Hot Water Storage Tank Control Using Temperature Drop Detection

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Solution Overview

Problem

Existing hot water devices with heat pumps face complexity and maintenance issues in regulating water temperature based on the amount drawn off, requiring multiple sensors and complex systems to ensure hygienic hot water supply as per guidelines like DVGW and DIN 1988.

Innovation Solution

A hot water device with a temperature sensor in the storage tank that detects rapid temperature drops to identify water tapping events, using a reference volume to determine setpoint temperatures, eliminating the need for flow sensors and allowing for simpler control unit reconfiguration or software upgrade to manage temperature settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If flow meters and mass/volume measurement devices are installed to accurately determine drawn water quantity, then temperature regulation accuracy is improved, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improvedrawn water quantity measurementVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the temperature regulation function from the flow measurement system. Instead of using flow meters to determine drawn quantity, the system uses a temperature sensor to detect temperature drops and a control unit to calculate drawn volume based on thermal energy balance, thereby eliminating complex flow measurement hardware while maintaining regulation accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces mechanical flow measurement devices with a thermal-based detection system. A temperature sensor monitors temperature changes in the storage tank, and the control unit uses these thermal measurements to infer drawn water quantity, substituting mechanical measurement with thermal field measurement

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

2Reliability

If multiple sensors and complex control systems are used to ensure hygienic hot water supply, then temperature regulation accuracy is improved, but ease of manufacture and maintenance are worsened

Engineering Contradiction:
Improvehygienic hot water supply assuranceVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The temperature sensor serves multiple functions: it monitors storage tank temperature for hygienic compliance, detects temperature drops to identify draw events, and provides data for calculating drawn volume. This multi-functionality eliminates the need for separate sensors while ensuring reliable hygienic hot water supply

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the existing thermal field and temperature variations in the storage tank as the measurement source, rather than requiring external active sensors. The temperature sensor passively detects natural temperature changes caused by water drawing, and the control unit self-calculates drawn volume from these measurements

Inventive Principle:
Principle #25Self-service

3Measurement precision

If flow sensors are installed to detect water usage patterns, then temperature control accuracy is improved, but device complexity and cost increase

Engineering Contradiction:
Improvewater usage pattern detectionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces thermal energy as an intermediary to indirectly measure water usage. Instead of directly measuring flow with sensors, the system measures temperature changes in the storage tank and uses thermal energy balance calculations to determine drawn water patterns, providing accurate detection without complex flow sensors

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution simplifies temperature regulation, reduces maintenance, and allows for cost-effective manufacturing by eliminating the need for flow sensors, while ensuring compliance with temperature guidelines through efficient detection of water usage patterns.

Implementation Method 1

The hot water storage tank (10) includes a measuring unit (11) for determining a temperature. It is particularly preferred that the measuring unit (11) is designed as a temperature sensor.

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 2

Heat transfer to the water can take place inside the hot water storage tank, for example by means of a tube heat exchanger, or outside the hot water storage tank, for example by means of a plate heat exchanger.

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP3671060B1Hot water device
Publication Date: 2023.06.07 STIEBEL ELTRON GMBH & CO KG
  • EP3671060B1 patent drawingFigure 1
  • EP3671060B1 patent drawingFigure 2

AI summary

The invention relates to a hot water device (1), in particular a heat pump, comprising a hot water storage tank (10) with a storage volume and a measuring unit (11), in particular a temperature sensor, for determining a temperature at a point within the hot water storage tank (10), wherein the hot water storage tank (10) has a water inlet (16) and a water outlet (18), wherein when a draw-off volume is taken from the water outlet (18) an inflow volume flows through the water inlet (16) into the hot water storage tank (10), a heat exchanger (20) for heating water in the hot water storage tank (10), and a control unit (30) which is configured to control the heat exchanger (20) such that the water in the hot water storage tank (10) has a first setpoint temperature (102) or a second setpoint temperature (103).