Method for sanitizing water supply system
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Solution Overview
Problem
Existing heating systems with large thermal storage tanks face challenges in preventing Legionella proliferation due to stagnant water at temperatures conducive to bacterial growth, especially when hot water demands are sporadic, making frequent testing economically unfeasible and ineffective.
Innovation Solution
A compact under-sink heating system with an ozonation control method that uses a controller, flow meter, and ozonator to determine low flowrate periods and apply ozone sanitization strategically, ensuring water is sanitized at the point of use without requiring continuous ozonation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a large thermal storage tank is used to meet hot water demands, then the heating system can supply hot water for extended periods, but stagnant water at temperatures suitable for Legionella proliferation occurs when hot water demands are small
Solution Approach 1:
The system performs ozonation in advance during periods of no water demand to sanitize the water before Legionella can proliferate. The controller monitors flowrate and activates the ozonator proactively when stagnation is detected, preventing bacterial growth before it occurs rather than reacting after contamination happens.
Solution Approach 2:
The system changes the chemical parameter of the water by introducing ozone, which oxidizes and kills Legionella bacteria. This chemical transformation converts safe water into sanitized water, and the effect persists through the stored hot water, maintaining safety even during extended storage periods.
2Measurement precision
If frequent water testing is conducted to detect Legionella, then the presence of Legionella can be ascertained, but the frequency and costs of testing balloon quickly making it economically unfeasible
Solution Approach 1:
The system replaces the mechanical/testing-based Legionella detection method with a chemical ozonation method. Instead of periodically sampling and lab-testing water for Legionella presence, the system continuously sanitizes the water using ozone injection, providing ongoing protection without the need for expensive frequent testing.
Solution Approach 2:
The water supply system sanitizes itself through automated ozonation controlled by a controller that monitors flowrate conditions. The system serves its own sanitation needs without requiring external testing services, making the process economically self-sufficient.
3Reliability
If ozone injection is applied at a central location in a distributed water supply network, then water can be sanitized, but the ozonated water flow can be re-contaminated as it flows through points of use
Solution Approach 1:
The system divides the water supply into segments and applies ozonation at multiple locations including points of use. By segmenting the sanitation approach, each section of the distributed network receives localized ozonation treatment, preventing re-contamination in individual fixtures while maintaining overall system hygiene.
4Object-affected harmful factors
If continuous ozonation is applied to sanitize water, then Legionella risk is reduced, but energy consumption and operational costs increase
Solution Approach 1:
The system applies ozonation periodically rather than continuously, activating the ozonator only during periods of no water demand when stagnation is detected. This pulsed ozonation approach maintains sanitation effectiveness while dramatically reducing energy consumption compared to continuous operation.
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 reduces Legionella risk by sanitizing water at the point of use, recovering heat energy from drain water, and minimizing scaling, while being self-sustaining and energy-efficient, without the need for frequent testing or tank-based stratification.
Implementation Method 1
A compact under-sink heating system with an ozonation control method that uses a controller, flow meter, and ozonator to determine low flowrate periods and apply ozone sanitization strategically
Implementation Method 2
Left at a temperature of about 66 degrees C. (150.8 degrees F.), legionellosis die within 2 minutes. At 70 degrees C. (158 degrees F.) or above, legionellosis is killed
Implementation Method 3
The heat pump system has a refrigerant path, at least a portion of which is in thermal communication with the water tank volume such that heat transfers from a refrigerant to the water tank volume
Implementation Method 4
a flow meter configured for detecting a flowrate through the water supply system
Data Source
AI summary
A method for controlling ozonation in a water supply system including an ozonator, a controller functionally connected to the ozonator, a flow meter configured for detecting a flowrate through the water supply system, a valve configured for turning on or off of the water supply system, the method including using the controller for; determining at least one event from flowrate data of the flow meter over a time period of a plurality of days, the at least one event including a time span of a day in which the flowrate remains below or at a threshold value over the time span of a day within each day of the plurality of days; determining overlaps of the at least one event of all days within the time period; determining a frequency of the overlaps of the at least one event over the time period and determining a requirement for ozone.