Heating Furnace With Variable Fan Speed for Discharge Air Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heating systems face challenges in providing precise control over discharge air temperature, leading to issues like stratification and inefficient energy use, as they often operate in fixed modes without the ability to adjust speed or burner configuration effectively.
Innovation Solution
A heating system with a configurable air circulation fan and heating unit, utilizing a microprocessor to adjust fan speed and burner configurations based on temperature set points, allowing for multiple operating modes such as anti-stratification, energy saving, rapid response, and self-calibration, using a segmented gas manifold and variable speed fan for fine temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing heating systems operate at fixed heating stages (100% or 75% output), then the system can provide sufficient heat during peak periods, but the discharge air temperature becomes too high causing stratification and heating related issues
Solution Approach 1:
The system transitions from fixed heating stages to dynamic modulation by varying the air circulation fan speed continuously. The microprocessor controls the fan motor to operate at different speeds based on temperature feedback, allowing precise control of discharge air temperature and eliminating stratification issues caused by fixed high-temperature operation.
Solution Approach 2:
The invention changes the operating parameters of the heating system by introducing variable fan speeds instead of fixed heating stages. The system monitors discharge air temperature and adjusts fan speed accordingly, transforming the control mechanism from discrete stages to continuous parameter adjustment for optimal temperature control.
2Power
If the heating system is sized for peak heat periods, then maximum heat output is achieved, but the system cycles frequently and creates high discharge air temperatures
Solution Approach 1:
The system maintains maximum heat output capability when needed while avoiding frequent cycling by dynamically adjusting fan speed. During high heating demand, the fan operates at higher speeds to match the heating output, and during lower demand, it reduces speed proportionally, ensuring stable continuous operation and eliminating the on/off cycling problem.
Solution Approach 2:
The microprocessor continuously monitors discharge air temperature and uses this feedback to adjust fan speed in real-time. This closed-loop control prevents overheating and eliminates the need for frequent system cycling, improving operational stability while maintaining the ability to deliver maximum heat output when required.
3Productivity
If the air circulation fan operates at high speed to move more air, then heating coverage is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts fan speed based on actual heating requirements rather than operating continuously at high speed. The microprocessor monitors discharge air temperature and modulates fan speed to match the heating load, providing adequate heating coverage only when and where needed, thereby reducing unnecessary energy consumption.
Solution Approach 2:
The invention changes the fan operation from fixed high-speed mode to variable speed modes. By adjusting the fan speed parameter according to temperature feedback and heating demand, the system achieves optimal balance between heating coverage and energy consumption, operating at lower speeds when full heating capacity is not required.
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
The system achieves improved discharge air temperature control, reduces stratification, optimizes energy usage, and quickly adjusts to meet heating demands, enhancing overall system efficiency and comfort.
Implementation Method 1
a gas furnace, such as a residential gas furnace, is used in a heating system to heat the air
Implementation Method 2
a circulating fan is used to pull air from the enclosure into the HVAC system through ducts and to push the air back into the enclosure through additional ducts
Data Source
AI summary
A heating system comprising an air circulation fan, a heating unit, a memory that is operable to store a temperature map, and a microprocessor. The microprocessor is configured to operate the air circulation fan at a first speed and the heating unit in a first configuration. When the heating unit is in the first configuration, the heating unit is configured to achieve a first temperature and such that less than all of the burners are active. The microprocessor is also configured to receive a temperature set point and to determine a second speed for the air circulation fan using the temperature set point and the temperature map in response to receiving the temperature set point. Further, the microprocessor is configured to transition the air circulation fan from the first speed to the second speed in response to determining the second speed.