Tankless water heater with integrated variable speed pump
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Solution Overview
Problem
Traditional tankless water heaters face inefficiencies at lower temperatures and require complex temperature management due to narrow output temperature tolerances, leading to higher energy consumption and costly designs.
Innovation Solution
A tankless water heater system incorporating a variable speed pump and heat exchanger that dynamically adjusts flow rates and heat input to maintain a set point temperature within a ±10° F threshold, optimizing efficiency and reducing the turndown ratio from 13:1 to 5:1 (39,800-199,000 BTU/h), allowing for higher output temperature tolerance and simplified design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional tankless water heaters use large current flow or high Gas/BTU input to heat water, then water heating capability is improved, but energy consumption increases and system complexity increases
Solution Approach 1:
The patent applies a variable speed pump that dynamically adjusts its operation based on real-time temperature feedback from the heat exchanger outlet. This dynamic control allows the system to optimize water flow rate through the heat exchanger, ensuring efficient heat transfer while minimizing energy consumption. The pump speed varies to match the actual heating requirements rather than operating at fixed high capacity.
Solution Approach 2:
The system incorporates temperature sensors at the heat exchanger outlet that continuously monitor water temperature and provide feedback to the control system. This feedback mechanism enables the controller to adjust the variable speed pump operation in real-time, maintaining optimal heating efficiency while preventing energy waste from overheating or excessive flow rates.
2Measurement precision
If traditional tankless water heaters maintain narrow output temperature tolerances, then temperature control precision is improved, but device complexity and cost increase
Solution Approach 1:
The variable speed pump dynamically adjusts water flow rate through the heat exchanger based on temperature feedback, enabling the system to achieve precise temperature control through flow modulation rather than complex valve arrangements or multiple heating zones. This dynamic flow control simplifies the overall system architecture while maintaining temperature precision.
Solution Approach 2:
The system changes the flow rate parameter dynamically to achieve temperature control objectives. By varying the water flow rate through the heat exchanger rather than adjusting heat input or using complex temperature regulation mechanisms, the system achieves precise temperature control with simpler components.
3Ease of operation
If traditional tankless water heaters operate in cycles with fixed flow rate pumps, then recovery cycle operation is simplified, but heating efficiency and adaptability decrease
Solution Approach 1:
The variable speed pump replaces fixed flow rate pumps in recovery cycles, allowing the system to adapt flow rates to actual heating demands. During recovery cycles, the pump dynamically adjusts to optimize heat transfer efficiency while maintaining simple operational control through automated temperature-based feedback, achieving both efficiency and ease of operation.
Solution Approach 2:
Temperature feedback from the heat exchanger outlet continuously guides the variable speed pump operation during recovery cycles. This feedback mechanism automates the recovery process, maintaining simple operation while significantly improving heating efficiency through optimized flow rates that match actual thermal requirements.
4Adaptability or versatility
If traditional tankless water heaters use high turndown ratio (13:1), then adaptability to different temperature demands is reduced, but device complexity is increased
Solution Approach 1:
The system achieves a reduced turndown ratio of 5:1 by dynamically changing the water flow rate parameter through the variable speed pump. This parameter adjustment capability allows the heat exchanger to efficiently handle a wider range of temperature demands with a more compact, simpler system design compared to traditional 13:1 turndown ratios.
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 achieves increased efficiency and reduced costs by optimizing the turndown ratio and output temperature tolerance, enabling higher flu gas temperatures and using a category 1 vent, while maintaining precise temperature control and reducing energy waste.
Implementation Method 1
The variable speed pump has a heat exchanger, having an inlet and an outlet
Implementation Method 2
The variable speed pump has an inlet and an outlet. The variable speed pump has a heat exchanger
Data Source
AI summary
Various implementations include a water heater system. The system includes a variable speed pump. The variable speed pump has having an inlet and an outlet. The system includes a heat exchanger, having an inlet and an outlet. The heat exchanger outlet is fluidically connected to the variable speed pump inlet. The system includes an output temperature sensor disposed downstream of the heat exchanger outlet. The system includes a controller configured to receive a first temperature reading from the output temperature sensor. The controller is configured to control operation of the variable speed pump to adjust an output flow rate in response to the first temperature reading. The controller is further configured to receive a second temperature reading from a recovery temperature sensor on a storage tank. The controller is configured to turn off the variable speed pump upon a determination that the second temperature reading has reached a maximum temperature.