Plastic Vent Structure for Instantaneous Water Heater Exhaust Cooling
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Solution Overview
Problem
Conventional fuel-fired instantaneous water heaters require expensive and difficult-to-install category III high-grade stainless steel vent systems due to high flue exhaust temperatures, making them costly and inconvenient to use.
Innovation Solution
A fuel-fired instantaneous water heater design that uses a low-cost plastic vent system by incorporating a blower to cool combustion gases to below 200°F, allowing them to be safely discharged through a plastic vent system instead of metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional power vented instantaneous fuel fired water heaters are installed indoors, then high flue exhaust temperatures are produced, but expensive and difficult-to-install stainless steel vent systems are required
Solution Approach 1:
The invention changes the temperature parameter of the exhaust gas by introducing cooling air into the vent system. The cooling air mixes with the hot combustion gases, reducing the temperature from several hundred degrees Fahrenheit to below 200°F, which enables the use of plastic vent materials instead of expensive stainless steel
Solution Approach 2:
Cooling air acts as an intermediary substance that is introduced into the vent system to absorb heat from the combustion gases. This intermediary cooling air allows the hot exhaust to be transformed into a cool enough flow to use cheaper plastic venting materials
2Temperature
If conventional power vented instantaneous fuel fired water heaters are installed indoors, then high flue exhaust temperatures are produced, but expensive stainless steel vent systems are required
Solution Approach 1:
The vent system is designed to perform multiple functions: it serves as both the exhaust pathway for combustion gases and as a cooling channel. By routing cooling air through the same vent structure, the system achieves both ventilation and temperature reduction without requiring separate cooling infrastructure
3Temperature
If conventional power vented instantaneous fuel fired water heaters are installed indoors, then high flue exhaust temperatures are produced, but costly vent systems are required
Solution Approach 1:
The invention replaces expensive, durable stainless steel vent components with cheaper plastic materials. While plastic may have shorter service life than stainless steel, the significant cost reduction makes it economically attractive for residential applications where the vent system can be replaced more easily
4Temperature
If cooling air is discharged into the third flow path to cool combustion gas, then the temperature of cooled combustion gas is reduced to enable plastic vent use, but additional air flow paths and cooling mechanisms are required
Solution Approach 1:
The cooling air flow path is merged with the existing vent structure rather than being a completely separate system. The third flow path is integrated into the housing and heat exchanger assembly, using available spaces and structures to route cooling air, thereby reducing overall system complexity
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
Enables the use of a low-cost plastic vent system while maintaining safety and efficiency, reducing installation complexity and material costs compared to stainless steel systems.
Implementation Method 1
discharge a second flow of air into the third flow path as cooling air which mixed with and cools combustion gas being discharged from the second flow path
Implementation Method 2
a second flow path extending therethrough, the second flow path being in thermal communication with the first flow path and adapted to receive a flow of hot combustion gas
Data Source
AI summary
An instantaneous type fuel-fired water heater has a variable speed blower that discharges combustion air into a fuel burner utilized to heat water flowing through a heat exchanger portion of the water heater. A portion of the air discharged from the blower bypasses the burner and associated heat exchanger, flows around the heat exchanger, and then mixes with flue gases being discharged from the heat exchanger portion into the flue portion of the water heater. In this manner, such flue gases are cooled by the bypassing blower discharge air to an extent permitting the flue portion to be formed from a low cost plastic material instead of a high temperature metal material such as stainless steel.