Multiple hot water supply system
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Solution Overview
Problem
In multiple hot water supply systems, solenoid valves in the fuel gas supply part of hot water supply devices can become fixed in the closed state during prolonged standby, leading to issues with combustion initiation, especially in systems where auxiliary devices are infrequently activated, resulting in reduced chances of activation and potential failure.
Innovation Solution
A control device calculates the continuous standby time of each hot water supply device and prioritizes the device with the longest standby time to supply hot water during the next operation, ensuring the solenoid valves are driven before potential fixation, and also equalizes cumulative hot water supply operation times to prevent wear and deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary hot water supply devices standby for long periods, then system reliability is improved by having devices ready to activate, but solenoid valves become fixed in closed state and combustion cannot be initiated
Solution Approach 1:
The control device implements periodic activation of standby hot water supply devices by selecting one device based on accumulated standby time and forcing it to operate temporarily. This periodic action prevents solenoid valves from remaining closed too long, maintaining their operational reliability without requiring continuous operation of all devices.
Solution Approach 2:
The control device calculates accumulated standby time for each device in advance and proactively selects a device for temporary operation before its solenoid valves become fixed. This preliminary action prevents the fixation problem from occurring by ensuring devices are activated before reaching critical standby durations.
2Productivity
If main hot water supply device operates continuously, then hot water supply capacity is ensured, but operational wear is concentrated on one device reducing overall system longevity
Solution Approach 1:
The control device dynamically adjusts the main hot water supply device selection based on accumulated operation times of all devices. By continuously monitoring and recalculating which device has the lowest accumulated operation time, the system dynamically redistributes operational load, extending the overall system lifespan while maintaining continuous hot water supply capacity.
3Device complexity
If auxiliary devices are activated later in sequence, then system complexity is reduced with clear activation hierarchy, but later devices have fewer chances to activate increasing fixation risk
Solution Approach 1:
The control device uses feedback from accumulated standby time measurements to adjust activation decisions. By continuously monitoring how long each device has been in standby and using this information to select which device should operate temporarily, the system maintains simple hierarchical control while ensuring reliability through data-driven decisions about which device needs activation.
Data Source
AI summary
In a multiple hot water supply system (10) including: multiple hot water supply device (11 to 14); and a control device (15) increasing/decreasing an operating device number of a hot water supply operation performed by the hot water supply devices (11 to 14) according to a demanded hot water supply capacity, the control device (15) includes a function of calculating a continuous standby time of each hot water supply device (11 to 14), and, when there is a hot water supply device whose continuous standby time exceeds a reference standby time set in advance, exerts control so that the hot water supply device most preferentially supplies hot water during a next hot water supply operation.