Instantaneous Water Heater Recirculation for Long Hot Water Draws
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Solution Overview
Problem
Existing water heating systems face challenges in maintaining a continuous supply of hot water while optimizing first hour ratings and reducing energy usage.
Innovation Solution
A water heating system comprising a water container, an instantaneous water heater, a pump, and a controller that operates the pump and burner to maintain a selected temperature, ensuring continuous hot water supply and preventing freezing, by sensing temperatures and adjusting the pump and burner operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the water heater operates continuously to maintain hot water supply, then the continuous hot water supply is improved, but the energy consumption increases
Solution Approach 1:
The controller continuously monitors water temperature in the container and adjusts pump and burner operation accordingly. When temperature drops below the set point, the pump activates to circulate water through the instantaneous heater; when temperature is sufficient, the pump stops, eliminating unnecessary energy consumption while maintaining reliable hot water supply.
Solution Approach 2:
The system dynamically adjusts its operation mode based on real-time temperature conditions. The pump operates intermittently rather than continuously, and the burner is ignited only when needed, creating a dynamic response that balances reliability with energy efficiency.
2Productivity
If the pump operates continuously to circulate water through the instantaneous heater, then the first hour rating is improved, but the energy consumption increases
Solution Approach 1:
The controller uses temperature feedback to determine when pump operation is necessary for improving first hour rating. The pump operates only when temperature drops below the set point, providing hot water circulation exactly when needed to maintain high productivity without continuous energy consumption.
Solution Approach 2:
The pump operates periodically rather than continuously, activating only when temperature conditions warrant it. This periodic operation maintains the first hour rating by ensuring hot water availability when needed, while significantly reducing overall energy consumption compared to continuous operation.
3Temperature
If the burner operates at high capacity to maintain temperature during continuous draws, then the temperature maintenance is improved, but the energy consumption increases
Solution Approach 1:
The burner operates dynamically based on real-time temperature conditions and draw rates. The controller monitors temperature continuously and ignites the burner only when temperature drops below the set point, adjusting operation to match actual heating needs rather than running at constant high capacity, thereby maintaining temperature while reducing energy consumption.
Solution Approach 2:
Temperature feedback controls burner operation. The controller compares actual temperature to the set point and activates the burner only when heating is required, ensuring temperature maintenance is improved while avoiding unnecessary energy consumption during periods when temperature is already sufficient.
4Object-affected harmful factors
If the pump operates to prevent freezing by circulating water, then the freeze protection is improved, but the energy consumption increases
Solution Approach 1:
The controller monitors temperature and activates the pump for freeze protection only when temperature drops below the freezing point or a predetermined threshold. This feedback-controlled operation provides improved freeze protection while minimizing energy consumption by operating the pump only when freezing conditions exist, rather than continuous operation.
Solution Approach 2:
The system takes preliminary anti-action against freezing by activating the pump when temperature approaches freezing conditions. This prevents freezing before it occurs while using energy only when necessary, rather than continuous operation that would consume excessive energy.
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 maintains a selected temperature above 100° F for an extended period, even during continuous water draws, while reducing energy consumption and preventing freezing, outperforming conventional systems in first hour ratings and recovery times.
Implementation Method 1
a heat exchanger located adjacent the burner between the tank supply inlet and the tank supply outlet
Implementation Method 2
a pump connected between the water container and the instantaneous water heater that moves water between the water container and the instantaneous water heater
Implementation Method 3
a burner, and a heat exchanger located adjacent the burner
Data Source
AI summary
A water heating system including a water container having a cold water inlet that connects to a water supply, a hot water outlet, a water heater outlet and a water heater inlet; an instantaneous water heater mounted to the water container and having a tank supply inlet connected to the water heater outlet, a tank supply outlet connected to the water heater inlet, a burner, and a heat exchanger located adjacent the burner between the tank supply inlet and the tank supply outlet; a pump connected between the water container and the instantaneous water heater that moves water between the water container and the instantaneous water heater; and a controller that operates the pump and the burner.