Dual-Path Wall Thimble for Single-Penetration Combustion Venting
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Solution Overview
Problem
Existing fuel-burning appliance installations require separate openings in the wall for exhaust and combustion air, which is inefficient and increases the number of wall penetrations, whereas a single component that can handle both functions would simplify the installation and reduce the number of exterior wall openings.
Innovation Solution
A wall interface device, referred to as a 'wall thimble,' which integrates a vent path for exhausting combustion by-products and a separate air inlet path for drawing combustion air, allowing for a single opening in the exterior wall, utilizing dual-walled pipes and adjustable components for flexibility and compliance with building codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate openings are created in the wall for exhaust and combustion air, then proper venting and air supply functions are achieved, but the number of wall penetrations increases and installation complexity increases
Solution Approach 1:
The patent combines the exhaust venting function and combustion air supply function into a single integrated wall thimble component. The thimble includes an inner pipe for exhaust gases and an outer annular passage for combustion air, allowing both functions to be achieved through one wall penetration rather than requiring separate openings and components.
Solution Approach 2:
The wall thimble is designed as a multi-functional component that simultaneously serves as an exhaust outlet and an air inlet device. The single component performs multiple functions: venting combustion by-products through the inner pipe while drawing combustion air through the outer annular passage, eliminating the need for separate specialized components for each function.
Data Source
AI summary
An improved wall thimble as part of a venting apparatus for a heating appliance. Dual functionality is provided in a single wall thimble device by having a vent path for exhausting combustion by-products, and a separate air inlet path to draw in combustion air for use by the heating appliance. The wall thimble is preferably formed as a two-cylindrical part housing such that a first portion can be inserted into a second portion. When a smaller exhaust pipe is routed through the two-part housing, an annular region is formed between the exhaust pipe and the walls of the housing. A first air vent is formed in the first portion to draw combustion air into the annular region from outside. A second air vent is formed in the second portion to route the combustion air from the annular region out through the second air vent to be coupled with the combustion air inlet. A baffle is disposed in the first portion to preheat the combustion air. A duct assembly with an adjustable extension may be coupled to the second air vent to provide a below-grade installation.