Multistage Gas Furnace High-Fire Ignition for Corrosion Control
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Solution Overview
Problem
Residential gas furnaces face challenges in passing the 100-day heat exchanger corrosion test, especially at low-fire rates, leading to increased costs and reduced efficiency due to the need for expensive materials or complex designs.
Innovation Solution
A controller for a multistage gas furnace that ignites at high-fire operation when the indoor circulating fan is active, transitioning to low-fire after a set period, thereby improving corrosion performance while minimizing noise dissatisfaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-fire ignition is used, then corrosion performance is improved, but noise levels increase
Solution Approach 1:
The system dynamically selects ignition mode (high-fire or low-fire) based on real-time detection of circulating fan status. When the fan is detected as active, high-fire ignition is used to improve corrosion performance; when the fan is inactive, low-fire ignition is used to minimize noise. This dynamic adaptation resolves the contradiction between corrosion performance and noise levels.
Solution Approach 2:
The ignition temperature parameter is changed based on fan operation status. High-fire ignition uses higher temperature parameters to achieve better corrosion resistance, while low-fire ignition uses lower temperature parameters to reduce noise. The controller adjusts this parameter dynamically according to fan status, resolving the contradiction.
2Object-generated harmful factors
If low-fire operation is used, then noise levels are reduced, but corrosion performance deteriorates
Solution Approach 1:
The system dynamically switches between low-fire and high-fire ignition modes based on circulating fan status. When the fan is inactive, low-fire ignition is used to minimize noise. When the fan becomes active, the system transitions to high-fire ignition to ensure adequate corrosion protection. This dynamic switching resolves the contradiction between noise reduction and corrosion performance.
3Reliability
If expensive stainless steel materials are used, then corrosion performance is improved, but manufacturing cost increases
Solution Approach 1:
Instead of changing material composition, the system changes operational parameters (ignition temperature and duration) based on fan status. By using high-fire ignition when the fan is active, the system achieves adequate corrosion performance with standard materials, avoiding the need for expensive stainless steel while maintaining reliability.
Solution Approach 2:
The circulating fan's operation serves a dual purpose: it provides necessary air circulation and simultaneously creates conditions (through its noise and air movement) that mask or tolerate the higher noise from high-fire ignition. This self-service approach allows the system to use high-fire ignition for corrosion protection without additional cost or separate masking systems.
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 corrosion resistance and reduces noise levels, making high-fire ignition beneficial for corrosion performance without increasing sound levels when the circulating fan is on, as the fan's operation masks the ignition noise.
Implementation Method 1
an inducer configured to draw combustion air through the heat exchanger
Implementation Method 2
a high fire pressure switch configured to close when flow of the combustion air has been established
Implementation Method 3
an indoor circulating fan configured to move air across the heat exchanger and into conditioned space
Data Source
AI summary
The disclosure provides a controller for a multistage gas furnace, a multistage gas furnace and computer readable medium for performing a method to operate a furnace. In one embodiment, the controller includes: (1) an interface configured to receive a heating call and (2) a corrosion reducer configured to ignite the gas furnace at a high fire operation based on if an indoor circulating fan of the gas furnace is active.