HVAC Fan Controller with Pressure Sensor Fault Diagnostics
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Solution Overview
Problem
Current HVAC systems face challenges in efficiently operating across a wide range of outdoor temperatures due to hardware interlocks that prevent direct control of condenser fans based on both refrigerant pressure and outside air temperature, leading to potential energy wastage and compressor damage from faulty pressure sensors.
Innovation Solution
An HVAC controller with separate data paths for refrigerant pressure sensors and condenser fans, allowing independent control and diagnostics, enabling operation irrespective of sensor states and generating error messages for faulty sensors, thus avoiding parallel sensor coupling and ensuring system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hardware interlocks are used to control condenser fans based on refrigerant pressure, then fan control is simplified, but system efficiency deteriorates and compressor damage risk increases due to inability to account for outside air temperature
Solution Approach 1:
The patent segments the control system into separate data paths: one for refrigerant pressure sensors and another for outside air temperature sensors. This allows independent evaluation of both parameters without hardware interlocking, enabling the controller to make optimized fan control decisions that account for both pressure and temperature conditions, thereby reducing energy wastage while maintaining control simplicity.
Solution Approach 2:
The patent adds the outside air temperature dimension to the existing refrigerant pressure control parameter. By incorporating temperature as an additional control dimension, the system can determine whether high pressure conditions require fan activation or if they are acceptable, preventing unnecessary fan operation and reducing energy consumption while protecting the compressor.
2Device complexity
If parallel sensor coupling is used, then hardware interlocking is achieved, but diagnostic capability deteriorates and faulty sensors cannot be identified
Solution Approach 1:
The patent implements separate data paths for each sensor, allowing the controller to independently evaluate signals from multiple refrigerant pressure sensors and outside air temperature sensors. This segmentation enables the system to identify which specific sensor is faulty by comparing readings across different paths, maintaining hardware interlocking benefits while restoring diagnostic capability.
Solution Approach 2:
The controller continuously monitors sensor inputs through separate data paths and provides feedback on sensor performance. When a sensor reading is inconsistent or out of range, the system can identify the faulty sensor through the isolated data path, enabling diagnostic feedback without requiring complex hardware interlocking changes.
3Device complexity
If condenser fan speed is controlled solely based on refrigerant pressure, then pressure management is simplified, but operating efficiency deteriorates under varying outdoor temperatures
Solution Approach 1:
The patent incorporates outside air temperature as an additional control dimension alongside refrigerant pressure. The controller evaluates both parameters to determine appropriate fan speed settings, allowing the system to operate efficiently across varying temperature conditions while maintaining simplified control logic through integrated software-based decision making.
Solution Approach 2:
The system dynamically adjusts condenser fan speed based on real-time conditions of both refrigerant pressure and outside air temperature. This dynamic control allows the fan to operate at optimal speeds for current environmental conditions, improving overall system efficiency while the integrated control approach keeps the control logic manageable.
Data Source
AI summary
An HVAC controller, a method of operating an HVAC controller and an HVAC system employing the controller or the method. In one embodiment, the HVAC controller includes: (1) a processor couplable to at least two refrigerant pressure sensors via separate data paths to receive input signals therefrom and further couplable to a compressor stage and a condenser fan to provide output signals thereto, and (2) memory coupled to the processor and storing a software program having program instructions capable of causing the processor to command the compressor stage or the condenser fan to turn on irrespective of a state of an input signal generated by either of the at least two refrigerant pressure sensors, and generate an error message at least partially depending upon whether or not a high pressure shutdown occurs after the processor commands the compressor stage or the fan to turn on.