Hot-Water Tank Reheating Control for Bacterial Suppression
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Solution Overview
Problem
Hot-water supply systems with instantaneous heating types connected downstream of a hot-water tank face challenges in preventing bacterial growth when the temperature setting for boiling is not regularly maintained, leading to potential bacterial contamination in the water supply.
Innovation Solution
A hot-water supply system that includes a hot-water tank, sensors for temperature and flow detection, and regulation valves to control the mixing of water from the tank and an external supply, ensuring the water is heated to a sterilization temperature when necessary, and maintaining the flow to prevent bacterial reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hot-water in the hot-water tank is periodically boiled to high temperature to sterilize bacteria, then the bacterial contamination is reduced, but the energy consumption increases and the system complexity increases
Solution Approach 1:
The system uses the instantaneous heating apparatus and mixing valves to self-regulate water temperature on-demand, eliminating the need for periodic high-temperature boiling cycles. The control unit automatically mixes hot and cold water to maintain safe temperatures without manual intervention or energy-intensive sterilization cycles.
Solution Approach 2:
The system changes the temperature parameter dynamically by mixing hot water from the tank with cold water from the supply pipe. Instead of maintaining constantly high temperature for sterilization, the system adjusts temperature parameters to achieve safe water supply at lower energy consumption.
2Reliability
If the hot-water in the hot-water tank is periodically boiled to high temperature to sterilize bacteria, then the bacterial contamination is reduced, but the device complexity increases
Solution Approach 1:
The control unit automatically monitors tank temperature and operates the instantaneous heating apparatus and mixing valves to maintain safe water temperatures. This self-regulating system replaces complex periodic sterilization cycles with simple on-demand temperature control.
Solution Approach 2:
The cold water from the supply pipe acts as an intermediary to mix with hot water from the tank, enabling temperature regulation without requiring the hot water to reach sterilization temperatures. This intermediary approach simplifies the system compared to direct high-temperature sterilization.
3Use of energy by moving object
If the instantaneous heating apparatus heats water on-demand through mixing control, then the energy consumption is reduced, but the temperature regulation complexity increases
Solution Approach 1:
The control unit automatically performs temperature regulation by monitoring tank temperature and adjusting the mixing ratio of hot and cold water. This self-service temperature control eliminates manual intervention and simplifies operation despite the automated control logic.
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 system effectively prevents the supply of hot-water with high bacterial content by ensuring the water is heated to sterilization temperatures when required, reducing energy consumption and maintaining a safe water supply even without regular boiling settings.
Implementation Method 1
a heating unit configured to heat water in the hot-water tank
Implementation Method 2
a hot-water supply apparatus disposed in the midway of the hot-water supply pipe at a downstream side of the joint location between the hot-water supply pipe and the water supply pipe for heating the water flowing through the hot-water supply pipe
Implementation Method 3
to perform a temperature regulation control via mixing by prohibiting the heating by the hot-water supply apparatus and regulating a mixing ratio of the hot-water supplied from the hot-water tank to the hot-water supply pipe and the water supplied from the water supply pipe to the hot-water supply pipe
Data Source
AI summary
When a detection temperature by a hot-water tank thermister (42) has been equal to or lower than a re-heating determination temperature over at least a re-heating determination time, a tank controller (50) performs a sterilization process by heating hot water within a hot-water tank (30) by means of a heat pump unit (60); and when the detection temperature by the hot-water tank thermister (42) has been equal to or lower than a determination temperature for prohibiting the use of hot water in the hot-water tank over at least a determination time for prohibiting the use of hot water in the hot-water tank, the tank controller (50) performs only a temperature regulation control via heating while keeping a hot-water flow regulation valve (34) in a closed state.