Modulating Furnace Blower Control for Efficiency and Comfort Balance
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Solution Overview
Problem
Modulating furnaces face a challenge in balancing energy efficiency and occupant comfort, as high circulating air blower speeds at higher firing rates can create a wind chill effect, reducing comfort while maintaining energy efficiency through constant discharge air temperature regulation.
Innovation Solution
Regulating the speed of the circulating air blower to allow a non-constant discharge air temperature that increases with higher burner firing rates, using sensors and models to determine or estimate discharge air temperature and flow, and allowing user preference settings to customize between energy efficiency and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the circulating air blower speed is increased to maintain constant discharge air temperature at higher firing rates, then energy efficiency is improved, but occupant comfort deteriorates due to wind chill effect
Solution Approach 1:
The patent changes the discharge air temperature parameter from constant to variable, allowing it to increase at higher firing rates. This enables the blower speed to be reduced at high firing rates while still meeting heating demands, thereby reducing the wind chill effect and improving occupant comfort while maintaining energy efficiency.
2Use of energy by moving object
If the circulating air blower speed is regulated to maintain constant discharge air temperature, then energy efficiency is maximized, but system flexibility deteriorates
Solution Approach 1:
The patent makes the discharge air temperature dynamic rather than static, allowing it to vary based on burner firing rate. This dynamic approach provides system flexibility to adapt to different operating conditions while maintaining energy efficiency, as the temperature can be adjusted according to actual heating needs at each firing rate level.
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 reduces the wind chill effect at higher firing rates while maintaining energy efficiency, allowing users to customize settings for improved comfort or efficiency based on their needs.
Implementation Method 1
a circulating air blower typically forces return air from the building, and in some cases ventilation air from outside of the building, over or through the heat exchanger, thereby heating the air
Implementation Method 2
a furnace employs a burner that burns a fuel such as natural gas, propane, oil or the like, and provides heated combustion gases to the interior of a heat exchanger
Data Source
AI summary
A furnace controller for a modulating furnace that helps provide a balance between energy efficiency and occupant comfort across various burner firing rates and/or across various circulating blower speeds. In some cases, the furnace controller can be configured to permit a user to customize operation of the furnace in accordance with their particular needs and/or desires with respect to efficiency and comfort. A selection may be made between an energy efficiency setting and a user comfort setting. Then, a plenum parameter such as a discharge air temperature (DAT) or discharge air flow (DAF) may be regulated in accordance with the selected setting.