periods and pre-heats the water in the tank before power is cut off. This preliminary heating action ensures that water temperature remains above 140°F throughout the power interruption, preventing bacteria propagation while still allowing the power cut to occur for energy management purposes.
Solution Approach 2:
The system stores thermal energy in the form of heated water before the load shedding event occurs. By maintaining a reserve of hot water through prior heating, the system cushions against the temperature drop that would otherwise occur during power interruption, ensuring continuous safe water temperature without requiring power during the shedding period.
2Adaptability or versatility
If control devices are made more complex for remote monitoring and load control, then energy management capability is improved, but operation errors increase leading to improper temperature settings
Solution Approach 1:
The control device continuously monitors water temperature through temperature sensors and receives operational status from the power provider. This feedback mechanism allows the system to detect when water temperature approaches unsafe levels and automatically adjust heating operations or communicate with the power provider to prevent load shedding, thereby maintaining reliable temperature control despite the complexity of remote monitoring capabilities.
Solution Approach 2:
The control device autonomously manages temperature control by monitoring water temperature and automatically activating heating elements when needed, without requiring manual intervention. This self-service capability reduces the risk of user errors in setting temperatures or programming operations, while still providing the advanced energy management features of remote monitoring and load control.
3Stability of the object's composition
If power is progressively re-introduced after grid failure, then grid stability is maintained, but water temperature may drop during the re-introduction period
Solution Approach 1:
The control device maintains water temperature in the tank during the progressive re-introduction of power by pre-heating water before power is restored and continuing heating operations as power becomes available. This ensures that even during the extended re-introduction period when grid stability requires controlled power restoration, the water temperature remains above the 140°F safety threshold.
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
Prevents the propagation of harmful bacteria by maintaining water temperatures above 140 degrees F, ensuring user safety and reducing the risk of legionnaires' disease, while also addressing potential control device errors and power provider-initiated shutdowns during load shedding.
Implementation Method 1
A temperature sensor senses water temperature in an upper portion of a tank of the water heater
Implementation Method 2
power to the resistive heating elements of the water heater is shut off
Data Source
AI summary
A safety system and method to prevent water within a top portion of a tank of an electric water heater to drop below a safe temperature during a load shedding period, other than a full emergency grid failure, by a power provider whereby to prevent the propagation of harmful bacteria in a top portion the tank. A control device monitors the water temperature in the top portion of the tank by the use of a temperature sensor. If the control device detects a temperature of the water in the top portion of the tank inferior to 140 degrees F., it will by-pass the instructions of the power provider and connect power to one or more of the resistive heating elements of the tank until a predetermined temperature above 140 degrees F. is attained before switching off the resistive heating elements.