Smart thermostat fan controller
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Solution Overview
Problem
Existing HVAC fan controllers waste energy by providing unnecessary fan-off delays, increasing energy consumption, especially when buildings are unoccupied, and fail to efficiently manage fan operation based on thermostat signals.
Innovation Solution
A smart thermostat fan controller that monitors fan G, AC Y, and heat W signals to prevent fan-off delays when these signals are not activated, optimizing fan operation and reducing energy waste by only energizing the fan when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a fan-off delay is provided after every fan G signal from the thermostat, then the fan operates longer than the user selected hourly or intermittent fan-on duration, but this increases fan energy use by 20 to 50%
Solution Approach 1:
The patent extracts the harmful fan-off delay function from the fan controller when the building is unoccupied. The controller detects unoccupied status and removes the delayed turn-off feature, allowing the fan to turn off immediately when the thermostat stops signaling, thereby eliminating unnecessary energy consumption during unoccupied periods.
Solution Approach 2:
The patent makes the fan controller's behavior dynamic by adjusting its operation based on occupied/unoccupied status detection. The controller adapts between two modes: providing fan-off delays when occupied (for comfort) and eliminating delays when unoccupied (for energy savings), optimizing performance based on real-time conditions.
2Loss of energy
If the fan operates during hourly or intermittent fan-on periods when the building is unoccupied, then HVAC energy is wasted, but preventing fan operation may reduce occupant comfort upon return
Solution Approach 1:
The patent performs preliminary detection of unoccupied status before the fan-on period begins. By detecting unoccupied conditions in advance, the system can prevent unnecessary fan operation during scheduled fan-on periods, avoiding energy waste before it occurs. The system maintains comfort reliability by ensuring the fan operates when occupancy is detected.
3Device complexity
If known fan controllers provide fan-off delays using the fan G signal as a proxy for AC Y signal, then the fan operates longer than necessary, but this simple control method increases energy consumption by 20 to 50%
Solution Approach 1:
The patent implements feedback by having the fan controller continuously monitor the fan G signal from the thermostat and the building occupancy status. This feedback loop allows the controller to intelligently adjust fan operation, providing delays only when appropriate (occupied status) and eliminating them when unnecessary (unoccupied status), thereby reducing energy consumption without overcomplicating the control method.
Data Source
AI summary
Detecting a thermostat call for heating or cooling based on detecting a heat W or compressor Y signal is activated and energizing a fan signal output and operating a system fan/blower while the W or Y signal is activated and energizing the fan signal and operating the fan for a variable fan-off delay immediately after the W or Y signal is de-activated and de-energizing the fan signal and not operating the fan after the variable fan-off delay when a fan G signal is not activated. Detecting the fan G signal is activated and the W or Y signal is not activated indicating a fan-on duration control selected by a user, and energizing the fan signal and operating the fan while the fan G signal is activated and de-energizing the fan signal and not operating the fan and not providing the variable fan-off delay when the fan G signal is de-activated.