Hot Water Flow Control for Dual Heat Generator Switching

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Solution Overview

Problem

Existing thermal engineering systems face inefficiencies in energy usage and comfort levels, particularly when switching between primary and secondary heat generators based solely on temperature sensors, which can lead to suboptimal energy consumption and reduced comfort during peak hot water demand.

Innovation Solution

Implementing a flow meter to detect hot water flow at the withdrawal point, switching the secondary heat generator on when the determined flow reaches a dynamically set withdrawal limit, allowing for more precise control between energy-efficient and comfort modes, especially using a heat pump and electric heating devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If temperature sensors are used to detect hot water extraction and switch between primary and secondary heat generators, then the system structure is simple, but energy efficiency is reduced and comfort is compromised during peak demand

Engineering Contradiction:
Improvesystem structureVSAvoidenergy efficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent replaces temperature-based detection (thermal sensing) with flow-based detection using a flow meter. This substitution enables precise measurement of hot water consumption rates, allowing the control system to accurately distinguish between low-demand and high-demand phases. The flow meter provides quantitative flow data that triggers appropriate heat generator selection, thereby improving energy efficiency without significantly increasing system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control mechanism where the flow meter continuously monitors hot water flow at the withdrawal point and feeds this information back to the control system. Based on the measured flow rate, the control system dynamically adjusts heat generator operation - using the energy-efficient primary heat generator during low flow conditions and switching to the secondary heat generator when flow exceeds the withdrawal limit. This closed-loop feedback ensures optimal energy efficiency while maintaining comfort.

Inventive Principle:
Principle #23Feedback

2Device complexity

If temperature sensors are used to control heat generator switching, then the control system is simple, but comfort during peak hot water demand is reduced

Engineering Contradiction:
Improvecontrol systemVSAvoiduser comfort
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent replaces temperature-based control with flow-based control using a flow meter positioned at the hot water withdrawal point. This substitution allows the system to directly measure the user's actual hot water consumption rate rather than inferring it from temperature changes. The flow meter's quantitative measurements enable the control system to respond more accurately to user demand, ensuring comfort is maintained during peak usage while keeping the control system relatively simple.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent establishes a feedback loop where flow measurements from the flow meter are continuously monitored and used to adjust heat generator operation in real-time. When the measured flow exceeds the predetermined withdrawal limit, the system switches to or activates the secondary heat generator to meet the increased demand. This feedback mechanism ensures that user comfort is prioritized during high-demand periods while maintaining energy efficiency during normal operation.

Inventive Principle:
Principle #23Feedback

3Loss of energy

If the primary heat generator is used exclusively during low demand phases, then energy efficiency is improved, but the system may not respond quickly enough to sudden increases in hot water demand

Engineering Contradiction:
Improveenergy efficiencyVSAvoidresponse speed to demand changes
Core Design Contradiction:
Loss of energyVSSpeed

Solution Approach 1:

The patent implements a dynamic control strategy where the system continuously adapts its operation based on real-time flow measurements. The control system monitors hot water flow rate and dynamically adjusts heat generator activation - maintaining energy-efficient operation with the primary heat generator during low-demand phases while being prepared to rapidly switch to or activate the secondary heat generator when flow exceeds the withdrawal limit. This dynamic response ensures both energy efficiency and rapid adaptation to changing demand conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs a preliminary action strategy by setting a predetermined withdrawal limit that anticipates potential demand increases. The flow meter continuously monitors flow against this threshold, and when the limit is approached or exceeded, the system proactively activates the secondary heat generator before a comfort deficiency occurs. This preliminary activation ensures the system responds quickly to sudden demand increases while maintaining energy efficiency during normal operation.

Inventive Principle:
Principle #10Preliminary action

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 approach enhances energy efficiency and user comfort by ensuring the primary heat generator is used during low demand and the secondary generator during high demand, optimizing energy usage and maintaining comfort even with small hot water storage tanks.

Implementation Method 1

the hot water flow occurring at a hot water withdrawal point is determined with a flow meter

Methodology Applied
Scientific EffectFlow measurement:

Implementation Method 2

the water is heated as energy-efficiently as possible with the primary heat generator, which is preferably designed as a heat pump device

Methodology Applied
Scientific EffectHeat pump thermal transfer: Heat Exchanger

Implementation Method 3

the secondary heat generator, which is preferably designed as an electric heating device

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4083520B1Method for operating a thermal engineering system
Publication Date: 2023.10.11 VIESSMANN CLIMATE SOLUTIONS SE
  • EP4083520B1 patent drawingFigure 1

AI summary

The invention relates to a method for operating a thermal system in which water is selectively heated by a primary heat generator (1) and/or by a secondary heat generator (2) that is less energy-efficient than the primary heat generator (1), stored in a hot water storage tank (3), and drawn from the hot water storage tank (3) for hot water supply. Up to a certain withdrawal limit, the water is heated exclusively by the more energy-efficient primary heat generator (1), and above this limit, it is heated at least by the secondary heat generator (2). According to the invention, when hot water is drawn from the hot water storage tank (3), a flow meter (4) determines the hot water flow rate at a hot water draw-off point (5), and the secondary heat generator (2) is switched on when the determined hot water flow rate reaches the withdrawal limit.