Dielectric Secondary Flue Assembly for Condensing Water Heaters
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Solution Overview
Problem
Existing condensing flue water heaters face challenges in increasing thermal efficiency due to complex and costly installation methods, which lead to premature deterioration of the sacrificial anode and reduced tank life, especially with large diameter second pass flues requiring welding and large holes in the tank wall.
Innovation Solution
A condensing flue water heater design featuring a secondary tubular flue mounted inside the tank with dielectric connectors that eliminate the need for welding, providing a self-sealing and leak-proof connection, thus preserving the tank's integrity and allowing for easier assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a large diameter second pass flue is installed to increase thermal efficiency, then heat exchange capability is improved, but the tank wall requires large holes and welding which causes metal exposure and accelerates sacrificial anode deterioration
Solution Approach 1:
A dielectric material is introduced as an intermediary between the metal flue and the tank wall, eliminating direct metal-to-water contact. The dielectric material fills the annular space between the flue and tank wall, providing electrical insulation that prevents galvanic corrosion while maintaining the heat exchange function of the flue.
Solution Approach 2:
The dielectric material serves as a sacrificial protective layer that can be easily replaced if needed, protecting the more critical tank structure and sacrificial anode from premature deterioration caused by metal exposure.
2Strength
If welding is used to secure the second pass flue to the tank wall, then connection strength is improved, but metal exposure increases leading to faster sacrificial anode consumption
Solution Approach 1:
The dielectric material acts as a mediator between the flue and tank wall, providing both mechanical support and electrical insulation. This eliminates the need for welding while maintaining connection integrity and preventing galvanic corrosion.
Solution Approach 2:
The mechanical welding process is replaced with a dielectric-based connection system that uses friction, compression, and adhesion to secure the flue, eliminating the harmful effects of welding-induced metal exposure.
3Use of energy by moving object
If the flue is extended to make a second pass into the tank for heat exchange, then thermal efficiency increases, but installation complexity and cost increase
Solution Approach 1:
The installation process is segmented into simple steps: cutting small holes, inserting the flue through dielectric material, and securing with compression fittings. This modular approach simplifies installation compared to traditional welding methods while maintaining thermal efficiency.
Solution Approach 2:
The dielectric material and compression fitting assembly provides a disposable, easy-to-install connection system that reduces installation complexity and cost while achieving the same thermal efficiency as welded installations.
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 design increases thermal efficiency up to 99% while simplifying installation, extending the life of the water heater by avoiding metal exposure and corrosion, and reducing assembly costs.
Implementation Method 1
a dielectric material positioned about an outer surface of the pressure flange to electrically isolate the pressure flange from the inner surface of the tank
Implementation Method 2
the flue is extended to make a second pass into the tank for heat exchange with the water being heated
Implementation Method 3
Such water heaters produce condensation and the heat released by the water vapor is relatively high and a large amount of energy of combustion is contained therein
Data Source
AI summary
A high efficiency condensing flue gas-fired water heater is provided with a secondary tubular flue mounted inside the water tank and secured thereto by dielectric connectors to electrically isolate the secondary tubular flue from the tank. The secondary tubular flue has an intermediate helical section and opposed connecting end sections which each form a part of the dielectric connectors. The connectors do not require any welding for its installation to the tank and a compression nut and dielectric insulators provide for a leak proof and electrically isolated connection. The method of securing the secondary tubular flue is also described.