Gas Water Heater Temperature Control for Anti-Stacking Demand Response
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Solution Overview
Problem
Conventional gas water heating devices face issues with temperature stratification ('stacking') and inefficient energy use due to large temperature differentials and unpredictable water demand, leading to either cold water complaints or excessive energy consumption.
Innovation Solution
A processor-controlled system that switches between anti-stacking and demand anticipation modes, adjusting the temperature differential and activation times based on sensor data to maintain a consistent water temperature, reducing stacking and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a large temperature differential setting (e.g., 20°F) is used to reduce stacking, then energy efficiency improves, but water temperature consistency deteriorates leading to cold water complaints
Solution Approach 1:
The patent implements dynamic adjustment of the temperature differential based on system state. The controller switches between a large differential (e.g., 20°F) during idle periods to save energy, and a small differential (e.g., 5°F) during active heating to maintain temperature consistency. This dynamic switching resolves the contradiction by adapting the differential setting to current operational conditions rather than using a fixed value.
Solution Approach 2:
The patent changes the temperature differential parameter based on detected conditions. When repeated short draws are detected indicating stacking conditions, the controller switches to a small differential. During normal idle operation, it uses a large differential for energy savings. This parameter change strategy allows the system to optimize both energy efficiency and temperature consistency at different times.
2Reliability
If a narrow temperature differential setting is used to maintain consistent water temperature, then water temperature consistency improves, but energy efficiency deteriorates due to frequent burner activation
Solution Approach 1:
The system dynamically adjusts the temperature differential parameter based on operational context. During idle periods with no hot water demand, it uses a large differential (e.g., 20°F) to minimize energy consumption. When demand patterns indicate potential stacking or during active heating cycles, it switches to a narrow differential (e.g., 5°F) to maintain temperature consistency. This dynamic adaptation resolves the energy-consistency tradeoff.
Solution Approach 2:
The controller anticipates stacking conditions by detecting repeated short draws and proactively adjusts the differential setting before significant temperature stratification occurs. This preliminary action prevents the need for continuous narrow differential operation, thereby maintaining temperature consistency only when necessary while preserving energy efficiency during normal operation.
3Loss of energy
If the burner is activated only after the setpoint temperature is reached, then energy efficiency improves, but water delivery temperature deteriorates for unexpected large draws
Solution Approach 1:
The system performs preliminary detection of demand patterns by monitoring repeated short draws. When such patterns are detected, the controller proactively switches to a narrow temperature differential setting before a large draw occurs. This preliminary action prepares the system to respond more quickly to unexpected large demands, ensuring temperature consistency without requiring premature burner activation during normal operation.
Solution Approach 2:
The controller continuously monitors hot water draw patterns and uses this feedback to adjust the temperature differential setting. When feedback indicates repeated short draws (stacking conditions), the system adjusts the differential to maintain temperature consistency. This feedback mechanism allows the system to balance energy efficiency and delivery temperature reliability based on actual usage patterns rather than fixed settings.
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 mitigates temperature stratification and ensures a consistent water temperature, enhancing user satisfaction and reducing energy consumption by optimizing heating cycles based on actual demand.
Implementation Method 1
receive an output from a sensor indicating a measured temperature of water in the water heater
Implementation Method 2
a burner configured to heat the water in the water heater
Implementation Method 3
control the burner to heat the water in the water heater based on the reduced activation time
Data Source
AI summary
A processor for a controller of a water heater is configured to receive water heater control parameters and an output from a sensor indicating a measured temperature of water in the water heater. The processor is also configured to determine whether to enter an anti-stacking control mode or to enter a demand anticipation control mode. In the anti-stacking control mode the processor is configured to initiate a call for heat when the measured temperature reaches a trigger temperature, calculate a burner on delay value and set a second timer with the calculated value, and calculate a reduced activation time. In the demand anticipation control mode the processor is configured to increase the variable offset based on a frequency of the demand anticipation control mode being activated, initiate a call for heat, and control, based on the reduced activation time or the increased offset value, the burner.